TS I

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I N t 1 I. I I & BOLTS

Debunking water= base

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Considering a conversion t o water-based printing, my fr iend Liz did some reading, made some phone calls and did some more reading - she's a very thorough human being. A t the conclusion of her

research, she called m e denouncing the confl ict between reports she'd read in the trades and information she'd received from var-

ious chemists, t h e SPAI, waste-water treaters and her suppliers (of which I am one), about water-based inks. So I paid her a call to check out this suspicious documentation. She threw down the

offending magazines and said, "According to these, you can wash it down the drain; they say using water-based i s t he 'environmentally

correct,' thing to do and tha t it performs as wel l as plastisol." I read the articles and saw the problem: they didn't really say these

things, but they certainly implied them. After I interpreted the "fine priht," which more o r less aligned it with what she'd learned f rom her other sources, Liz said, "Hey, you wri te articles. Why not

wri te one about water-based printing? But don't imp/y anything - spell it out." So I called Printwear, and here w e are.

Hope you like it, Liz!

by Glenn Shull

98 PRINTWEAR MAGAZINE MAY 1993

Liz isn’t the only one confused about the re-birth of water-based (W-B) inks and the destiny of plastisols. So, through simple terms and “Straightforward Facts,” I aim to dispel some myths, provide practical pros and cons and consider var- ious areas of the shop affected by a con- version to W-B printing.

I t ’s in the water Right up front, let’s tackle the most

discussed (and controversial) issue: envi- ronmental safety.

Straightforward Fact #1: It‘s the print- er‘s sole responsibility to investigate the limits of emitting waste porn his building. In the case of waste-water, it’s best to enquire directly of your treatment plant. I f you’re on a septic system, don’t pu t any screen-print waste down there. Period.

Straightforward Fact #2: Waste-water treatment plants are where pollution is detected, and they have means to track i t back to its origin, to levy penalties and to shut you down. So don’t rely solely on product

labels or Material Safety Data Sheets (MSDSs) when assessing the compliance of your dis- charges.

Straightforward Fact #3: Use a little of whatever product you’re curious about, collect the waste water and have i t tested. This is the only best way to convey your needs to the water treaters.

(Note: Learn more about the above Straightforward Facts in related feature, page 138, this issue.)

The surest policy is to acknowledge that it’s a very complicated ballgame. So don‘t rely on ink makers‘ claims any more than on MSDSs. If there’s a violation, the manufacturer won’t be fined ... you will.

Airborne pollution Discharging waste product into the air

opens yet another can of worms to which a switch to W-B inks has relevance.

Straightforward Fact #4: Textile printers have very little to worry about in terms of volatile organic compounds (VOCs - often, a reference to solvents). The worst-case

MAY 1993 PRINTWEAR MAGAZINE 99

c

scenario is Southern California where one gallon ofproduct may only contain three and a third pounds of VOCs.

Straightforward Fact #5: A W-B ink may have more VOCs than a plastisol. Most plastisols are 100 percent solids, while many W-B inks - though not all - still utilize sol- vents. Yet even a solvent-bearing W-B will probably have lower VOCs than Southern Calfs limit-per-gallon.

ust like the Pank robber who faces

a penalty if caught, so does the

screen printer who flaunts EPA

and OSHA regulations.

/ J Solid, man

Discharging waste into the solid stream - ie: the dumpster -is a sticky one. If you can’t throw it in the trash, just how do you get rid of dead ink stock? I mean, plastisol or W-B, you can’t wash it down the drain. So you’ve got to throw it away. Right?

Straightforward Fact #6: Wrong. A t least not into general trash that‘s destined for the landfill. But prudent ink management will produce significantly less dead ink. And what is produced can be recycled in many ways. A lot of supposedly dead ink can be rein- carnated through dispersal into other colors. Mix together, for example, all your dead blues; no matter how ugly this mixture looks, i t can usually be toned into Navy, turquoise or aqua. w

The bottom line is this: just switching to W-B inks does not make you a good guy with either the EPA or OSHA.

Straightforward Fact #7: It’s all in the way you handle the products. My belief is that just about anything is safe if handled properly. And don’t take for granted what anybody tells you (including me!) unless they’re from OSHA or a branch of the EPA.

StraightforGard Fact #8: A conversion to W-B inks can be motivated by a variety of pros - soft hand, lower ink cost, ease of wash-up and so on. But there are just as many cons. So understand that W-B can’t do everything plastisol can do any more than plastisol can do all that W-B can do.

The people factor As you see in your MSDSs, textile inks

have very low HMIS ratings - 1,0,0 or l,l,O - so direct human exposure to the ink is not much of an issue as long as workers follow the personal protection index accompanying the HMIS rating. The biggest W-B issue regarding employee exposure concerns the zincformaldehyde-

100 PRINTWEAR MAGAZINE MAY 1993

Peek- e- boo: The

transparency of

water- based ink

allows for very

clean, bright

colors; concepts

depending on

striking color con-

trasts or blends

have proven very

successful. What‘s

more, solid areas

can typically be

overprinted to pro-

duce tertiary

colors.

sulfoxylate (ZFS) that enables most dis- charge ink to do its thing. Thus:

straightforward Fact #9: I f it smells like formaldehyde, looks like formaldehyde, walks like formaldehyde and talks like formaldehyde ... hey, i t might be formaldehyde.

If you’re printing with a ZFS-bearing discharge system, monitor your employees’ exposure to it by having them wear clip-on sampling devices for a shift, then having the devices analyzed. The results will tell you what, if any, action to take - such as continued badge moni- toring, improved dryer exhaust, better ventilation in or even enclosure of your printing area. Even without using dis- charge inks you may have formaldehyde exposure in your shop. Some garment makers use the stuff in dying and fin- ishing, and it goes airborne when run through the dryer. (Don’t be surprised in the future to receive MSDSs on garments made expressly for post processing.) Could be that neither source of formaldehyde alone will produce actionable levels, but both together may.

Straightforward Fact #lo: Air sam- pling analysis can save your butt in a liability suit regarding employee exposure.

I don’t intend this to be a shooting match between W-B and plastisol or a rec- ommendation to convert or to stand pat. (I’ll leave such matters to the ink compa- nies.) But if you do decide to convert, below are some practical parameters - from art prep to QC - for successfully employing W-B ink in your shop.

Art preparation The goal of any art plan is pre-

dictability on the shirt. Because W-B inks have different printing characteristics, when engineering art or assessing cus- tomer-provide art, you must anticipate the outcome, just as you (hopefully) do with plastisol. Certain art may reproduce poorly. End-print characteristics may not meet a customer’s expectations. Advance warnings about multi-colored grounds, fiber show-through after washing and lim- itations of fine detail* will save many a “debate” with a customer (after 1000 or SO

shirts have cleared the dryer) -it’s clearly better to educate your customer about W-B’s potentials and limitations before printing begins,

For example, W-B inks are generally

*(See mesh and stencil considerations below.)

102 PRINTWEAR MAGAZINE M A Y 1993

not opaque. This limits the eligibility of dark grounds, save with discharge ink. Lack of opacity also should be considered when deep trapping with black will be necessary. The colors beneath the black trap may be visible. Low opacity also con- tributes to a change of ink hue when a given design is printed on grounds of dif- ferent color, even if they‘re all “lights.”

This transparency does allow for very clean, bright colors; concepts depending on striking color contrasts or blends have proven very successful. Since W-B inks absorb so well into the fabric, halftone overlays, used to achieve “non-printed” colors, aren’t always necessary; solid areas can typically be overprinted to produce ter- tiary colors.

’ ith the advice of the local

Fire Department - who

carefully studied all my

MSDSs, then made safety rec-

ommendations - I survived

a surprise OSHA inspection with flying

colors. ,

Screen making Since the water component of a W-B

ink is driven off in the drying process, the printed ink film decreases in thick- ness an equivalent percentage when dried. This dictatesa thicker lay down than might be expected with a 100 percent solids ink.

Thus, mesh- and stencil-selection rules of thumb will change a bit. Monofilament polyester is still the favored mesh - nylon, due to its affinity for water, must be avoided. W-B inks tend to prefer a more open mesh (60-125). Meshes coarser than 60 may be used if your ink has a large

solid in it s w h as a glitter or pearl flake. The basic rule for W-B (including dis-

charge inks) mesh selection is the darker the garment, the lower the mesh count. A reasonable average mesh to consider is a 110. Higher counts can be used - up to 225 and even a notch or two higher - for halftone and process work, but the grade of ink in such cases will be the factor that determines success; if your ink, for

104 PRINTWEAR MAGAZINE MAY 1993

Coarse for the par:

The basic rule of

thumb for W- B

(including discharge)

mesh selection is: the

darker the garment,

the lower the mesh

count. in fact, W-Bs

tend in general to

prefer more open

meshes (60-125).

example, dries quickly, forget the finer mesh.

When using a W-B system - even more so than with plastisol - as the stencil goes, so goes production. If a sol- vent-resistant stencil is improperly processed, you can sometimes get by; but if a water-resistant stencil is shortchanged, it will die.

Remember back in Chem 101 how we learned that water was a “universal sol- vent‘’ and that, given time, it would break down most anything? Well, this includes stencils. (Coincidentally, the upsurge in W-B ink usage has actually spawned an improvement in stencil processing industry wide.)

Many printers - even those who aren’t printing W-B - have embraced water- resistant emulsions and films as a hedge against humidity. Although stencil failure due to under drying often mimics an under-exposure problem, don’t be fooled. Weak stencils most often result from mois- ture that isn‘t evacuated prior to exposing. What’s more, ambient humidity impedes this evacuation. Water is naturally attracted to m y dry environment and, conversely, does not find wet environ- ments at all appealing. Thus, if the air is full of water (high humidity), that which is in the stencil has no reason to leave. A drying cabinet or climate-controlled (40- 50 percent relative humidity) drying room is mandatory, but it alone is not enough. The exposure area must also be humidity

controlled, for if you take a bone-dry stencil into a moisture-laden room, it will suck up water faster than the IRS sucks up paychecks. (In fact, I’ve been known to kid -no doubt in poor taste - that the best way to dehumidify a room is to carry a nice dry screen into it.)

A mistake I see lots of printers make is failing to sufficiently dry their block-out; because, just like the stencil, W-B block-out is emulsion (since most stan- dard block-outs happen to be water-sol- uble), it too will break down. Thus, remember to let it adequately dry during your post expose.

Finally, as in any type of screen printing, the stencil is the image. But with W-B printing, short cuts that may have squeaked by before just won’t fly.

(Note: To learn more, refer to the author’s examination of water-resistant stencils in his first “On Target:” column, January PW, page 22.)

Production The actual application of W-B ink is

easy; the primary struggle (especially for plastisol veterans) is against drying in the screen. A high-grade ink with a dash of wetting agent will stay open in an idle screen for 20 minutes; one or two sample passes will completely free the image area when production resumes. If you remember to “park” your press in the flood position both when you take a break and during a run - using a squeegee-

1 ’ 106 PRINTWEAR MAGAZINE * MAY 1993

ischarge

inks are

water- / based D products

containing a

component that

destroys the gar-

ment’s dye and

replaces it with the

ink*color. If every-

thing i s properly

controlled, dis-

charge i s a pretty

slick process.

flood, squeegee-flood sequence, rather than the other way around - the ink over the image area will stay wet. A thin ink residue, though, will dry and clog quickly.

The beauty of W-B is its ability to print wet-on-wet forever with little build-up and no flashing. The low viscosity and open meshes used allow for fast squeegee speeds. Translation? Faster production.

Curing Curing W-B ink is first a function of

driving off the water - the pigment/ emulsion will not heat-set until this happens. Sound easy? It is if you have the right equipment. Any heat source can steam water; the trick is getting rid of that steam. As with the emulsion-

drying scenario above, the water in the ink film has nowhere to go if the dryer environment is full of water. Once the ink film is more dry than its environ- ment, it tends to suck available ambient moisture to itself.

Unfortunately, the typical IR dryer just can’t hack W-B ink. It lacks the necessary air flow to evacuate humidity from the drying chamber. Thing is, you’ve just turned your press into a Lamborgini, so don’t drive it in a parking lot. Why not take her out to the open road where you can punch it, Myrtle? Gas-fired dryers rep- resent the open road - and, just like that open road, they’re longer than a meager six feet.

Gas dryers heat the air, then circulate

1 108 PRINTWEAR MAGAZINE MAY 1993

Dual- system friendly:

For those in a transi-

tional condition

between plastisol

and water-based

Inks- or those who

choose to employ

both systems - this

split- belt dryer I s

designed to accom-

modate varied

drying parameters.

1 1 10 PRINTWEAR MAGAZINE MAY 1993

it in the heating chamber; additional heat typically comes from a small section of IR at the entrance. Thus, the moisture-laden chamber is evacuated 10 times faster than in most IR systems. With enough air and heat, in fact, you could set W-B ink in a matter of seconds. Since this is not eco- nomical, consider 20 feet of heat on a 48-inch belt a good size to keep up with one fast-moving automatic.

A late innovation to address potential space problems is the multi-level dryer. In it, the garment travels back and forth on a series of belts - this turns 10 feet of heat into 30. Check it out.

(Note: To learn more, refer to related feature, page 112, this issue.)

Quality control As with any printed textile, the cus-

tomer will not appreciate the ink washing out. Thus, a wash test is the only valid one for cure. An additional test many end users require is a crock test. Crock is a measure of color fastness to the garment. Rub a piece of plain fabric on the cooled ink film; if the ink color shows up on the plain fabric, you‘re in trouble. Hopefully, the ink is just not heat-set, and can be re-cured. If the ink has been overpig- mented, though, the only correction is washing. Unfortunately, customers usually won’t accept pre-washed garments. Crock-meters which measure crock to

ASTM (American Society for Testing and Materials) standards are readily available.

(Note: To learn more, refer to the author’s discussion of cure-testing, Nov. 1992 PW, page 42.)

The universal approach Changing an ink system, as you can

see, will affect all the phases of the process. One reason W-B inks have a trou- blesome reputation is that users typically fail to prepare for their use in terms of “the big picture.” W-B has many positive aspects, but simply dropping it into an existing scenario will lead to disappoint- ment. I work with all ink systems, from plastisol to UV. No matter what I’m dealing with, a conversion of ink systems is never easy; if it was, everybody would do it.

There are diTtinct benefits to be had with W-B, but I cannot stress enough: lack of preparation, listening to people who don’t know the local regulations, and not considering all the areas affected will only lead to a long and costly accli- mation period.

I wish to thonk my friend Liz, Marcia Kinter (SPAI), Maryland Air Management, Penna. Dept. of Natural Resources, Virginia OSHA and Din0 “The Hit Man” Vingino (TW Graphics), for their help and information in preparing this article. w