Good Pqinting Prqctices

Point ApplicotionChoice of Applicotion Melhod :The importance of the correct application of a coating system cannot be overstressed; if it is applied under thespecified film thickness then premature corrosion may occur . On the other hand if it is applied too thickly, thenother problems such as slow curing or cracking etc can occur. The method of application is also an importantfactor as it can affect the final appearance and performance of the paint system. Other factors to beconsidered when deciding on the method of application.

a. The Shape of The StructureA complicated structure (such as lattice work) may be unsuitable for spray application because of extremelyhigh loss factors involved and another method of application, such as roller, may be more suitable.Small diameter pipes are more likely to be brush applied whereas the coating of the internal surface ofa large diameter pipes is more suitable for spray application.

b. The Location of The StructureThe possibility of overspray onto adjacent structures or vehicles parked close to a building or structure mayprohibit the use of spraying. Also the location of an area to be coated may be such that it is uneconomical orphysically impossible to apply paint by spray in that area.

c. Manufacturer's RecommendationsCertain produce are formulated for spray application only and too fast drying for brush or roller application;other products must be spray applied to achieve the specified film thickness in one coat.

The above mentioned factors are just examples of some of the considerations that should be taken intoaccount when choosing a method of paint application.

Methods of Applicolion :There are four common methods of applying coatings to steel and other surfaces

Airless Spray

But not one of them is the "best" method for all coatings

Brush ApplicolionBrush application is not an outdated method of paint application as is sometimes thought and indeed is still thebasic method by which most decorative and maintenance coatings are applied. lt is relatively slow method butcan be the most suitable for applying paint to small complex structures and also "hard{o-access" areas. lt isalso a useful method of applying a "stripe" coat to areas such as bolts, rivets, edges, corners etc prior to theapplication of the spray-coat, so as to ensure the correct film thickness is achieved in these areas. Thebrushing action can ensure good wetting and flooding of surfaces where high quality surface preparation is notprovided. This helps to improve the adhesion of the coatings of these surfaces. There are various types ofbrushes: the flat wall type, brush which may be up to 6 inches (lScm) in width with bristles up to 6 inches(1Scm) in length; the oval brushes which are often used in the marine and industral areas for the applicationof coatings to irregular surfaces, such as rivets, raillings etc.

When applying a coating by brush the following tips may be useful to ensure an even application

Brush should not be dipped further than 1-1 1/2 inches (2.5-3.Scm) into the paint so as to prevent dripping orthe running of the paint onto the handle. Wipe the excess paint from the brush by gently tapping the bristlesagainst the side of the can.

The coating should then be spread over the substrate, holding the brush at angle of about 45'. Light strokesshould be used to evenly spread the coating on the surface followed by light parallel strokes over the surfaceof the coating to smooth the surface and eliminate brush marks or other irregularities in the surface. Alwaysbrush the final strokes from the last brush load into the previous brush load, overlapping the wet-edge so asto prevent uneven film thickness at the overlap areas.

Fast drying products require a slightly different technique where the brush should be dipped and filled andapplied to the surface as quickly as possible. Apply the coating using a few rapid strokes. Do not go back tothe coating and try to "brush it out" as it will result in uneven film thickness caused by pilling up the coating andalso unsightly brush marks. Apply the next brush stroke in the same manner as quickly as possibleremembering to brush the lapped area from the latest wet edge into the previous brush load. lf applying a fastdrying product to an edge or surface irregularity, always brush out over the edge regularly so as to ensure thecorrect film thickness is achieved in this area.

Roller ApplicotionRoller application is generally used for large flat areas such as walls, steel sheeting, etc. lt is a faster methodof application than brush but not as fast as spray application. The universal use of this method is limited by twofactors:

a. the geometry of the structure andb. certain coating which are, by their nature, unsuitable for roller application

Roller application achieves a much better finish if the surface is smooth. lf the surface is badly pitted, rustedor uneven, brush or spray application would be more suitable. Roller application does not thoroughly wet thesurface and also often does not achives the recommended film thickness. However, it is useful method ofapplication of coating with lower losses than spray application.

Dsclomer:Theabovenformatonsgiventothebestofourknowledgebasedonlaboratortestngandpractilexperen However,astheproductisoftenusedundercondtonsbeyond our control, we nnot guarantee anything but the quality of the product tself We reserued the right to change the gven informaton wthout prior not

The paint roller consists of a roller (usually foam, nylon or animal hair) and a handle to which it is attached. Theroller is usually about2 inches (Scm) in diameter 9 inches (23cm)long. Smaller rollers exist for small objects.The length of the pile on the roller varies lrom 114 inch (6mm)To 1 112 (40mm)depending on the material usedfor the pile. A long pile is used for rough surfaces whereas the shorther pile is used on the smoothersurfaces.

Rollers can have very long handles or poles which make their use in shipyards particularly common as theyare used regularly for touch up work where expensive scaffolding need not be employed.

Convenlionol SproySpray application of coating is the faster method of applying a paint. Conventional air spraying is commonlyused in application of coatings to cars, industrial products, and small areas of repair where a high quality offinal appearance is essential. Essentially the paint is atomised to form a mist by the passage of a low pressureair stream and liquid paint through a small tip. The air then applies a pressure to the force the liquid paintthrough the orifice of the gun and propel itto the surface to which it is being applied.

Typically the air pressure involved is 40-100 psi. By controlling the viscosity of the paint, the volume andpressure of the air supply and the tip size, a paint can be successfully applied to the surface. A high viscositycoating is better applied using a pressure feed system with a heavy duty gun whereares an automotive coatingwould use a completely different set of equipment e.g. a suction gun.

There are two method of bring in the coating to the spray gun, either pressure feed or suction

A suction feed gun is usually fitted with a "cop" or "containe/'which contains the coating to be applied. (Thisliquid have already, if necessary, been thinned to the correct viscosity for spray application). When the triggerof the gun is operated, suction developed at the tip of the gun draw paint from the cup to the nozzle where itis sprayed. lt cannot be used successfully for the application of high viscosity coatings.

ln a pressure feed gun, the coating is forced into the gun under pressure. The coating is stored in a pressurepot. This pot is connected to the gun by a fluid and an air hose and to an air supply by a large diameter hose(3-4 inch) (75-100mm). The coating is forced under pressure through the fluid hose to the gun and air supplieddirectly to the gun force the coatings of high viscosity and is faster than the suction feed method.

With all type of spraying (including airless), it is essential to have a water and oil separator to ensure that theair supplied from the compressor is clean. lf this is not provided, the result is usually premature coatingbreakdown because of contamination of the coating as it is applied.

The paint roller consists of a roller (usually foam, nylon or animal hair) and a handle to which it is attached. Theroller is usually about 2 inches (Scm) in diameter and 9 inches (23cm) long. Smaller rollers exist for smallobjects. The length of the pile on the roller varies lrom 114 inch (6mm).

Disclomer : The above nformaton s gven to lhe best of our knowledge based on laborator testing and practl experen However, as lhe product is otten used under conditionsbeyond our ntrol, we nnot guarantee anything but the quality of the product itself We reserved the rght to change the given information wthout pror notce

Airless SproyThis method of application is usually favoured for high build coating on large areas. lt has considerableadvantages over conventional spray, brush and roller methods of application in speed of work and the abilityto achieve specified film thickness in one application. Hydraulic pressure alone is used to apply coatings byairless spray , in a controlled spray pattern. The coating is atomised by forcing it at high pressure (2000-4000psitypically)through an accurately designed small office (known as tip) at different pressure and orifice size,to form a "fan" of paint droplets. A combination of high velocity and rapid expansion of the coatings on passingthrough the orifice into the atmosphere causes them to break up (atomise) without the additional assistance ofatomising air.

The pressure is supplied by either an electric or air activated pump. The air activated pump, which is the mostcommom on-site equipment, can transmit to the coating material pressures of 20-75 times the pressure of theair supplied to the pump by compressor. (Typically hydraulic cylinder ratios are 30:'1 , 45:1 and 60:1 ). Somepumps are fitted directly to a wall and are supplied by 200 litre drums, other fit over the top of a 5 litre or20 litre drums and have wheels which make them portable on site.

Special high pressure paint lines are necessary for the material to be sprayed.

Airless spray application can be controlled by the pressure, tip size and angle and the viscosity of the materialbeing applied. The recommended practice in every instance is to ensure that the most suitable spray tip andpressure are selected and tried, and to establish, prior to painting, whether any addition of solvent would benecessary. The tip size is very important as combined with the pressure they determine to flow rate of thepaint. Serious consideration should also be given to the spray angle ensuring that the optimum fan width isprovided in relation to the shape and size of the structure being coated. lt is important to ensure that all theequipment is kept very clean so as to ensure the minimum of delay because of tip blockages etc. Reversibletips are available to clean tips quickly but good housekeeping is the best way to ensure trouble-freeapplication. Some useful procedures that should be followed are:

a. Always use clean tips and clean these with solvent if application is to be stopped for more than 15 minutes.Always ensure that the tip size recommended on the product data sheet is being used.

b. Stir paints with air-driven mixers and not with pieces of wood as splinters cause blockages and also candamage the pump.

c. Use a filter on the paint intake line, in the pump and in the gun (unless specifically instructed by the datasheet to leave the filter out).

d. Keep the paint containers covered, even if the paint container is under the pump, so as to prevent dust andgrit etc getting into the paint.

e. At the completion work of each day, ensure that the pump, paint lines and gun are thoroughly cleaned withthe recommended cleaning solvent.

f. Spray Technique: The spray fan should be kept at right angles to the surface and the gun should be triggeredat the end of each pass. The ideal distance for holding an airless spray gun from the surface being coated is12-15 inches (30-40cm) as this will ensure a full wet coat is applied. Distance in excess of 20 inches (50cm)encourage pinholding, dry spray and overspray to occur.

Ensure that the safety trigger device is in working order and only released during spraying operations. Airlessspray application requires a high degree of care because of the pressures involved. When spraying it isadvisable to avoid placing hands or fingers in front of the gun as the coating can be forced into the fleshand bloodstream.

Dscloimer : The above nformation is gven to the best of our knowledge based on laborator testng and practil experence However, as the product is ofen used under conditonsbeyondourcontrol,wennotguaranteeanythngbutthequalityoftheproducttself Wereservedtherghttochangelhegiveninformationwthoutprornotce

Properly controlled airless spray is probably the most economical method of spray application. The equipmentis relatively expensive but the savings on major applications often offset the high initial coat. The use of airlessspray has several advantages over conventional spray application.

i. Airless Spray is a faster method of application.ii. Overspray is reduced to a minimum resulting in a healthier, cleaner and safer working environment.iii. Much more viscous paint can be applied.iv. Solvent entrapment is reduced as much of the solvent in the paint is lost when the paint leaves the gun.v. Providing that adequate pressure is available, more than one gun can be used with spray pump.vi. lmproved surface wetting characteristics (especially when fast drying paints are being applied).

Discloimer:Theaboveinformalonsgiventothebestofourknowledgebasedonlaboratortestngandpractlexperen Howevet,astheproductsoftenusedunderconditonsbeyondourcontrol,wennotguaranteeanythngbutthequalityoftheproductitself Wereseryedtherighttochangethegvennformationwthoutprornotice

KCC Points Sdn. Bhd.l'2t961 fl

Ihis dofo sheet supersedes oll previous issues. (LZG /17 /04/131

Good Pointing Proclices

lmportonce of Surfqce PreporotionThe cleaning and surface preparation of a substrate should not be considered as a seperate matter but as anintegral part of the coating system. The objective of surface preparation is to clean the substrate, creating asurface profile to which a coating can properly adhere subsequently. Thus, a proper and correct surfacepreparation recommendation is essential to enhance the durability and effectiveness of a coating system.

There are two main objectives to surface preparation: firstly, to remove the loose material such as mill scale,dirt, oxide films, grease, etc. from a substrate so that the coating can adhere to the surface, and secondly, toincrease the surface area of the substrate by increasing the roughness and anchor pattern of the surface. lf acoating is applied to a contaminated surface that has not been cleaned then the adhesion of the coatingsystem to the surface can only be as good as the adhesion of the contamination to the surface or the adhesionof the coating to the contamination.

l. Mosonry, Concrele ond Plqster:New concrete should be allowed to cure for at least 4 weeks before any painting commences. The surfacemust be clean, sound and dry. New plaster concrete normally has a loosely adherent layer of laitance on itssurface which should be removed by acid etching, power tool cleaning or sweep blasting. From oils, curingcompounds and releasing agents also need to be removed thoroughly as these will affect the adhesion of thecoating to the substrate. The most effective method of obtaining a satisfactory surface for painting is to blastclean carefully using a non-metallic aggregate.

Acid etching is carried out using dilute hydrochloric acid (10-15% concentration) however, on reinforcedconcrete, the use of an organic acid (eg. Muriatic) is preferred. The acid reacts with the calcium compoundsin the cement and can usually be seen to bubble. The reaction product, calcium chloride, must then be washedaway thoroughly by means of a fresh wash rinsing.

For old concrete, depending on the situation, mechanical cleaning using scarifying equipments may benecessary to be employed to remove old coatings or unsound surface layers of concrete. This method ismostly used for "repair" areas where mortars are used to reprofile the surface.

2. Wood, Plywood ond Woll Boord :Moisture content in wood materials should not be more than 15% before painting. Knots and pitches shouldbe scraped off or if still soft, shall be removed by solvent and be sealed with recommended sealant. Sandpapering to obtain smooth surface if required would be necessary.

3. Previously Pointed Surfoces:The old and composition of an existing surface coating on a substrate can have considerable bearing on howa freshly applied system will perform. Before coating, a thorough examination of the substrate is advisable andthe surface should be checked for cleanliness, chalking adhesion and / or other defects. lf the existing surfacecoating system is intact and sound, then these surfaces can generally be cleaned with a degreasing solutionand freshwater, and allowed to dry prior to painting. However, where there are areas of coating breakdown,spot repair or complete repair may be needed and one of the previously described methods should beemployed. lf in doubt, contact your local KCC representative for advice.

4. Non-Ferous MetqlsThere are a number of non-ferrous metals used in construction industry which require painting for eitheraesthetic or protective reasons; Copper, Zinc,Bronze, Aluminium, Galvanized steel etc.

Aluminium for instance is an important structural non-ferrous metal that are found in the construction, aviationand shipping industries. Adequate surface preparation is essential for these metals so as to ensure properadhesion of the paint system. Surface cleanliness is usually confined to the complete removal of oil, dirt andgrease by degreasing prior to priming with a specially formulated coating.

Golvonized MelolMany paint systems fail when applied to galvanized steel, mostly because of the absence of a proper etchingor wash primer or insufficient surface preparation. All galvanized steelwork must be thoroughly degreasedwith an emulsifier degreaser.

The acidic copper solution reacts with the galvanized steel and turns it black; where oil / grease is still presenton the surface, the acidic solution cannot react with the Zinc and thus remains brightly metallic in color. Thusthe affected areas that have not been properly degreased can be identified and clean again. The mordantsolution also etches the surface.

A "Wash Primer" should then be applied after a freshwater wash to remove the residual mordant solution. Foraged galvanized substrates the surface should be thoroughly washed to remove any soluble salts on thesurface followed by thorough degreasing of the surfaces. With both new and aged galvanizing, a light abrasionusing silica bonded paper will enhance the adhesion of the subsequent coating system applied.

Aluminium, Copper, Bross ond BronzeThe surface should be thoroughly degreased and lightly abraded using silica bonded sandpaper or light sweepblasting at reduced pressures prior to the application of paint. A suitable primer would be an etching primer orwash primer.

5. Ferrous MelolsMetal corrosion, virtually synonymous in the paint industry with rusting, is simply the tendency of a ferrousmetal to return to its natural state as an ore. lt is largely due to electrolytic reaction which takes place in thepresence of moisture and air. The application of a protective coating on the ferrous metals will provide a layerof surface coating film to retard rusting by the exclusion of water and air from the metal surface.

The exclusion of water and air by a paint film is more theoretical than factual, for all organic paint films arepermeable to moisture in some degree (an organic paint film is a chemical composition of carbon compoundsof living organisms). Film breakdown due to corrosion under the film; may take place quickly if the surface isnot properly treated and is not provided with a corrosion inhibitor.

Phosphating a metal surfaces with iron or zinc phosphate is of great value in providing adhesion for an organicfilm as well as in providing a corrosion inhibitor to lengthen the life of film. Some finishing materials prevent rustand corrosion; some are practically neutral; others actually promote the action. An effective metal protectivecoating, therefore, requires a dense material and rust-inhibitive pigments. Unlike wood surfaces, polishedsteel surface lacks the profiles required for favorable paint adhesion.

Another condition exists in the finishing of metal products. The slightest abrasion of the finished surface willcause the metal to rust. This rusting will spread under the paint film, causing premature breakdown of thesurface coating. Paint adherence to metal, therefore, must and can be improved by (1) roughening the surfacemechanically or chemically (2) depositing a film improves the bond between paint and metal. Various cleanersor methods are used to prepare a metal surface.

Alkali cleaners of a 5-10% caustic solution are commonly used to clean the surface. Thorough rinsing is almostimportance because any alkali residues left on the surface will affect the paint adheston.

Acid cleaners are frequently used to remove rust and scale. A B-10% aqueous solution of sulfuric acid or com-mercial hydrochloric acid is very effective in removing rust from a metal surface. Due to the safety and hazardsinvolved in this type of acid cleaning, it is wise to consult an expert before proceeding.

A 5% aqueous solution phosphoric acid not only removes a considerable amount of surface contamination butalso forms a very thin crystalline structure which improves paint adhesion.

Emulsion cleaners in which soaps and detergents are mixed with water are very effective means in removingoil & grease. Thorough rinsing is necessary. Abrasive blast cleaning produces a chemically clean and roughsurface which is most ideal for painting. As newly blasted surface may rusts very quickly, painting must befollowed immediately.

Wiping with thinner or solvent is quite effective as a metal cleaner, especially on small surfaces

Mechanical cleaning with a wire brush or abrasive paper is quite effective in removing rust or loose mill scale

The proper surface preparation method would be selected accordingly to the paint system to be applied andavailable facilities. Unless othenvise specified in the painting system, abrasive blast cleaning to SA 2.5 ofSIS 055900 or equivalent is always the most economical and effective surface preparation.

Surfoce Roughness (Anchor Potlern)ln connection with surface preparation, roughness is defined as the irregularities in surface texture, which arecaused by abrasive blast cleaning. Most paint system need an anchor pattern characterized by a surfaceroughness to obtain maximum adhesion.

The anchor pattern must be clearly specified seperately in specifications for surface preparation. During actualfield work, the anchor pattern can be easily and conveniently assessed by visual or tactile comparison, usingsta nda rd ized comparators.

AbrosivesThe abrasive used in blasting shall be graded steel grit, flint, silica sand, or similar, and shall be such that it willproduce a surface roughness complying to the specification and requirement as per the respective primercoating. The abrasive shall be dry, clean and free from soluble contaminants.

CleoningAfter blasting, remove all accumulated grit, sand, dust etc., by vacuum cleaning or by clean dry compressedair, leaving the surface always clean, dry and free from mill scale, rust and other foreign matter.

Surfoce Preporolion SlondordsListed below is a summary of the most commonly used standards.

Surface Preparation Specifications (SSPC-S P0)

Surface Preparation Standards for Painting Steel Surfaces. (SlS 055900)

Surface Finish of Blast Cleaned Steel for Painting. (854232)

Surface Preparation Specifications for Abrasive Blast Cleaning. (NACE)

SSPC-SP1 Solvent Cleaning Removal of loose rust, loosemill scale contaminants withsolvent, alkali emulsion orsteam.

SSPC-SP2 Hand Tool Cleaning Removal of loose rust, loosemill scale and loose paint todegree specified by power toolchipping, descaling, sanding,wire brushing and grinding.

srs 055900 B, C, D-St2 Removal of loose rust, loosemill scale and loose paint todegree specified by power toolchipping, descaling, sanding,wire brushing and grinding.

SSPC-SP3sls 055900

Power Tool CleaningB, C, D-Sr3

Removal of loose rust, loosemill scale and loose paint todegree specified by power toolchipping, descaling, sanding,wire brushing and grinding.

SSPC-SP5srs055900854232NACE

"White Metal" CleaningA, B, C, D, -Sa3 FirstQuality No.1

Removal of all visible rust millscale, paint and foreign matterby blast cleaning by usingsand, grit, shot or gamet. (Forvery corrosive atmospherewhere high coat of cleaning iswarranted.

SSPC-SP6sts055900B54232NACE

"Commercial" CleaningB, C, D, -Sa2Two-third of eachelement of Third Qualitysurface area is free ofall No.3

Blast cleaning until at leastvisible residues. (For ratherseverer conditions of exposure.)

SSPC-SP6sts055900NACE

"Brush-Off' CleaningB, C, D, -SA1No.4

Blast cleaning of all excepttightly adhered residues of millscale, rust and coatings,exposing numerous evenlydistributed flecks of underlyingmetal.

SSPC-SP8 Pickling Complete removal of rust andmill scale by acid pickling,duplex pickling or electrolyticpickling.

SSPC-SP1Os1s055900NACE

"Near White Metalblast cleaning secondquality No.2

Blast cleaning nearly to whitemetal cleanliness, until at least95% of each element of surfacearea is free af all visibleresidues. (For high humidity,chemical atmosphere, marine,or other corrosive environment.)

Ihis doto sheet supersedes oll previous issues. (LZG /02/0s/13) KCC Points Sdn. Bhd.(121967 ft