Pottery Making illustrated 1

2

ClayLinksby Barbara Coultry....................................................................................tSee exotic sites, explore the unknown! Journey with our web captain to far-flung cultures and their pottery.

The Airbrushing of an Abstract Expressionby Douglas Kenney......................... ...........................................................SWalk through the step-by-step masking and airbrushing technique used to create a multilayered abstract expressionist piece, and see how, through simple steps, a complex and fully developed design emerges.

Firing with Paper Saggarsby Dannon Rhudy ....................................................................................1AGet all the benefits of saggar firing while protecting your kiln, saving space and hold­ing combustible materials right next to your work where they will do the most good.

Pouring to Perfection—Lips and Spoutsby Ivor Lewis............................................................................................ 18Form lips on jugs, ewers and pitchers and make functioning teapot spouts when you understand a few techniques and principles.

The World of Electric Kilns .............................................. 2AIn this special section, we’ve put together some basic information on topics that will help you to better understand how your kiln works, and how you can get the best results while using them.

The Degrees of Kiln Firing.......................................... 24Pyrometric Cones—Measuring Kiln Heatworkby Tim Frederick ............................................................................ 26How to Load a Kiln..................................................... 28Kiln Controllersby Mike Sievers .............................................................................. 30Elementary Kiln Repairby Michael Leonard........................................................................ 32Basics of Electric Kiln Heatingby Jeremy Willis.............................................................................. 34

Venting Electric Kilnsby Jeff Zamek ..................................................................................37

How to Throw a Potby George Juliano with Elizabeth Hudgins............................................. 41Discover this successful method for teaching someone to throw on the wheel.

Off the Shelfby Sumi von Dassow.................................................................................46Find out what kiln books would suit you best in your studio.

Building a Domed Cylinder Kiln—the Sequel...................47Katy McFadden, with the help of Don Adamaitis, goes from print to practice by con­ducting a 2-day raku-kilnbuilding workshop.Cover: “Mystery,” 27 inches in diameter, stoneware, by Douglas Kenney. See story p. 9.

Editor: Bill JonesProduction Manager: John Wilson Graphic Design: Debi Hampton Graphic Production: ErlaWise Advertising Manager: Steve Hecker Advertising Assistant: Debbie Plummer Customer Service: Mary Hopkins Publisher: Mark MecklenborgEditorial, Advertising & Circulation Offices

735 Ceramic Place PO Box 6136

Westerville, OH 43086-6136 Phone: (614) 794-5890 Fax: (614) 794-5892

E-mail: potterymaking@acers.org Web site: http://www.potterymaking.org

Pottery Making Illustrated (ISSN 1096-830X) is pub­lished 5 times a year by The American Ceramic Society, 735 Ceramic Place, Westerville, OH 43081. Standard mail (A) postage paid at Westerville, OH.Opinions expressed are those of the contributors and do not necessarily represent those of the editors or The American Ceramic Society.Subscription rates: One year $18, two years $34, three years $49. Add $15 per year for subscriptions outside North America. In Canada, add GST (R123994618). M payments must be in US$ and drawn on a US bank. Allow 6-8 weeks for delivery.

Advertising: Ad rates and ad information are avail­able on the web site or by contacting Steve Hecker

at the address above or by phone at (614) 794-5809.Change of address: Send your change of address via e-mail or to the Circulation Department. Allow six weeks advance notice.Contributors: Writing and photographic guide­lines are available on request and on the web site. Mail manuscripts and visual materials to the edito­rial offices with a self-addressed postcard for notifi­cation of receipt.Photocopies: Permission to photocopy for per­sonal or internal use beyond the limits of Sections 107 and 108 of the U.S. Copyright Law is granted by The American Ceramic Society, provided that the base fee of US$5 per copy, plus US$0.50 per page, is paid direcdy to the Copyright Clearance Center, 222 Rosewood Dr., Danvers, MA 01923 USA (508) 750-8400.This consent does not extend to other kinds of copying, such as copying for gen­eral distribution, for advertising or promotional pur­poses or for creating new collective works. Requests for special photocopying permission and reprint requests should be directed to the Director of Publications, The American Ceramic Society, PO. Box 6136, Westerville, OH 43086-6136.Back Issues: When available, back issues are $5 each plus $3 postage for the first copy and $1 for each additional copy thereafter. For orders outside North America, add $6 ($2 for additional copies). In Canada, add 7% GST.Postmaster: Send address changes to Pottery Making Illustrated, PO Box 6136, Westerville, OH 43086-6136.

Copyright © 2000 The American Ceramic Society All rights reserved

4

Other People, Places and TimesRaise a pot to your ear and listen as you would to a conch

shell. Do you hear people laughing on distant shores, pots clat­tering in a scullery, wine being poured for men in togas? If you’re an archaeologist or anthropologist, you’re probably sput­tering, “Of course, you ninny!”

So, lift that pot to your ear, travel through space and time, learn about clay artists both then and now, and do it all on the Internet while sitting warm and safe in a comfortable chair.

by Barbara Coultry

Oaxacan Pottery: Traditional Ware of Southern Mexicowww.foothill.net/~mindlingEric Mindling draws you in, making you dream of chucking it all and disappearing to a place where you can meander amongst potters who still form clay in the ancient ways. Designed by Eric’s talented father, Tony, this site takes you on a tour of seven villages in Mexico where Eric lives and works. You’ll learn about the potters, their way of life and their methods for fash­ioning their ware. You’ll be treated to pictures of pots that are beautiful in their simplicity. As a bonus, you’ll get to travel in Eric’s shoes, tasting the life of an American immersed in the subculture of another country.

Athenian Painted Potterywww.users.globalnet.co.uk/~loxias/vase_nnenu.htmAndrew Wilson is a classical scholar who, like so many people on the Net, joyfully and freely shares his knowledge. He’ll take you back to ancient Greece where you’ll follow long-ago pot­ters as they paint and fire a vase. From there, you’ll travel beyond the potter to “The Drinking Party” and then into “The Women’s Quarters.” Your high-school studies of Greek society probably never included these far more interesting aspects. Best of all is that you’ll view everything from an angle that’s near and dear to us: ceramics.

L’Asie Exotique www.lasieexotique.comMore than a mere photo gallery, L’Asie Exotique is a collection of Asian folk art augmented by articles explaining and dis­cussing what you see. You’ll be especially interested in clicking on Ceramics and on Netsuke but, since ceramics is not an iso­lated art, you might end up wanting to see all the art on this site. Be sure not to miss the informative articles on such sub­jects as “Maneki Neko, Feline Fact and Fiction” and “Devil Dance Masks of Sri Lanka.” You’ve never heard of “Maneki Neko”? All the more reason to visit L’Asie Exotique.

6

Andy Clift’s ClayStationwww.claystation.comYou may think I’ve strayed from this columns subject, but upon arriving at ClayStation, click on Ceramic Resources, then Guide to Ceramic History. ClayStation has far more in it than the subject of this column. Andy Clift has been designing (and constantly adding to) what is quickly developing into a hub for ceramics artists. It has a gallery, formulas, techniques, help for firing and equipment building, safety tips, paper clay, links, a buyer’s guide.... Well, you get the picture. Because it’s always changing, always being added to, this isn’t a site to visit, then forget about. Bookmark it.

Ceramic Collection and Archive, University of Wales, Aberystwythwww.aber.ac.uk/~ce rwwwClick on “Jamaica” for an interview-style look at this island’s pottery.Los Angeles County Museum of Art www.lacma.orgClick on “Permanent Collections” for a tour of art from various countries and eras. There’s enough ceramic work mixed in to please you.The Museums of the Potterieswww.stoke.gov.uk/museumsThis is a four-star site that takes you on a tour visually and historically of the Stoke-on-Trent potteries. Don’t miss a click here.Traditional Crafts of Japanwww.wnn.or.jp/wnn-craft/engSelect “Pottery” and “Porcelain,” but don’t hes­itate to inspect areas such as Paper, Lacquer and Bamboo.Asian Artswww.asianart.comThough a potpourri of media, you’ll also find ceramics at Asian Arts. Do look at “Images of Earth & Water ”Smithsonian National Museum of American Historywww.si.edu/organiza/museums/nmah/ve/vidal/index.htmTrue, this site has no ceramics, but the wooden sculptures and masks could just as well have been made of clay.Ethnographicawww.ethnographica.comThis is African art wrapped in a web site that’s not to be missed.9000 Years of Anatolian Womanwww.arzu.com/turknet/ninethousand/index.htmlThrough the arts, sculpture and vessel, walk through history with Anatolian women.African Pottery Forming & Firing Techniqueswww. u i owa. ed u/~ i ntl/l i n ks/rft/potte ry. ht m IWatch a slide show of how our fellow potters in Africa produce ware without any modern equipment.Experiments with Early Medieval Potterywww.physics.mq.edu.au/~gnott/Miklagard/ArticlesRunning from construction all the way to the final pit firing, this site describes an experiment in reproducing pottery using the methods of medieval Europe.Pottery Making illustrated 7

8

Spraying ceramic underglazes is one of the best and easiest ways to create hard-edged, geometric shapes and subtle shading on ceramic pieces.

My approach to ceramics is as a fine-art medium with abstract geometries juxtaposed against organic qualities of natural earth, where I try to create a harmony between nature and manmade sym­bols. Oriental painting and prints, combined with my experience, have had a profound influence on my work, but I’ve also been influenced by American abstract expressionist painters. Abstract painter Hans Hofman, who coined the phrase “Push and Pull,” uses geometric shapes on an organic background to create implied depth. And another source of inspiration is the work of Jackson Pollock, with his famous splash technique to create depth. Computers and cities also have a small voice in my cre­ations.

Above

The combined effect of abstract expression­ism and my glazing techniques is the devel­opment of my artistic vision. And, with each line and rectangular shape imposing a struc­ture onto the organic background field, a new relationship is formed within each piece.

“Lines and Land” 37½ inches in diameter, stoneware with airbrushed and brushed under­

glazes, overglaze and gold luster. Douglas Kenney’s plates are as large as 39 inches in diame­

ter, which would cover a normal dining table. The plates’ designs are a combination of mask and resist tech­

niques with colored ceramic underglazes airbrushed on top of a clay background.

Pottery Making ILLUSTRATED 9

PH

OTO

S: C

AR

L S

CA

YA

N, P

AU

L G

UB

A, D

OU

GLA

S K

EN

NE

Y

AIRBRUSHINGan ABSTRACT EXPRESS ION

by Douglas Kenney

Left

Kenney uses a Paasche Type H airbrush and #118 Critter sprayer powered by a Campbell Hausfeld Professional 6½ HP portable, 230-volt air compressor. Interchangeable plastic containers make for easy color change.

Large plates are hand-formed from a slab of clay embedded with dry colored clays. These organically decorated slabs are placed on huge 46-inch convex plaster molds, then he throws a set of three foot rings on the back of the plate for support during firing and presentation. The plates are bisque fired prior to glazing to provide a durable working surface.

The ProcessThe ceramic medium is complex

and relies on many techniques and processes that one masters over time. Airbrushing is one of those tech­niques, and I chose to use an air­brush in graduate school because of the crisp lines achieved with under- glazes and masking tape (used as a resist), and the ability to spray photo- silkscreen images onto my ceramic plates and sculptures. I’ve found spraying ceramic underglazes is one of the best and easiest ways to create hard-edged, geometric shapes and subtle shading on ceramic pieces.

For thousands of years, airbrush­ing on ceramics was done in China using spraying apparatuses usually powered by an artists lungs. With the invention of the air compressor, spraying glazes became more com­monplace, and is now widely used by ceramic manufacturers and stu­dio ceramists for efficient glaze application.

The spraying technique is employed on pots or large sculptures where dipping, pouring or brushing make it difficult to achieve even coatings. I’ve created an airbrush application technique that features layering with underglaze colors.

The piece shown in the follow­ing 12-step process is a 27-inch- diameter ceramic plate bisque-fired to 1800°F (982°C) to provide a durable porous surface. A dry- colored clay background was made on the plate while it was in the leather-hard stage. I used a combi­nation of commercially available and studio-mixed low-fire underglazes. For example, my rose/red under­glaze is a mix of Westerwald Chemicals Rose/Red #5690 stain and my low-fire underglaze base recipe.For Further Reading

Peter Fraser Beard,Resist and Masking

Techniques. Philadelphia,PA: University of

Pennsylvania Press, 1998.

UnderglazesUnderglazes are ideal for air-

brushed designs. Many low-fire underglazes are available com­mercially from manufacturers and suppliers.These airbrush wonder­fully onto bisqueware.

During the firing process, underglazes melt somewhat, fus­ing to the clay surface, but do not melt like glazes and form fuzzy lines. Underglazes stay where they are sprayed or resisted, mak­ing crisp shapes.

I make underglazes from the clay body I’m using and tint them with commercially-prepared ceramic stains (see recipes). I mix my own colors this way except when I work at earthenware temperatures.

A fired glaze provides a trans­parent, durable, protective coat­ing after glaze firing. To seal the underglaze, a clear glaze can be brushed, dipped, poured or sprayed over the entire surface of the work. I recommend spraying the clear glaze instead of pouring or brushing, because it may smear the underglaze decoration.

Kenney Low-fire Underglaze Base

Clay Body............................... 25%Feldspar..................................15Frit 3195.................................. 20Flint (Silica) ............................10Ceramic Stain......................... 30

100%Add: CMC............................... 2%

Bentonite ...................... 2%Kenney Mid-range Underglaze Base

Clay Body............................... 30%Feldspar..................................20Frit 3195.................................. 10Kaolin (EPK)........................... 10Ceramic Stain......................... 30

100%Add: CMC............................... 2%

Bentonite ...................... 2%Mix ingredients with water and screen to 80 mesh before airbrushing.

If you use Westerwald #5510 Rose stain, replace clay body with Cornwall stone.

WARNING: Free silica in the underglazes and clear glazes poses a health threat and is harmful to breathe. Airbrushing must be done in a spray booth equipped with a filter and vented to the outside. In addition, a NIOSH-approved respirator must be worn.

10

Tools and Materials• Masking tape (different widths)• Masking-tape rolls as a resist for circles• Round, plastic container lids for silhouettes• Green plastic drafting templates• Adhesive mailing labels and pricing stickers• Cut-out shapes from Mylar, bristol board

or manila folders• Geometric-shaped wooden blocks

• Metal lath and various metal screens• Silkscreen images—largest mesh screen

to allow underglaze through• Sprayers: Check with your local

ceramics-supply source• Respirator• Spray booth• Air compressor (check specifications

based on type of airbrush you use)

Step 1: An ordinary graphite pencil was used to mark a grid on a bisqued plate. The grid helps in aligning templates and masks, and the pencil marks burn out during firing.

Step 2: Next, various widths of masking tape (e.g., ¾”, 1", and 3" widths) were applied in a geometric pattern.

Step 3: The small grid pattern on the left was sprayed with rose/red underglaze, then a mixture of rose/red and Duncan Stardust Blue underglaze (about 50:50) was sprayed over the masked-off areas on the right side.

Step 4: Duncan Harvest Gold under­glaze was brushed on the red squares on the lower left, and all the tape removed to reveal the first layer of information, then two more areas were masked off.

Step 7: On this layer, Laguna Rosebud #8058 underglaze was used on the lower left, Duncan Canary Yellow above, and Duncan Indian Red on the right.

Pottery Making ILLUSTRATED

Step 5: Next, the upper right shape was sprayed with Duncan #146 Purple under­glaze, and Laguna #EM-8034 Red underglaze was sprayed on the bottom.

Step 8: To splash colors onto the Duncan Indian Red portion, the unaffect­ed areas were protected with newspaper. Then, using a brush, Duncan Harvest Gold, Studio Rose/Red, Duncan Morocco Red, Duncan Bright Green and Duncan Stardust Blue were splashed on.

Step 6: Again, the tape was removed, then three new areas were masked off for the next layer.

Step 9: After the newspaper and tape were removed and the design assessed, the last three areas were masked off.

11

Step 10: Light coats of Duncan Deep Purple underglaze were sprayed on both sides and Laguna Lapis Blue underglaze at the bottom.

Step 11: The tape was removed, then a line of Duncan Bright Green underglaze was added at the top in a diagonal stripe.

Step 12: Finally, the remnants of tape were removed and the entire surface (front and back) sprayed with Laguna Clear Glaze #EM 2002; the foot of the plate was sponged to remove excess glaze before firing. This plate was fired to Cone 05 in an electric kiln.

This is the finished plate. A crimped aircraft cable with a loop around the backside of the foot makes an efficient way to display the plate on a wall. This plate, titled “Mystery,” was completed in 1997 and measures 27 inches in diameter.

Detail of completed plate.

12

Another way to build up a background is to place pieces of paper overlapping on a plate’s surface, and spray the angle. Move the sheets again in another configuration and spray again. Repeat this many times with different colors to achieve a patterned back­ground.

One of the main reasons Kenney chose to use an airbrush in graduate school was because of the crisp lines achieved with underglazes and masking tape, and the ability to spray photo- silkscreen images onto ceramic plates and sculptures. He found “spraying ceramic under­glazes is one of the best and easiest ways to create hard-edged, geometric shapes and subtle shading on ceramic pieces.”

“Architectural Rain,” 26 inches in height, press- molded stoneware with airbrushed and brushed underglazes, overglaze and gold luster. Airbrushing underglazes in combination with other processes, such as brushing, carving, glazing and sandblasting, enhances both real and implied visual depth.

Doug Kenney started working with clay when he was a senior in high school. He went on to receive degrees from San Diego Mesa College (AA), San Diego State University (BA) and Rochester Institute of Technology's School for American Crafts (MFA). He taught ceramic art at San Antonio College in Texas; worked as an artist-in-residence at the Shigaraki Ceramic Cultural Park in fapan; and now lives in Hawaii, where he has a studio. Recent ceramic exhibitions have been held in Paris, Tokyo, and Seoul, Korea.

Pottery Making illustrated 13

Firing with Paper Saggarsby Dannon Rhudy

A clay container to protect wares from the direct flame of the kiln. The word is derived from a contracted form of the English “safe guard.”

Low-fire salt firing and pit firing can create beautiful surface effects on burnished wares. The best way to achieve these effects consistently seems to be with the use of saggars, which keep the combustible mate­rials close to the surface of the work. In that way, the volatizing salts and other combustibles impinge more directly on the clay, creating the soft blacks and colors that make these wares so appealing.

The ProblemYou can build a brick saggar

inside a gas or raku kiln, but often the saggar itself takes up so much room that little space remains to accommodate your work. And when building a large brick saggar inside a reduction kiln, it can be difficult to reach the rear wall of the saggar to seal it properly.

When firing large or odd-shaped pieces, you can construct a brick “pit” and fire with the usual wood, sawdust and/or dung. There are drawbacks to such firing methods, however, since lots of fuel is required, and heating is uneven and may not reach sufficient tempera­ture to achieve the desired results. But the greatest difficulty may be that such open fires create a lot of smoke, which in urban settings or on many campuses may not be feasible.

A SolutionMy own saggar-fired pieces are

generally large, and I have adopted the use of paper saggars to fire these pieces. The advantages of using paper saggars are:• Easy (if messy) to make.• Saggar only needs to be slightly

larger than the work itself.• Molds itself to the shape of the

piece.• Holds the combustible materials

right against the work, where they do the most good.

• Can be fired in an ordinary gas kiln to any temperature desired, without combustible materials escaping to damage the kiln. Prepare your work for firing in

your usual way. I either burnish mine or use terra sigillata and polish with a cloth. I bisque fire to Cone 010, but you can bisque either higher or lower, depending upon the degree of sheen you want to maintain. Pieces fired in paper saggars must be bisqued first, for reasons that will become apparent.

WARNING: The saggar tech­nique described here is not suit­

able for electric kilns.Dannon Rhudy did undergraduate work at Texas A&M University/Corpus Christi and graduate work at the University of North Texas School of Visual Arts. She currently maintains a studio and teaches ceramics and drawing at Paris Junior College in Paris, Texas. You can e-mail comments to her at potter@koyote.com

Figure 1

Prepare a bucket of slip using any clay— ball clay, kaolin, scrap clay, etc. Make sure the slip is relatively smooth and free of lumps and about the consistency of a thick latex paint.

Figure 2

Put some combustible materials (e.g., sawdust, wood chips) in a paper bag, place a bisqued pot on the materials, then cover the pot completely with what­ever combustibles you choose.

“Between Me and the Sunset,” 26 inches in height, wood-fired to Cone 8 in a paper saggar with salt, copper sulphate, steel wool and wood chips.

14

Making the SaggarStep 1. Prepare a bucket of slip

using any clay (ball and/or kaolin work well), or use recycled clay from your slip barrel. The slip should be relatively smooth, free of lumps and about the consistency of thick latex paint (see figure 1). If the slip is too thin, the saggar tends to crumble when it’s fired.

Step 2. Gather a generous supply of newspaper. If the piece(s) to be fired are relatively small, get some large (grocery size) kraft paper bags. If the work is too large to fit into an available bag, construct a container by taping sheets of newspaper together large enough to contain your piece and the com­bustible materials. DO NOT use plastic bags or plastic tape.

Step 3. Place part of your com­bustible materials in the newspaper container or the bag; put the work in (see figure 2). Cover completely with whatever combustibles you choose to use to achieve color. I use combinations of sawdust mixed with a little salt and Epsom salts, maybe a piece or two of charcoal, various grasses, seaweed when avail­able, dried manure, sometimes salt- soaked string wrapped around the piece, extra-fine steel wool—-just about anything that burns can be used for interesting effects. I occa­sionally use copper sulfate (dis­solved in water and brushed on the pot) to achieve reds. When black pots are desired, I fire with a lot of sawdust to a lower temperature (perhaps Cone 018).

Figure 3

After the package has been taped shut, begin covering with slip-coated paper (a technique similar to papier mache). Continue to add slip-coated paper until there are no bare or thin places remain­ing. This part of the process is quite messy.

Step 4. Close the bag or news­paper container. Fasten with paper tape to hold the package together. This “package” holds the com­bustibles against the work, and keeps wet slip from adhering to the piece.

Step 5. Now you are ready to build the saggar. Working quickly, take a sheet of newspaper, dip it quickly into the slip and apply it to the package (see figure 3). Alternately dipping and wrapping, completely enclose the piece in slip-covered newspaper. When the first layer is complete, add several more layers of slip-covered paper. Be sure that there are no bare or thin places—you need several layers all the way around, including underneath, to make a strong enough saggar. Add a little extra slip over the whole thing to complete the saggar.

Step 6. When you’re finished making the saggar, place several lay­ers of dry newspaper on the kiln shelf where the saggar(s) will go. This prevents the wet slip from sticking to the shelf. Place the still- wet saggar on the paper-covered shelf. It must be placed on the shelf while wet so that the thin clay shell does not crack. Put cone packs in the kiln where the peeps are. I usu­ally fire these to Cone 010—it will be slightly cooler inside the saggars. If doing numerous pieces in a large kiln, light the kiln immediately and keep it on a very low flame for 2 or 3 hours (or candle overnight). Gradually increase the heat until

Figure 4

Here is an example of a paper saggar bundle after firing.

the desired temperature is reached. The longer the firing time, the closer the temperature inside the saggar(s) will be to the ambient temperature in the kiln.

Tip: When firing a single piece, I fire it in a raku kiln. I place the piece in the kiln and light it at once, while the slip is still wet. I fire slow­ly, at first, just as in the larger kiln. Once the firing cone is down, I leave the kiln on (soak) for another hour or so, to be sure the tempera­ture inside the saggar has had time to catch up to the outer tempera­ture. Such a raku-kiln firing gener­ally takes 3-4 hours for a large (20- inch-diameter) piece.

Step 7. After firing, I allow the work to cool for several hours or overnight, because it is easier to unload when cooler (see figure 4). The saggar shell will be fragile (see figure 5)—the clay layers are thin­ner than eggshells. When removing paper saggars from the kiln, they sometimes crumble or break, scat­tering bits of fired clay onto the kiln shelves or floor, but the mess is easily removed with a whisk broom or shop vacuum.

The value of paper-saggar firing is that the kiln is protected from the residues of the firing, results are more consistent, temperature is consistent and easier to attain, and the size and shape of the work to be fired is of little consequence. Further, in classroom situations, an interested student can fire a piece or two in the raku kiln without having to wait for a class “pit-fire” project.

Figure 5

Paper saggars are very fragile and sometimes crumble and break after the firing when removing them from the kiln. Breaking open a saggar often reveals pleasant surprises.

Pottery Making illustrated 15

A specific selection of completed artworks by Dannon Rhudy and her students using the technique of “Firing with Paper Saggars.”

Student work, pierced form, 6½ inches in diameter, porcelain. Fired with Epsom salts, salt, sawdust, dried

manure, to Cone 010.Student work, open form, 11 inches in diameter, fired with sawdust and char­coal to Cone 018.

Round form, 10 inches in diameter, stoneware. Fired with salt, bird seed, seaweed, sawdust, dried manure, to Cone 010.

Large vessel form, 18 inches in diameter, porcelain. Fired with salt, Epsom salts, copper sulfate, steel wool, to Cone 010.Vase form, 9 inches in diameter, porcelain. Fired with salt,

Epsom salts, copper sulfate, sawdust, to Cone 010.

16

Pottery Making illustrated 17

by Ivor Lewis Forming Lips on Jugs, Ewers and Pitchers

After you understand the principle of what makes a lip dribble and drip (see Touring to Perfection—Fundamental Principles,” PM I Fall 1999), the next step is to put theory into practice. Here’s how to make efficient pouring edges for a variety of forms.

brow and shape your form (jug, ewer or pitcher). This may be based on a historic example, have a unique style, or be made to conform to a pattern common for a range of kitchen utensils you have designed. In each of my diagrams, the actual profile of the lip has been exaggerated to emphasize the change of form that occurs when pressure is applied between finger and thumb. In addition, the proportions illustrated are sug­gestions rather than prescriptions.This is only one solu­tion that can be used to solve the problem of making a rim that pours without dribbles or drips.Step 1 - Form a Collar

After you’ve formed the basic shape of the piece, form a collar on the rim by leaving a thick bead of clay, which will provide clay that can be drawn up and modeled to make a well-proportioned lip. The collar should be at least twice as thick as the wall of the neck. Try to give the collar a circular cross-section with only a small fillet where it flares into the neck. As your skill develops, you may wish to embellish the outer contour of this collar with your fingers or a profile rib.Step 2 - Pull the Collar

Starting on the far side of the piece, place your mid­dle finger outside the pot and your thumb inside, then lightly grip the neck below the collar with your other hand. Squeeze slightly and start gently pulling the clay up. Move to the left and right, and pull the bead up an equal amount. Maintain a thickness equal to that of the wall of the pot at this stage. Thin about a quarter of the circumference of the collar. Use slip rather than water as a lubricant on your finger and thumb as you pull.Step 3 - Extend and Thin the Tongue

Continue thinning the clay into a low, wide, thick tongue, always starting at the center and pulling upward and squeezing, then repeating the motion to either side. Continue the process, but progressively limit movement to the sides until only the center portion is being thinned. The result should look like a long tapered fingernail and the extreme edge should be less than half the original thickness of the neck. This

tongue of clay should taper smoothly back into the throat of the jug.Step 4 - Roll and Stretch the Tongue Outward

Rotate the wheel so the tongue is close to you. The lip is going to be bent out and over. Wet your middle fmger with slip, and place it against the clay on the inside of the part you have just worked. Gently sweep your fmger from side to side. Start in the center and as you sweep, also gently pull against the clay, bringing the lip toward you to thin and bend the lip over. This stretches the clay, so you may need to support the clay with your other hand on the outside. Work toward get­ting a smooth flowing curve that continues the line of the neck outward without interruption. Repeat the modeling action until you’re satisfied with the shape. Try to keep the contour of the symmetrical and even in thickness.Step 5 - Complete the Gully

Since a wide gape would be prone to splash and spill liquid rather than pour it in a well-directed stream, you’ll need to narrow the gully by sweeping fmger and thumb up the outside of the throat of the pot. While doing this, place the fingers of your other hand inside to preserve the contour and prevent the gully from narrowing too far. This gives the channel high shoulders that will constrict and narrow the stream of liquid as it flows over the lip.

When finished with this process, you should have produced a gully that will deliver a well-controlled steady stream of liquid. Its thickness should be uniformly tapered from the neck to its top edge at the lip. Make sure that the lip edge is thin but does not droop downward. The gully should always slope back (see correct image) from the lip into the cavity of the vessel. Allowing the front edge of the lip to droop (see incorrect image) increases the chance that liquid will drip or dribble. A sharp lip that instantly cuts the flow and a gully that makes liquid run back down into the body of the pot are essential if dripping or dribbling are to be avoided when the pot is used.

18

T

Points to Remember• If any shaping tasks are done too

vigorously, the lip may split, sag or become distorted.

• Problems may occur if the origi­nal collar was not stout enough to provide sufficient clay for the process. Pulling a spout is a deli­cate task, and must be done when the clay is at its most frag­ile state. Several attempts may be needed before you attain the finesse that combines swift steady movements with a sensitive soft touch.

• Illustrations here have been exaggerated to emphasize princi­ples. In your work, the lip does not need to project so far for­ward, the gully does not need to be as prominent, nor the side shoulders so high.

• Do not try to create a lip with a knife edge during the early forming stages. The lip is very fragile and needs to set up and become leather hard before it can be wiped and smoothed with a fine sponge.

• It is essential to have a sharp lip that does not droop and shoul­ders that restrict the breadth of the stream of liquid.

• When glaze is applied, it may form a bead on or under the lip. This should be smoothed out, but be careful not to entirely remove the glaze.

• Lip and spout design is influ­enced by the vessel contour and the design relationships between foot, belly, neck and rim. The ini­tial thick collar may be given a complex profile that you can incorporate as a design feature, adding visual and tactile empha­sis as it draws attention to the spout or lip.

Step 1 - Form a Collar

Step 2 - Pull the Collar

Step 4 - Roll and Stretch the Tongue Outward

Step 5 - Complete the Gully

the TongueStep 3 - Extend and Thin

Pottery Making illustrated 19

by Ivor Lewis Forming Spouts on Teapots

Ceramics studio practice provides fertile ground for invention and elaboration of teapot design. Yet, whatever form a teapot takes, if it’s to function with a degree of efficiency as a utensil, it must dispense tea without trauma or despair—no dribbles or drips.

It is not enough to simply trim the end of a teapot spout to a sharp beak because this termination will not achieve a sharp cut-ofF. A channel must be engineered to give a smooth uninterrupted passage for the flow, and any change in direction will cause an eddy and the potential for a dribble. While there are many solutions to forming a dripless teapot spout, here’s one easy solution that pro­vides a razor edge and smooth passage.

Note: As with the pitcher and jug lip, the slope of the spout should be back down into the pot. The tip of the spout, if bent forward and down, will always tend to drip. The problem of drips and dribbles has a single solution regardless of whether the spout is cut across or left untrimmed.

The Ideal ToolThe ideal tool for shaving and

scraping the inside of the spout is a _ground piece of hacksaw blade. If this blade is insert­ed well into the cavity and laid flat against the clay, it can be pulled out with a twisting, sliding action that shaves clay from the lower side of the bore of the spout. By cutting first from one side and then the other, it is possible to make a smooth curved plane from deep within the spout to the sharp beak. Do this slowly, first on one side and then on the other. The hole will change in cross-section from a circle to an oval. This new channel can be further refined by wiping gently with a soft damp sponge. Do not increase the width of the hole nor take material from the top side of the spout.

Trimmed SpoutIf you intend to trim the length of the spout, make

an almost horizontal slice across the end of the tube (B). Next, shave the lower rim (C) inside the tube to form an oval opening (D).Trimmed Spout

If you choose not to trim the spout, you only need to remove material from the lower side (E).This elim­inates the angular change that separates the inside of the tube from the flat face that has been cut to give a pointed end to your teapot spout. Take care not to shave so far that the front edge of the sharp beak is sliced away. This method should be equally effective in preventing drips and dribbles.

Where the design of the teapot has a drooped spout (F), make sure that the curve forward and down is not excessive so that when the pot is brought upright after pouring is complete, remaining tea will flow back into the pot.

Rotating Teapot SpoutsEvery clay has the ability to alter shape during

firing, depending to some extent on the technique of the potter, the nature of clay and the firing schedule. This characteristic is most notable with teapot spouts, which will twist counter to the direction of throwing used dur­ing the forming process. An accurate picture of the degree of rotation for a particular clay can be ascer­tained by testing one teapot. Slice the spout precisely horizontal and fire the pot. Note the degree of rotation and its direction. Apply this measure in the opposite sense when trimming future spouts of this design.

Ivor Lewis is a retired teacher of Arts, Crafts and Sciences. He has a studio at his home in Redhill, South Australia, and is a frequent contributor to Pottery Making Illustrated, as well as several other ceramics magazines. He continues making, glazing and decorating pots. Contact Mr. Lewis via e- mail at ivorredhill@.yahoo.com.au or by snail mail at Box 10, CMA Redhill, South Australia 5521.

20

Pottery Making illustrated 23

Th e Wo r l d o f El e c t r i c K i l n s

The Degrees of KfLN FiringFiring converts ceramic work from weak greenware into a strong, durable form. As the temperature in a kiln rises, many changes take place in the clay; and, if all goes well, you end up with a permanent result ready for using, showing or giving. Understanding what happens during the firing can help you avoid problems that may ruin hours of effort on your part. The following chart provides highlights of what happens wnen firing your work.

24

Th e Wo r l d o f El e c t r i c K i l n s

Pyrometric Cones - Measuring K LN Heatwork

Pyrometric cones are used inside a kiln to measure “heatwork.” Heatwork is a function of both time and temperature, and measur­ing heatwork is important because both time and temperature are required to vitrify clays and glazes.

Pyrometric cones are made from ceramic materials. When a cone is heated during firing, portions of it begin to melt, and as further melt­ing occurs, or as time passes, the cone bends under its own weight. The bending of the cone is observed to determine the heat­work the ceramic ware is receiving.

The rate at which the heat is increased in the kiln, particularly during the last 90 to 120 minutes of your firing, has a major effect on when a cone will bend and at what temperature. Normally, the faster the heating rate, the higher the temperature will have to be to bend the cone. For example, if you fire a kiln at 270°F per hour, you’ll reach Cone 4 (2158°F), but if you heat at a rate of only 108°F per hour, to achieve Cone 4, you will only have reached 2120°F. It’s also possible to get cones to bend by soaking (hold­ing) the kiln temperature near the end point of the cone. Prolonged soaking can even cause several con­secutive cone numbers to bend; for example, you could get Cones 07, 06 and 05 to bend at the same tem­perature if you held that tempera­ture long enough.

It is important to note that cones DO NOT tell the temperature of a kiln. Cones indicate the amount of heatwork being done on your pots, which is critical to the quality of your firing.

Figure 1

Figure 3

Figure 5

Tim Frederick has been a professional studio potter for over 30 years, making production stoneware and one-of-a-kind pieces. He also works as a sales and marketing specialist for the Edward Orton fr. Ceramic Foundation in Westerville, Ohio.

26

Figure 1There are four types of pyrometric cones— bars (1 inch long), small cones (1½ inches high), large cones (2½ inches high) and self-supporting cones (2½ inches high).Figure 2The bar cones and small cones are used in a Kiln-Sitter®, an automatic shut-off device. A sensing rod rests on a cone, and as the kiln reaches temperature, the cone melts, the sensing rod goes down and a switch is tripped, thereby shutting off the kiln.Figure 3To achieve the best results, the Kiln-Sitter® sensing rod must be properly adjusted. The final shape of the cone indicates how well the Kiln-Sitter® is adjusted. Check the manual for instructions on how to adjust the device.Figure 4When using cones, it’s very important to have the mounting height and the proper angle with the bending face of the cone in the proper position. (Self-supporting cones do not require any adjustment or orienta­tion.) The base of the cone is angled 8°, which is the correct angle for the tilt. Typically, it takes 15 to 25 minutes for a cone to bend once it starts, depending on the cone number. The cone bends slowly at first, but once it reaches the halfway point (3 o’clock), it bends quickly. When the cone tip reaches a point level with the base, it is considered properly fired. This is the point for which equivalent tempera­tures are determined. Differences between a cone touching the shelf and a cone at the 4 o’clock position are small, usually a few degrees.Note: If a cone is soaked at a temperature near its equivalent temperature, it will con­tinue to mature, form glass and bend. The time for the cone to bend depends on sev­eral factors, but as a general rule, a 1 - to 2- hour soak will be sufficient to deform the next higher cone. A soak of 4 to 6 hours will be required to bend two higher (hotter) cones.Figure 5Using three cones during a firing is a com­mon practice. The 3-cone system consists of a cone that is one number cooler than the cone you’re firing to (guide cone), the cone you’re firing to (firing cone), and one cone number higher than the one you’re fir­ing to (guard cone). For a 2-cone system, use the guide and firing cones. Single-firing cones may be placed throughout the kiln as “witness” cones to identify the amount of heatwork throughout the kiln.

Figure 2

Figure 4

by Tim Frederich

Temperature Equivalents (°F)for Orton Pyrometric Cones

These tables provide a guide for the selection of cones. Actual bending temperature depends on firing conditions.

Once the appropriate bending cones are selected, excellent, reproducible results can be expected.

COURTESY OF THE ORTON CERAMIC FOUNDATION

Pottery Making illustrated 27

Th e Wo r l d o f El e c t r i c K i l n s

Loading an electric studio kiln is a fairly simple task, but there are basic procedures that must be followed to help ensure success. The following sequence illustrates some of the more common aspects of loading a kiln for bisque and glaze firings.

An assortment of kiln furniture is needed to hold and support ware during a firing. Furniture consists of shelves, posts, stilts, spurs, etc., made from refractory (nonmelting) materials capa­ble of withstanding repeated heating and cooling to high tem­peratures. To get started, you should have whole and half shelves, posts of various heights (3 to 9 inches), and stilts to give you the flexibility you need to make the most efficient use of kiln space. Tile setters (far right) are an example of special­ty furniture, and they come in a variety of configurations.Tip: Broken pieces of shelves may be used to add a little height to a post when needed.

Prior to loading, brush the top of the kiln shelves with a thin coat of kiln wash. If any kiln wash is flaking, use a wire brush or scraper to remove any loose material, then reapply a thin coat of wash. Kiln wash is not necessary for bisque firings because no glazes are used.

Place the first shelf on three 1-inch-high posts. Providing space below the first shelf is required if the kiln has a downdraft vent­ing system, but even if you don’t vent through the bottom, rais­ing the shelf is a good practice because it helps even the heat­ing of the kiln. Place props on subsequent shelves over the post below it. Using split shelves at various levels promotes cir­culation and more even heating of the ware.WARNING: Never stagger shelf supports, because the weight of the furniture and ware may cause the shelves to warp or collapse at high temperatures.

When loading greenware for a bisque fire, pieces may touch one another and can be stacked inside other pieces. Take care to have foot rims coincide for support and avoid stacking heavy pieces on fragile ones. Lids or covers should be fired in place, though tall knobbed lids may be inverted to save space.In a glaze kiln, glaze must be removed at least ½ inch up from the foot or base of ware (dry footed) to prevent it from sticking to the shelf when the glaze melts and runs. If the base or foot is glazed, prop the piece on a spur or stilt. As a general rule, always allow at least a ½-inch gap between pieces.

28

In a bisque or glaze kiln, position ware no closer than 1 inch from any heating element. This reduces the risk of any clay or glaze coming in contact with the element and also prevents the ware from heating too unevenly from one side to the other.

To avoid any interference in the functioning of sensing or shut- off devices, shelves and ware should always be placed at least 1 inch above or below any thermocouple or Kiln-Sitter® tube/sensing rod.

Place cones even with the center peephole. Assure that there is room around the cones to allow them to bend without any obstruction. Since peepholes are small on most studio electric kilns, use only a guide and firing cone.Note: To promote uniform heating and cooling, distribute work evenly, avoid tight spots, never fire a half load, stagger split shelves if possible, and avoid placing low shelves at the top or bottom of the kiln.

Pottery Making ILLUSTRATED 29

Th e Wo r l d o f El e c t r i c K i l n s

Like everything in this golden age of technology, the means of controlling the temperature inside a kiln has advanced rapidly. We’ve moved from an “intuitive sense” developed through years of trial and error, to visual inspection of pyro- metric cones, to mechanical shut- off devices, and now have electron­ic devices that can do everything but throw the pots for you.

Even though electronic con­trollers have been around for quite a while, they have only recently come down in price enough to fit into the average potter’s budget. What may have cost thousands of dollars 10 or 15 years ago is now only a few hundred. Because of this drop in price, electronic kiln con­trollers are no longer reserved for the industrial ceramic engineer. They are used by teachers, home hobbyists and professional artists all over the world.

There are many different types of kiln controllers. Some can control the atmosphere of the kiln as well as the temperature. The following is a look at the more basic units sold with most top-loading electric kilns and some front loaders.How a Controller Works

An easy way to understand how a controller works is to break it down to its core functions: sense, decide and act. A thermocouple senses the temperature in the kiln chamber and sends that information to the controller. The controller takes the information and compares it to the firing program input by the operator and makes a decision to act or not to act. If the program data indicate a need to act, the controller sends a signal for the relays to open or close. The relays are the compo­nents that control the power to the heating elements. When they are open, the power is off; and when they are closed, the power is on.

by Mike SieversProgramming

There are two types of programs that can be entered into the con­troller—custom-designed programs and programs that come with the controller. Programs that come with a controller are typically designed to simulate a firing using cones, hence they are commonly called “cone fire” programs.Custom-Designed Programs

Custom-designed programs are often referred to as “ramp and hold” or “ramp and soak” programs. They all are composed of one or more segments. A segment consists of three pieces of data: heating/cooling rate, ending tem­perature, and hold time. Below is a five-segment Cone 10 program designed for sculptural pieces with thick walls (see chart below).

Note that the first segment instructs the kiln to heat up at a rate of 50°F/hour until it reaches 150°F and then hold that temperature for six hours (to allow complete drying of the thick pieces). Segment 2 takes the kiln fairly slow through the removal of chemical water and organic materials, then segment 3 slowly moves through quartz inver­sion. Once the quartz inversion is passed, there is a rapid rise to 2100°F then a leveling off to 108°F per hour during the final stages of the firing. This is an excellent

example of how you can customize programs to meet specific needs. Most boards allow eight segments to use in constructing a program and six spots to save favorite pro­grams in permanent memory.

Ramp-and-hold programs do not calculate the heatwork for you, therefore it takes a good under­standing of heatwork to design your own program. Heatwork is a meas­urement that incorporates time and temperature. If you increase the time of the firing or the final temperature, you will increase the heatwork.

If you look at an Orton Cone Chart, you’ll notice that each cone value has a temperature associated with it. This temperature is only valid if the kiln is being fired at a specific rate during the last 150°F of the firing. Most controllers are calibrated using the 108°F/hour large self-supporting cone chart published by Orton. Therefore if you are firing slower than 108°F/hour, you’ll need to adjust the temperature down; determining how much will take a little trial and error.

Note: Just because you program the kiln to do something, it doesn’t mean the kiln is capable of achiev­ing it. For example, if you program a kiln for a rate faster than it can achieve, it will do only what it can.

Five-Segment Cone 10 Program (designed for sculptural pieces with thick walls).

30

Th e Wo r l d o f El e c t r i c K i l n s

Cone Fire ProgramsCone fire programs are popular

because the programs are preloaded into the software of the control board and the user only needs to load the right one. As mentioned before, cone fire programs are designed to simulate the heatwork needed to bend a pyrometric cone. The controller will automatically adjust the final temperature, depending on the speed at which the kiln is firing.

With the cone fire mode, you simply enter the cone you want to simulate, enter the speed you wish to fire, and how much time you would like to hold the temperature at the end of the firing. It is very common to enter a 5- or 10- minute hold at the end of the firing to allow the kiln time to balance out in temperature and give glazes time to flow.

Prior to controllers, it was neces­sary to regulate the heating rate of the kiln by coming back every so often to advance the switches. With the cone fire programs in the new controllers, the kiln automatically slows the rate down through critical temperatures.

Using a ControllerFor the most part, controllers are

relatively easy to use and accurate. Most problems associated with con­trollers can be prevented if the fol­lowing things are kept in mind:• Thermocouples are like heating

elements—they wear relative to use and must be changed occa­sionally. There are many different types of thermocouples but the most commonly used is the Type K. When Type K thermocouples wear, they begin to err toward an overfire. This is a gradual process and should be easy to catch by using pyrometric cone pads every so often.

• Relays need to be replaced on occasion. When one fails, it is often a good time to change all of them.

• Electronic components are sensi­tive to excessive heat and mois­ture. When controllers were first introduced to the studio market, they had a few problems that were mostly associated with heat. Since then, manufacturers have been able to design ways of insulating the circuitboard from the heat of the kiln. The problems occur when kilns are placed in tight confines with little circula­tion. The heat gets trapped in the room and the temperature rises.

By following the manufacturers installation recommendations, you should not have a problem with heat.

• Do not try to program the kiln beyond its capabilities. All kilns are rated to a set temperature. If the elements are in good shape and the power is sufficient, the kiln should achieve the rated tempera­ture in a reasonable amount of time. When elements begin to wear or there is a voltage supply problem, the kiln will take longer and longer to fire. The controller will eventually shut off the kiln in order to prevent an overfire caused by too much heatwork. This nor­mally occurs when the kiln is not capable of climbing at a rate of at least 12°F/hour.Kiln controllers have come a long

way over the last 15 years. They are more accurate and dependable than ever before. Automatic kilns have opened up a whole new world of freedom to artists—freedom to experiment with products that are difficult to fire, such as crystal glazes and glass, and freedom from having to babysit each firing. And every year, new features are being developed that can help potters solve firing problems.Mike Sievers is Marketing Director of Skutt Ceramic Products, Inc. For questions and com­ments, he can be reached at msievers@skutt.com.

Pottery Making illustrated 31

Th e Wo r l d o f El e c t r i c K i l n s

So, it’s Thursday afternoon and you’re about to try to squeeze in one last glaze load before heading to that craft show this weekend. You start loading the kiln, but darn it, you bumped and broke the thermocouple with a kiln shelf. No problem— you’re a potter, and that means you’re also a problem solver. Fixing an elec­tric kiln problem is not difficult. And if you have the right tools and a basic stock of parts on hand (see figures 1 and 2), keeping your kiln working at all times is relatively simple.The Basics

The act of removing and replacing a component is as easy as it sounds— if you can hold a screwdriver and a pair of pliers, you can do the rest. Simply figure out how the part was secured, undo it, move the wires from the old component to the new one, secure the new part and you’re back in business. Replacing kiln parts is a simple task, and a safe one, if you remember four important rules:1. Turn off the power supply.2. Test to ensure that you indeed

turned off the correct breaker.3. Mark the positions of any wires

you remove (hence the masking tape).

4. Make sure that all connections are as tight as possible.

Simple Problems,Simple SolutionsThe most important part of kiln

repair is understanding the prob­lem—there’s no sense in replacing a switch to remedy a broken element. I’ve selected a few of the most com­mon kiln problems and the steps needed to solve them.Problem: Kiln not reaching temper­ature.Solution: Test all the elements by placing a small piece of paper in each one (see figure 3), then turn the kiln on to its highest setting and make

Michael Leonard is the General Manager at Tucker’s Pottery Supplies, Inc. in Richmond Hill, Ontario.

by Michael Leonardnote of which elements make the paper smoke and which ones do not. If all the elements seem to work, then there are two possibilities:1. If the kiln has been gradually get­

ting slower and slower, it’s possible that it’s simply time to replace all the elements. Elements wear with time, and even though they may all seem to light up, they may just have worn thin enough that they can no longer put out the amount of heat your kiln requires to reach temperature. Replace the entire set of elements.

2. If the kiln or the elements are new, the problem could be related to the power supply. You may have purchased a kiln or elements that are not designed for the voltage in your studio, or perhaps you expe­rienced low voltage during just that particular firing. The electric company only has so much power available for your community, and if you were trying to fire at a time when all your neighbors were both cooking and using their air conditioners, it’s possible there wasn’t enough voltage available to get the kiln to reach temperature properly. If it’s possible that you bought the wrong kiln, call your supplier. If you were trying to fire at a time of peak demand, try again at a different time of day.

If one or more of the elements do not burn the paper then a little more analysis is needed.1. If your kiln uses manual controls

(i.e., switches and a Kiln-Sitter®), then determine how many ele­ments are controlled by each switch. If each switch controls two or more elements, and only one of the elements doesn’t work, then we know that the switch and all the wiring leading up to it are fine. The problem is either a broken element or a broken connection between the switch and that element. Identify which of these possibilities is the problem and replace the faulty part. If more than one element is not working, then the problem could be a faulty switch, connection or element. Determine whether each element in the group is independently wired to the switch (parallel wiring) or if the elements are all connected together as one long circuit (series wiring). If the ele­ments are wired in parallel, then it’s likely that the problem is either the switch itself or a connection leading to the switch. If the ele­ments are together in a series, then it could be the switch, a connector or any one of the elements. Identify the broken part and replace it.

Figure 1

To properly maintain your electric kiln, keep the right tools in your studio (from left to right: needle-nose pliers, wire strippers or a sharp knife, wire crimpers, wire cutters, adjustable wrench, screwdrivers, masking tape. (Note: Check all the types of screws used in the kiln and make sure you have the right kind of screwdriver for each type.)

32

Th e Wo r l d o f El e c t r i c K i l n s

2. If your kiln uses an electronic con­troller, then your switches have likely been replaced by relays. As above, identify how many ele­ments are controlled by each relay, then go through the same logic. If it’s just one element, check that element and its connections. If it’s more than one element, check the appropriate relay and its connec­tions.

Problem: Kiln reaches temperature but fires unevenly.Solution: Test the elements with paper as above. If all the elements seem to work and the kiln or the ele­ments are new, then consult your supplier or the manufacturer about specific characteristics of that kiln. Some kilns are intentionally designed to fire hotter in one section or anoth­er for reasons that may not be imme­diately obvious to you. Your supplier should be willing to spend the time to help you alter your firing schedule to accommodate this.

If the kiln has been gradually get­ting more and more uneven, analyze your firing schedule. Do you normal­ly have some of the elements turned

Figure 2

Spare parts you need to keep on hand toavoid unwanted delays in firing:• At least one of each type of element

used in your kiln (check model and volt­age). Some kilns use different elements in the top, bottom and center, and they cannot be mixed.

• Switch(es). Use the correct model, type and voltage rating for your kiln.

• Switch wire. Use only wire that is rated for your kiln.

on longer than others in order to accommodate preheating the kiln overnight, or to even out tempera­ture? If so, you’re probably working those elements harder than the rest and they will naturally wear faster.

If some of the elements do not pass the “paper test,” then follow the same procedure in the previous prob­lem to determine whether you need to replace an element, a switch, a relay or a connector.Problem: Kiln-Sitter® doesn’t shut off properly.Solution: Assuming that you are set­ting it properly, and that you already know how to use cones, check the following:1. Is the sensing rod bent or worn

thin? If so, replace it.2. Does the sensing rod travel freely

or is something preventing it from falling? Remove any obstructions and do not place any ware within 1 inch of the rod when loading the kiln.

3. Are the cone supports bent, or do they have some old melted cone stuck to them? Replace damaged cone supports.

• Connectors. Most common are ½-inch “faston” connectors for relays and infinite switches; ring connectors for Kiln-Sitters® and LMH (lo-med-hi) switches; and some type of brass or copper connector for the element tails.

• Relay (used with controllers and some kilns with Kiln-Sitters®). Check model and type.

• Complete tube assembly if your kiln uses a Kiln-Sitter®.

• Couple of thermocouples if your kiln uses an electronic controller. Check model and type.

4. Is the gap between the claw and the trigger properly set as per the manufacturer s instructions? Adjust as needed.

5. Is the porcelain tube assembly cracked or broken? Replace as needed.

Problem: Electronic controllershows incorrect temperature. Solution: Check the thermocouple and its connections. If anything is loose or potentially touching metal, remedy this. If the thermocouple is bent, broken or worn thin, replace it. WARNING: When replacing the thermocouple, be sure to determine which side is positive and which is negative—forgetting to check this could have disastrous results, such as a potential overfiring.

Make sure that you get the correct thermocouple for your kiln. There are several types available, and not all controllers can use all thermocouple types. Ensure that you use the ther­mocouple that your controller will accept, and that your controller is programmed appropriately for it. If the controller has been programmed for a different type than what you installed, the temperature reading will be incorrect. Also, if your controller uses more than one thermocouple, consider replacing them all at once— an old thermocouple will read tem­perature differently than a new one and could be responsible for firing your kiln unevenly.

Figure 3

A simple test to check the elements is to place a small piece of paper in each one, then turn the kiln on to its highest setting and make note of which elements make the paper begin to smoke and which ones do not.

Pottery Making illustrated 33

Th e Wo r l d o f El e c t r i c K i l n s

by Jeremy Willis

It is very beneficial to have an understanding of the basics of heating elements and how heat is distributed within the typical studio pottery kiln. Here is a brief look at these topics:

The most common type of kiln elements for studio potters are made of open coiled resistance wire. There are two primary types of resistance material that are used: nickel-chrome (NiCr) and iron-chrome-alu- minum (FeCrAl). The grade of NiCr used in these applications is 80-20 (80% nickel, 20% chrome), and is capable of reaching temperatures as high as 2190°F/1200°C. NiCr has the advantage of not deforming when its heated, so that it requires only intermittent support. FeCrAl comes in a variety of grades, and is capable of reaching a temperature of 2550°F/1400°C (Kanthal’sA-1 alloy, for example).This is the standard wire for pottery kilns. In addition to a higher temperature capability, FeCrAl requires less wire to achieve the same heat as NiCr, which translates into lower element costs (approximately 30% less for the material component). FeCrAl elements must be com­pletely supported, however, as they will deform when hot. Usually, grooves are built into the walls of a kiln to fully support the element coils. FeCrAl also becomes brittle once fired and must subsequently be handled with care. The easiest way to tell FeCrAl from NiCr is with a magnet—FeCrAl is magnetic and NiCr is not.

Coiled wire elements are relatively easy to fabricate, and some people wind their own, though commercial­ly fabricated elements are readily available.

Tip: According to Kanthal Corporation, a major producer of kiln wire, you can protect iron-chrome- aluminum (FeCrAl) elements from the effects of harsh environments by pre-oxidizing them. To do this, fire the kiln empty to 1922°F (1050°C) and maintain the temperature (soak) for several hours (7-10 if possible). To enhance the oxidation, allow good air flow into the kiln by leaving the peephole open or exhaust fans on. If you are doing reduction firings in an electric kiln, you should periodically re-oxidize the elements to increase life expectancy. The results of element condi­tioning can be quite dramatic. It may not have much effect for normal, low-temperature firings, but can be significant for harsh operating conditions.

Jeremy Willis is a professional engineer and has been designing electric kilns for artisans and for industry since 1984. He is a managing director of The Pottery Supply House Limited and the manager of Euclid’s Elements.

Heat in a kiln is transferred in three possible ways: (1) con­duction (heat is transferred through physical contact); (2) con­vection (heat rises through the air in the kiln); and by (3) radia­tion (heat emanates from a heat source).

At lower temperatures, convective heating is predominant; as the temperature increases, radiation becomes more prevalent. For this reason, element placement is less critical for low-tem- perature applications, as there will be some mixing effect. Direct venting (whereby a small volume of air is continuously drawn from the kiln during firing) is particularly beneficial in low-tem- perature kilns, as it helps to move air around the kiln (it’s also very desirable for decorating, especially decal firing, as it refreshes the oxygen in the kiln). At higher temperatures, it becomes more important to distribute the heat within the cham­ber through element design, to provide for even radiant heating.

34

Pottery Making illustrated 35

36

T h e Wo r l d o f El e c t r i c K i l n s

by JefF ZamekHaving adequate ventilation for electric kilns pro­

motes a safe work environment. There are three basic types of ventilation—updraft, downdraft and cross- draft—and any of these systems would aid the potter in venting their own electric kilns.

Why is venting important? Apart from the some­times objectionable smell encountered in the first stages of firing, there can be several potentially harmful emissions released when clay and glaze materials are heated. There has been increased concern over limiting or eliminating any health or safety hazards in the work­place or home, and almost every day we hear of risk factors to our well-being. With such a high degree of information and awareness, it’s only common sense to investigate our workplaces and recreational activities. The goal should be to incorporate any safety measures to ensure low risk to ourselves and others.

When working in ceramics, we all come into direct and indirect contact with clay and glaze materials. Specifically, clay goes through several transformations when heated to progressively higher temperatures. Mechanical water is driven off at 212°F, followed by the release of chemically combined water. While these “hidden” effects are not noticed by the potter, other changes in the clay are more apparent, namely, the oxi­dation or organic matter present in some degree in all clays. Organic matter in clay can take the form of pieces of wood, leaves, coal, binders, paper or any other combustible material. When exposed to enough heat, the organic material burns and releases particles and gases, carbon monoxide being one of the most objec­tionable.

In addition, the “rotten eggs” smell often encoun­tered in bisque firing is the result, in part, of small amounts of sulfur found in the clay being oxidized. The actual amount of sulfur can vary from one type of clay to another. For example, ball clays and stoneware clays might have a significant amount of sulfur while kaolins might have very little or none. The amount of sulfur or any organic material found in clays can also increase or decrease within a specific type of clay from year to year or even from bag to bag.

Burning organic and sulfur compounds from the clay is good because, if left, it can cause black coring and bloating later. The idea, however, is to capture the unwanted carbonaceous materials and move them away from the studio area, and electric kiln venting systems are very effective devices for doing this.

Jeff Zamek works as a ceramics consultant, residing in Southampton, MA, and is the author of What Every Potter Should Know (Krause Publications). Contact Jeff by e-mail at FIXPOTS@aol.com.

Solutions to Clean Studio AirThere are three basic types of ventilation systems

available for the small recreational or school studio— updraft, downdraft and crossdraft. Updraft ventilation operates by exhausting smoke and fumes as they rise from the kiln, while downdraft systems draw smoke and fumes out from the bottom or base of the kiln. Each of these systems utilizes a fan connected to duct work, which is vented to the outside.The crossdraft sys­tem relies on adequate ventilation within the room or studio where the kiln is operating, typically an open window with an exhaust fan.Updraft System

An updraft venting system is mounted over the top of a kiln. Updraft systems may be custom built by a heating and cooling contractor, or they may be pur­chased ready made. An exhaust hood passively removes combustible emissions and fumes generated from the firing kiln, and the kiln exhaust exits the studio via a flexible aluminum hose supplied with the system.

An updraft venting system removes fumes, smoke and vapors as they rise. This system consists of a hood with a fan, which may be purchased or fabricated, usually by a local heating and cooling contractor. The lid should be propped open during the carbon burnout period and the top peephole should be left open during the firing.

Pottery Making illustrated 37

Th e Wo r l d o f El e c t r i c K i l n s

Downdraft SystemA downdraft ventilation system

vents smoke and fumes from the bottom of a kiln. To achieve this in an electric kiln, holes must be drilled in the top of the kiln, typically in the lid, and along the bottom or in the base of the kiln. A collector or plenum is added to the bottom or base of the kiln and an electric fan (located on the kiln or nearby) draws off fumes and vapors. The system actively draws fresh air from the holes drilled in the top of the soft- brick kiln, and exhausts them to the outside.

Crossdraft VentilationBefore popular venting systems

came onto the market, a common method of curtailing electric kiln fumes was to open the windows of the studio and create a crossdraft. Many potters still use this “low- tech” method, together with a house fan, to circulate air within the kiln room. Is this old method safe? It has been proven that the newer venting systems do remove greater volumes of unwanted kiln exhaust than just opening the studio windows. Winter months and the variable factors of air flow within any given kiln room dictate another approach to clean air. Consequently, the best course of action is to take advantage of the new highly efficient venting systems currently available to potters.

A downdraft system draws unwanted fumes, smoke and vapors from the bot­tom or base of the kiln. A system, devel­oped by the Orton Foundation and pro­duced by a variety of manufacturers under license, operates on the principle of removing just the fumes and smoke and none or little of the heat.

A crossdraft system relies on fans locat­ed near the kiln to move air from the sur­rounding area out through a nearby open window or door. This method, while not as sophisticated, is better than no venti­lation at all. The lid should be propped open during the carbon burnout period and the top peephole should be left open during the firing.

For More InformationWhat Contemporary Studios Need to Know About

Venting and Firing a Kiln, booklet by The Edward Orton Jr. Ceramic Foundation, PO Box 2760, Westerville, OH 43086.

An Educational Guide to Kiln Safety; video by Vent-A-Kiln Corporation, 621 Hertel Ave., Buffalo, NY 14207.

Designing a Kiln Room, booklet by Skutt Ceramics Products, Inc. 2618 SE Steele St., Portland, OR 97202.

Safety Tips for Electric Kiln Venting

• Place the kiln in an area that can be adequately vented and away from regu­lar studio activities.

• The kiln should stand on a noncombustible surface and away from any walls. Always follow manufacturers’ rec­ommendations on kiln placement.

• If the kiln does not have a venting system, open the windows and use a fan to create a crossdraft in the kiln room.

• Before using a kiln venting system, carefully read and understand the manufactur­er’s installation and operat­ing instructions.

• In any kiln venting system, always exhaust outdoors.

• Periodically check and maintain the condition of any kiln venting system.

• With any venting system, keep the electric power cord away from the kiln.

• Electric kilns are not designed for burn-out fir­ings, so do not place large amounts of combustible material in the kiln. Electric kilns can accept wax on pots, organic material found in clays and organic binders used in glazes.

• While heavy smoke or smell from an electric kiln during firing indicates insufficient venting, keep in mind one of the byproducts of burning organic materi­als found in clay and glaze material is carbon monox­ide, which is colorless, odorless, and dangerous. Always create a kiln room environment where there is adequate air circulation and ventilation.

38

Pottery Making illustrated 39

40

Getting to Know the ClayFirst, I have the students become

familiar with the feel of the clay. To do this, I have them cut a chunk of clay that will, when patted into a ball, fit comfortably in their hands. (Tip: I use clay that has been extruded from a de-airing pugmill so that the students don’t have to learn to wedge clay on the first day. Otherwise, a short description of wedging is required.)

I then have the students pat or slap the clay into a ball to help them get a sense of the feel of the clay (see photo 1). At this point, I wander around the room to “check” the clay balls and praise the students on how round their pieces are. This encourages them, giving them a small, but important, sense of success.Getting to Know the Wheel

I next introduce them to the physical aspects of the wheel and the bats that sit on the wheel. I tell them to put their clay balls down,

Years ago, I was one of the slowest students in my ceramics class to learn to center. As a result of my own frustrating experience, I’ve developed a method of teaching students how to center clay on the wheel that is nearly 100% effective and relatively frustration-free.

get a bowl of water and a bat, and take a seat at one of the wheels. They are then told to “slam” their ball of clay onto the bat as close to the center of the bat as they can (see photo 2). Again, I check the progress. If a student is terribly off center, I encourage him/her to take the clay off the wheel and reshape the ball, being careful not to add air bubbles. Once all the students have their clay on the bat in a close-to- center mound, I explain that squeezing in on the clay causes the mass to become taller and pressing down on it forces it to become wider. Explaining this helps stu­dents understand the next con­cept—pressing and squeezing at the same time causes the clay molecules to compress, moving them to the center and compacting them. This helps to center the clay, and it makes the clay a more homogenous mass.

I demonstrate several centering techniques, showing where the hands may be placed, how the water helps relieve the friction and,

basically, how one manages to cen­ter the clay with one’s mind since the mind controls the hands. For some students, this does not make sense, but the talking helps calm their fears and encourages them. I don’t have any illusions about the talk I give at this point, but I feel that it’s important to show that there are a number of ways to cen­ter and that each potter develops his/her own technique for center­ing and throwing.Centering

Next, I sit across from each stu­dent one by one. I have the students wet the clay, telling them that this cuts down on friction and makes the clay easier to work with. As they start the wheel spinning and place their hands on the clay, trying to center, I wait and watch to see what they are doing right and what they are doing wrong. Then, after trying to talk them through the major problems, I gently lay my fingers on their hands and, through their hands, begin to center the clay (see photo 3).

Pottery Making illustrated 41

by George Juliano with Elizabeth HudginsAn Easy, Painless Method to Teach StudentsHow to Throw a PotE d u c a t i o n :

Then I have them start the wheel and follow my lead in opening the piece. I do the work, but they feel the entire process as I do it from the perspective of the potter. As I press my finger in and down, they follow the same thing with their finger (see photo 4).

When the hole seems to be within ¾ inch from the bat, I tell the students to remove their hands very slowly and gently from the clay then stop the wheel.

At this point I introduce the first tool other than water—a needle tool. I have each student measure the thickness of the bottom by sticking the needle tool into the clay and measuring the depth (see photo 5). If it is thicker than ¾ inch, I have them continue opening; if it s too thin, I have them start over with another piece of clay. Again they are told to wet the clay a bit so that the opening can be accomplished with the least amount of effort, and I show them how to open the center to form the beginning of the cylin­der.Forming and Shaping

Once the opening is made, I ask the students to watch me do my first pull on a separate wheel. Then I have each student sit across from me and have each place his/her hands in the correct position for opening the pot. I then assume the same position on their pots while sitting across from them.

I then begin to open the pot and make the first pull. This lets the stu­dents feel the way that one begins to work with the clay. I’m con­vinced that pottery is the art of touch rather than sight, and this experience of “sharing” the open­ing and initial pull gives the stu­dents the chance to feel the clay and the work of the potter’s hands on

This technique helps students relax and begin to experience what the clay feels like when its cen­tered. I sometimes tell students to close their eyes so they can concen­trate on the sense of touch at this point. It takes just a few seconds in most cases, but the feeling of the clay coming into center in their own hands leaves such a clear impression that most don’t need my help a second time.Opening

Then we move to the next step—opening the pot and begin­ning to throw the cylinder. Now that the clay is compressed, centered and ready for opening, I tell the stu­dents that trying to press a hole straight down into the clay mass won’t work. The clay is so compact­ed that it would have no place to go as their finger tries to drill the hole. The clay would, I suggest, “rebel” by shoving up beside the finger doing the opening, causing both the finger and the clay body to go off center. To keep this from happen­ing, I encourage students to go in at an angle at the top and then go down. This will result in the piece having a narrow, funnel-shaped hole, with the top wider than the bottom. The clay has room to move into the more open funnel top as needed, thus keeping the finger on center for the opening.

After they watch me open a pot, I remind them that water makes this entire process easier. I tell them again to be very gentle but firm with their clay. Rapid movement, I instruct them, causes the clay to get “skittish” and “jump” or move off center.

I then sit across from the student and place my hands in the correct position on the clay. I have them do the same thing; on the other side.

42

Pottery Making illustrated 43

that clay. As I work, they generally get the feel of how the clay is pressed in at the outside bottom of the side and then moved gently up the cylinder, adding height and making the walls thinner as we go. Again, they learn this through feel­ing the clay (see photo 6).

At this point, I ask them to do the next pull, reminding them to be gentle and to release very slowly. I keep my hands on the pot and this time feel how they are working. I give them advice as necessary and encouragement where possible. Once I know that they have the general idea and have gained some confidence, I move on to the next student and let the first student continue pulling the pot until it has even walls and is ready for shaping. I then have the students stop their wheels and wait for the entire class to be ready to learn how to shape.Finishing Up

When the students all have their pots fairly well finished, I have them smooth the rim with a piece of wet paper towel (see photo 7).

Then I show them how to trim the bottom a bit so that they’ll have less work to do when the piece is leather hard and ready for the “serious” trimming (see photo 8).

At last, the students then are shown how to cut the piece from the bat, and I watch as they do the

cutting, reminding them to hold the wire tightly so that it stays close to the bat and taut (see photo 9).With the initial work complete, the stu­dents can see their pots and feel a great deal of success, and look for­ward to trimming, firing and glaz­ing in a few days.

Over the 25 years I’ve worked with ceramics, I’ve found the method of placing my hands with the students in the same pot at the same time, to be the most effective in teaching them to center, open and throw a pot.

George Juliano is a full-time ceramics teacher at Robinson Secondary School in Fairfax, Virginia. He has had several magazine articles published on pottery making, and he is currently teaching two graduate school classes for Virginia Commonwealth University (e-mail:gjuliano@erols.com)Elizabeth Hudgins is a retired high school English teacher and has had a number of articles and poems published, (e-mail: ehudgins@tidalwave.net or www. tidalwave. net/~ehudgins)

44

Pottery Making illustrated 45

K i l n s a n d F i r i n gIt’s not unusual for a pottery student to spend years learning to

shape and decorate clay without ever putting it into a kiln. The first step toward independence as a potter is to learn about kilns and firing. Firing is integral to the process of creating pottery— making a pot without understanding the firing process is like try­ing to make cookies without knowing how to use an oven. Even as a student with no immediate intentions of setting up a private studio, understanding the different types of kilns and the many ways pottery can be fired will help you make informed choices

about materials and techniques. The books listed here will be of use to different people in different ways. If you already have, or have access to, a kiln, some of these books may help you get the most out of it. If you’re considering investing in a kiln, there are a number of books that can help you decide what type(s) of kiln you need, and whether to build or buy one. If you’re a stu­dent with no desire to take on the burden of firing your own work, the following books may help you choose not only the materials you will use but the classes you may want to take.

Ian Gregory— K iln BuildingOviedo, FL: Gentle Breeze Publishing, 1995

This book is a quick summary of the con­ventional wisdom regarding the design of fuel-burning kilns, with one chapter covering experimental kilns. The text is relatively short and easy to read, making this a good first book if you’re considering whether to build a kiln, or are just curious about the process. Gregory

covers the choice of fuels, kiln types, materials, and construction methods, and offers plans for 13 types of kilns. Presumably because the author is British, most of the plans are for oil rather than the gas kilns most commonly used in the United States, so they may not be suitable for most readers. However, if you’re building a kiln, you probably need to design it to suit your own requirements, rather than relying on a plan from a book. For any­one who is serious about building a kiln, further reading in amore comprehensive book is probably a good idea.

Harry Fraser— The Electric K iln: A Users ManualA&C Black, London, 1994

If you want to fully understand how an elec­tric kiln works and how to use it correctly and safely, this is the book for you. It contains little information on which clays or glazes to use in oxidation though there is a chapter on special

effects (reduction, crystalline glazes) and on defects in fired ware, with an emphasis on how to change the firing process to avoid or correct such problems. The American reader of this book will need to keep in mind that it is written in England and therefore any dis­cussion of power supply and regulation may not be relevant. However, most of the kilns discussed are made in the U.S. and oth­erwise the information is accurate and up-to-date. Fraser does take care to point out differences between the U.K.and the U.S. in mat­ters such as the color-coding of live, neutral and ground wires, potentially a source of great confusion. This book is intended to help you choose, install and maintain an electric kiln, including some basic repair and trouble-shooting suggestions. If you’re nerv­ous about buying a kiln, by all means read this book.

NILS LOU-------The Art of F iringOviedo, FL: Gentle Breeze Publishing, 1998

Nils Lou is an experienced potter and kiln- builder with an obvious love of the firing process, an urge to experiment and an intu­itive grasp of what is happening inside a kiln. This book is a highly readable presentation of principles of efficient kiln design and usage

arrived at through experience and experimentation. While other books teach kiln construction techniques, Lou discusses the firing process, and suggests ways in which conventional kiln design can be modified to improve kiln efficiency and achieve reliable results. In addition to the construction and firing of the conven­tional gas kiln, Lou covers salt and wood kilns and various appli­cations for refractory coatings. Anyone who fires a kiln will learn something from this book, and if you’re planning to invest in a fuel-burning kiln, whether building or buying it, you will find it helpful as well.

Frederick Olsen— The K iln Booklola, Wl: Krause Publications, 1983

Anyone planning to build a kiln should cer­tainly read this book. Though I wouldn’t rec­ommend building a kiln based solely on instructions in a book without the help of an experienced advisor, this is a good starting point and reference. This book will help you

decide what type of kiln to build and what materials and equip­ment to use. The many charts, tables and formulae are worth the purchase price, allowing you to calculate things such as how many bricks you will need and how many burners, and of what size. Olsen even includes instructions on building an electric kiln, though most readers are more likely to be interested in building gas or wood kilns. Though there are a few plans included in the book (mostly of historical kilns), the author’s intent is to impart basic design principles and construction techniques, which you can use to design a kiln for your needs. Be aware that, though this book is still in print — a testament, after seventeen years, to its enduring use­fulness - some of the information may be outdated. In particular, some of the design principles have been questioned or modified by potters such as Nils Lou (see The Art of Firing, above).

46

Katy McFadden, an instructor at Clackamas Community College, in Oregon City, Oregon, and Don Adamaitis, providing technical help, conducted a 2-day raku kiln-building workshop during the 1999 summer session. The workshop participants followed the directions in the Pottery Making Illustrated article

“Building a Domed Cylinder Kiln—Part I,” published in the Summer 1999 issue. Each participant con­tributed to buying the materials required and a total of five kilns were built. Katy McFadden later conducted several raku-firing demonstrations with some of the participants using the kilns they had built.

Day 1The construction of the wire-frame support form. The instructor, Katy McFadden (right foreground) and par­ticipants are shown clipping the domed overhang wire-mesh screen to the circumference of the cylinder.

Day 2Completion with the installation of the high- temperature fiber blanket and applying the high-temperature safety coating to the kilns. Participants are shown installing and com­pressing the high-temperature fiber into place.

Day 2 (continued)Participants are installing the ceramic studs and will later cut the vent hole before spraying the kilns inside and outside with the high-temperature coating mix.

R ichard Zakin— Electric K iln Ceramics : a Guide to Clays and Glazeslola, Wl:Krause Publications, 1981

The first or second piece of equipment a potter purchases is often an electric kiln. A gas kiln may be out of range or impractical

for many just starting out in the craft, but anyone can install a small electric kiln in the home. This book will explain how to use the kiln, offers suggestions on clays to use and includes glaze recipes specifically designed to function best in the electric kiln. Zakin also gives the reader interesting and inspirational glimpses into the working style of many contemporary ceramists working in oxidation. This book does not go in depth into how an electric kiln works or how to build or repair one, but focusses on how to get the most out of your kiln. Zakin does discuss choosing a kiln and taking care of it, and includes suggested firing schedules. He discusses the use of the Kiln- Sitter® and timer mechanisms, as well as programmable firing devices, information that will help in choosing a kiln and dif­fuse some of the trepidation a first-time kiln buyer will natu­rally feel.

A potter for 20 years, Sumi von Dassow teaches pottery at the Washington Heights Center for the Traditional Arts in Lakewood, Colorado, and is a frequent contributor to Pottery Making Illustrated. Visit her web site at http://www.well.com/~sumifor more information.Pottery Making illustrated 47

48