sltopcoat.htm

We highly recommend the use of our new 94U-1000 primer for brush application instead of the old U-1000. It brushes easier and forms a heavier film.

Photo of boat being brushed at dockside with Sterling

Here, two painters handle the topsides gloss application at dockside. One rolls a thin film on the surface while the other tips with a brush, first vertically, then horizontally.

Always use Sterling Tac Rags for final dust removal just before topcoat application. Lightly wipe, do not scrub, changing rag surface regularly to keep clean. Do not use solvents with tac rags as they are only for final dust removal.

For brush application, mix two parts STERLING color base with one part U-2964 Brushing Catalyst and always add required accelerator to base before mixing with catalyst. See USE OF ACCELERATOR. Click here.

Mix components thoroughly in a clean, non-waxed bucket and allow the mixture to pre-react thereafter for approximately 45-60 minutes. This is important to induce the chemical crosslinking process before the material is spread into a thin film and a much better finish and cure will occur. Do not add thinner when the components are initially mixed. Just before application, thin to proper brushing consistency with U-2965 Brushing Thinner at the rate of about 25% on the average. More or less reducer may be indicated depending upon the color used and prevailing weather conditions. To preserve 490 g/l VOC use no more than about 10-15% reducer. Diminished flow will result. Thinner can be added as job progresses, whenever brush starts to pull.

Do not apply in direct, hot sunlight, particularly with dark colors. Application in early morning helps greatly in warmer weather.

When weather is extremely cold, U-2965 may not evaporate quickly enough from the film to produce a tack-free surface before sags appear. Furthermore, if surface of film becomes tack-free before the thinner has evaporated, loss of gloss may occur, within an hour or two following application. This is due to the brushing reducer breaking the polymer down on its way out of the film particularly when accelerator is used. This effect most often occurs below decks where air circulation is at a minimum or on shady surfaces in cold, humid weather.

These conditions can be
corrected by adding a small amount of faster reducer to the mixture.

A few capsfull of U-1014, U-1385 or C-8761 will speed evaporation, to correct the problem. If it persists, a heat lamp will help dry the surface quicker, just after surface flows to a good gloss.

Photo of power boat being brushed in marina

After the mixture has pre-reacted and has been thinned, it is always wise to apply a small amount of the material to a clean, nonporous surface as a trial before proceeding to coat a large area. The back of one of the thinner cans is an ideal test surface. If brush marks do not flow by the time the surface has become tack free, more thinning will be necessary. If sags or runs occur on test surface within the time it takes the surface to become tack free, the material has been applied in too great a coating thickness, possibly it has been thinned too much or it may not be tacking dry quickly enough. Consider these factors before re-applying. Wipe off test film with thinner and try again until ideal combination has been attained.

Always strain catalyzed, thinned mixture into carefully-cleaned, uncontaminated paint bucket, with extra fine paper cone filters. Thinner may be added to mixture any time during the application process whenever surface film feels too sticky and brush begins to pull with difficulty. Handle this exactly as if working with an enamel for if mixture is under-thinned, surface texture will not flow and if over-thinned, coverage will be poor and sags will soon be apparent.

STERLING gloss must be brushed in reasonably thin coats, hence a good quality and very clean Chinese bristle brush (we favor the Corona "Europa" model) should be used to minimize brush marks and allow the material to flow into an even coat. On large surfaces, two brushes should be used and they may be alternated when bristles become sticky. Simply immerse the brush bristles in C-8761, squeegee a few times or comb with a wire brush and that unit will then be ready when the alternate becomes sticky.

Low nap (1/8") foam rollers available from your dealer or DETCO, compatible with the STERLING system, permit quick and even distribution of gloss on larger surfaces. Immediately following application by roller in a workable area, the film must be quickly brushed into a smooth film with a wet brush, horizontally and vertically, in order to remove the roller stipple, small bubbles and overlap tracks from the roller. The roller is a quick vehicle for basic application into an even film but it should always be followed by brush tipping. The larger the surface, the greater the area covered by initial rolling, as the wet line should extend from the top to bottom of the area being coated, then moved horizontally along the working area.

Try to avoid brushing STERLING gloss in direct, hot sunlight, particularly when using darker colors. On an extremely warm day it may be easier to work on the shady side of the boat. In cooler weather, by contrast, it may be more appropriate to work on the sunny side, to facilitate good material flow and relatively quick tack time. Some colors brush with greater ease than others. The dark greens and blues are among the most difficult to apply. Thus, if a large surface is to be painted with one of these colors, spray application is recommended or consult DETCO.

Good painting practices should be followed when applying STERLING by roller/brush. Apply material to a small area (approximately 1-2 square feet) without overloading brush or roller. Push material into a thin film and draw back into the wet line with bristle tips until the film is smooth and even. Do not brush film too long. It is necessary only for the coating to be placed on the substrate in a thin, even film. STERLING will then take care of itself by stretching into a bright gloss.

Usually cross tipping an area two or three times, in opposing directions, vertically and horizontally, is ample to achieve good flow if the material is mixed at proper consistency. Final tipping is often done vertically by many applicators and helps prevent sags. Some brush marks will be evident after tipping 2-3 times, however, the coating has an uncanny ability to stretch out as it begins to dry as one will notice as the job progresses. Proper brushing consistency should be maintained at all times by adding thinner and stirring thoroughly as necessary.

Although many of the colors look well after just one coat, a second application the next day is indicated for proper coverage. This may be applied within 36 hours without sanding or with only minor abrasion so that on reapplication, the applicator can differentiate the new film from the prior one. If a second coat is applied more than 36 hours after the first, unless temperatures are very cold, thorough sanding to eliminate all glossy areas is advised, for proper adhesion. Do not apply more than one coat per day.

Clean brushes thoroughly, immediately after using, with STERLING C-8761 Brush Cleaner. Brushing Reducer will not work! Brushes should be very well rinsed, wire brushed or combed to remove all traces of cured material and squeezed numerous times after dipping in solvent. Allow the brush to soak 15-20 minutes after the first cleaning, before final squeezing. Usually a brush will not be clean enough to use for topcoat application after two days’ usage because of cured material in the heel of the brush. The unit can then be relegated to primer application thereafter.

Practical coverage for brush application is between 200 and 400 square feet per catalyzed gallon depending upon coating thickness.

IMPORTANT: When curing conditions in outdoor exposures will remain around or below 70°F, when fog or dew are expected and certainly in the winter months along the West Coast when painting is done in the open, STERLING gloss coatings will usually require acceleration to produce a chemical cure before dew or fog fallout causes damage to the film.

Chemical cure is prolonged by cooler temperatures and if moisture lands on the surface before the material has adequately cross-linked, the surface may lose its gloss. This is known as blushing, flatting-out or hazing. If severe, the surface will have to be re-prepared and new gloss applied. If moderate, i.e. a very slight hazing, it may be corrected when the surface has reached maximum hardness, if localized, by using a very fine rubbing compound such as 3M Finesse-It II.

It is best to complete gloss application early in the day, to prevent blushing, and by the use of U-2900 Accelerator. On warm days, it is advisable to use only enough accelerator to create a tack-free surface within 15-30 minutes or so and this may require from a few drops to one-eighth ounce or so per mixed quart. Increase quantity of accelerator as temperatures drop below 70°F during application and curing period. A maximum of one-half ounce of U-2900 accelerator per mixed quart may be used under extremely cold conditions for spraying. Do not use this much except in extreme conditions. This will reduce the 12 hour work life of the mixture, however it will decrease the tack-free time in cooler weather, speeding up the film cure sufficiently so that it may be applied outdoors with less risk of blushing. The more accelerator added, the faster the film will dry. Remember, if it sets too quickly, it may not flow and brush marks or spray stipple may be evident upon drying. Always use accelerator sparingly at first until its action becomes familiar.

For application by spray, combine one part STERLING U-Series color base with one part STERLING U-1001C SPRAY CATALYST. When needed, always add U-2900 accelerator to color base before mixing with catalyst. Read “Use of Accelerator” on previous page. After catalyzing, allow mixture to pre-react for 30 minutes and then thin to appropriate spray viscosity.

U-1275 reducer may be used above 80°-85°F, and with darker colors. U-1014 reducer is best for temperatures of 70°-80°F, U-1385 reducer from 50°-70°F and, in extremely cold weather below 50°F, C-8761 may be used. The latter is a very fast evaporating thinner, however, and is best blended with U-1385 in cold weather as a trial, before being used by itself. If the solvent flashes or evaporates too quickly, spray stipple will not flow and the surface will not demonstrate the wet look, characterized by STERLING gloss when correctly applied.

Caution: Take care in enclosed spaces around boats or planes, to insure adequate air exchange when temperatures range above 80-90ºF. When ventilation is limited in high temperature and humidity conditions, small blisters (solvent pop) can ruin surfaces. Excessive film thickness or too many passes can also complicate this.

Always use STERLING TAC RAGS to remove dust just before topcoat application. Lightly wipe surface, do not scrub and change rag surface constantly to keep clean. Do not use solvent with tac rags. They are only for final dust removal.

The catalyzed gloss must be thinned 25% to one-third with most colors to produce best results and with some (black and other dark hues), even greater reduction may be indicated so that the film lays down as intended. Reduction always varies with colors and air temperatures but nearly always, STERLING gloss requires a minimum of 25% reduction.

If a viscosity cup is used, the #2 Zahn or the plastic Dupont cups provide a good measure of proper viscosity when the cups evacuate in 17-18 seconds.

Thinner should be added to the mixture as subsequent paint pots are filled from the original mixing bucket in order to restore proper viscosity. As time passes during an application project, the catalyzed mixture continues to thicken and, with solvent evaporation more thickening occurs, so if reducer is not added as the job progresses, consistent flow will be unlikely.

Spray equipment should always be thoroughly cleaned before topcoat application. Always cycle a few ounces of spray reducer through the gun to make sure all fluid passages are uncontaminated, that the spray fan is even and the gun is functioning properly. Siphon cups should have fluid tip orifices of about .060 inches to .070 inches, adequate for all STERLING gloss coatings and finish primers. Pressure cup fluid tips should be very small, .040 inches to .050 inches, to promote slower application, better atomization and a better quality finish. Check with DETCO or your distributor for specific fluid tip, needle and air cap combinations for your gun.

Always strain catalyzed, thinned mixture into paint pot with extra fine paper cone filters.

Gloss must be applied in two passes over the surface during one application, and with some of the transparent colors even three might be indicated. Generally, however, STERLING’s polyester urethane system is so high in solids that the colors cover excellently with only two passes over the work surface.

The first coat should have just enough material to produce wetness and good flow. It should not be “fogged” on or stipple results and good flow will not occur. A good mirror image should be evident on the first pass, within just a few minutes, but the surface may not be thoroughly hidden, particularly with some of the more transparent colors.

If the tack coat is applied too heavily, substantial drying time will have to be allowed to prevent sags when wet coat is applied especially in cold weather. If tack coat is too light, there will be evident stipple or dry spray, which will not flow out as the second coat is applied. It is, therefore, important that the first pass be applied with as much care as the second, for good surface uniformity.

Best results are achieved by siphon cup or pressure pot, the latter generally being much easier when painting large surfaces such as boats, planes and trucks. Airless application is for the highly experienced and only for very large jobs such as commercial jet aircraft or architectural surfaces. The household airless applicators, incidentally, do not work satisfactorily. STERLING is successfully applied by many of the new air-assisted airless, electrostatic and HVLP guns but these tools, typically, do not produce the high surface gloss delivered by conventional equipment and they generally take more practice to use successfully.

Set up the gun for minimal material flow, making it unnecessary to move the spray gun across the work too rapidly. Much better quality can be achieved by painting slowly for STERLING does not dry as fast as many automobile lacquers and enamels. When using a siphon cup, material flow should be set so that at a convenient speed across the work area, the surface is just wet enough to flash a good gloss within a few minutes. When using a pressure pot, use only enough fluid pressure to produce good gloss at a convenient speed over the work area, generally no more than 5-6 psi on the pot regulator gauge.

STERLING is so resin-rich that it requires high line air pressure to atomize the material for good flow. Generally 55-60 psi is adequate at the gun. Bear in mind that substantial pressure reductions occur the longer the air hose, hence increased pressure at the compressor may be necessary to produce 55-60 psi at the gun.

The tack coat may develop interim dry spots as it begins setting up. If there are too many dry areas it suggests more fluid flow or slower gun movement across the work surface in order to provide slightly greater surface wetness. Any dry spot or stippled area noted as the tack coat is being applied should be loaded with slightly more material so that it will stretch into a glossy film immediately. This is generally done by pulling the gun further away from the work and “dusting” the surface with a few light passes, watching carefully for the gloss to stretch. One can then resume coating from the wet line with no fear of dry spray.

After applying the tack coat, allow the surface to become dry to the touch which may take 30 minutes to an hour or more, depending upon ambient temperature and humidity, as well as the amount of accelerator used and the applicator’s choice of reducer.

The wet coat must not be applied until the tack coat has stretched into a smooth film and has dried to the touch, or an orange peel surface will result. The wet coat should flow within a few minutes into a high gloss and if an orange peel texture is noted, excess coating thickness due to under-thinning is likely the cause. It may also be that the tack coat has not sufficiently dried. Air pressure should be checked and increased as another possibility.

If the film is drying too rapidly, orange peel can result, hence a slower evaporating thinner might be indicated. As temperatures change during the day, during the course of a large job outdoors, it may be necessary to move to a slower evaporating reducer for the second pass. Consider also reducing the amount of accelerator.

Remember STERLING is a high solids, very high quality linear polyurethane and it does not have to be applied in heavy coating thickness to achieve the desired results. Generally a dry film of 1.5-3 mils, derived from a wet film of 3-5 mils is more than sufficient to provide all of the resistive properties of which the material is capable.

For application by spray, combine one part STERLING color base with one part STERLING (U-1001C) Spray Catalyst. Always add accelerator to color base before mixing with catalyst. After catalyzing, allow mixture to pre-react for 30 minutes and then thin to appropriate spray viscosity. See USE OF ACCELERATOR. Click here.

Sterling U-1015 Midnight Blue being sprayed

U-1014 Midnight Blue is sprayed on a 63' power boat. Using a DeVilbiss gun with a 2-quart pressure pot, the painter applies the second or wet coat over the tack coat, applied about 45 minutes before.

The surface must be dry to light pressure and should stretch into a clear and reflective gloss before the final coat.

This new-age product is the result of extensive research and development and represents state-of-the-art in low VOC, high solids, premium quality urethane coatings. 94 U-color base is mixed 2:1 with 94 U-5000 catalyst and allowed to pre-react for 30 minutes before thinning,

Un-thinned, this system can be applied at 419 grams per liter VOC and at approximately 20% reduction, it may be used within a 490 grams per liter VOC limit. The main difference between this product and standard STERLING gloss is a somewhat slower film cure time, reduced pot life (about 4 hours at 70°F) and a notably heavier film build with each coat, because of the higher solids make-up. Coverage is far better.

Otherwise, this product has already proved itself as a long term performer, demonstrating gloss retention in tropical exposures, even better than its predecessor, with the added benefit of easier repairability.

This new-age product is the result of extensive research and development and represents state-of-the-art in low VOC, high solids, premium quality urethane coatings. Unthinned, this system can be applied at 419 grams per liter VOC and at approximately 20% reduction, it may be used within a 490 grams per liter VOC limit. The main difference between this product and standard STERLING gloss is a somewhat slower film cure time, reduced pot life (about 4 hours at 70°F) and a notably heavier film build with each coat, because of the higher solids make-up. Coverage is far better.

MIXING INSTRUCTIONS: For application by spray, mix two parts STERLING color base (94-U-color #) to one part STERLING 94U-5000 spray catalyst, always adding the U-2900 accelerator to the color base before mixing with catalyst. After catalyzing, allow mixture to pre-react, about 30 minutes, and then thin to appropriate spray viscosity. See USE OF ACCELERATOR FOR LOW VOC SPRAY. Click here.

THINNING: Un-reduced STERLING LOW VOC is applied at 419 grams/liter. A somewhat orange peeled surface may result, however, without thinning.

In order to stay below a VOC limit of 490 grams per liter, the mixture may be thinned up to a maximum of approximately 20% using U-1385 in temperatures below 65-70°F, U-1014 from about 70-80°F and 80°F or above, U-1275. Thin just before application.

APPLICATION: After priming with the appropriate STERLING primer and sanding surface to a clean 220 grit profile, wash with detergent and water and thoroughly rinse the day before or, if impossible, thoroughly blow surface dry with clean air or wipe with clean rags, followed by a light wipe with C-8762 Surface Prep.

Normal application viscosity for 490 grams/liter compliance will be approximately 18-19 seconds on a # 2 Zahn cup.

As subsequent paint pots are filled from the original mixing bucket, thinner should be added in small quantities, to restore proper viscosity for, as time passes during an application project, the catalyzed mixture continues to thicken because of solvent evaporation. If reducer, therefore, is not added as the job progresses, consistent flow will be unlikely.

Always strain catalyzed, thinned mixture into paint pot with fine paper cone filters.

Gloss must be applied in two passes over the surface during one application. STERLING LOW VOC is so high in solids that most colors cover well with only two passes.

The first coat should have just enough material to produce wetness, continuity and a good flow a few minutes behind the area sprayed. It should not be "fogged" on or stipple will result and a good flow will not occur nor can it be covered by the second pass. A good mirror image should be evident on the first pass within a few minutes although the surface may not be thoroughly hidden, particularly with some of the more transparent colors.

If the tack coat is applied too heavily, substantial drying time will have to be allowed to prevent sags when wet coat is applied, particularly in cold weather. If the tack coat is too light, there will be stipple or dry spray that will not flow as further material is applied. The first coat should be applied with as much care as the second, for best results.

After applying the first coat, allow the surface to become dry to the touch, which, with STERLING LOW VOC, may take 30-60 minutes depending on the ambient temperature, humidity, the amount of accelerator used and the applicator's choice of thinner. Do not apply the wet coat until the tack coat has stretched into a smooth film and has dried firmly to the touch or an orange peel surface may result. The wet coat should flow within a few minutes into a high gloss and if an orange peel texture is noted, excess coating thickness due to poor atomization is likely the cause. It may also be that the tack coat has not sufficiently dried.

If the film dries on the surface too rapidly, consider using a slower thinner or reduction of accelerator. If it sets up too slowly, add more accelerator for second pass.

The first pass should be approximately 2-3 mils wet and the second should be applied similarly, drying to a dry film of approximately 2-3 mils.

STERLING 68A Series topcoats are two-component high solids coatings for any weather-exposed surface where ultra high gloss, chemical resistance and faster dry are desired.

This new product exhibits the same mirror-like finish as the conventional U-Series polyester urethane system but, a softer surface, it is easier to buff and repair. Application defects such as dust, sags and localized texture may be corrected without costly repainting and, when the coating shows signs of age, it can be restored with non-abrasive polishes, without harm to the finish.

Caution: Do not mix additives other than 68A4899 Accelerator and recommended thinners with acrylic 68A Series topcoats without distributor consultation.

STERLING 68A acrylics have demonstrated application ease, excellent performance and enviable gloss retention in tropical environments on yachts, fish boats and in the industrial field.

SURFACE PREPARATION: Any cured STERLING primer surface is appropriate for 68A topcoat application. Thoroughly sand before topcoating with 280-320 grit. Blow sanding dust from surface with clean, filtered, high-pressure air or wash with water the day before topcoating. Just prior to topcoat application, wipe surface using clean white rag lightly saturated with STERLING C-8762 Surface Prep solution. Use STERLING tac rags for final dust removal.

MIXING: Thoroughly mix two parts STERLING 68A Color Base with one part STERLING 68A5001 Catalyst. Add STERLING 68A4899 accelerator if indicated (see below). Mix in Reducer to a volume of 40% to 50% of catalyzed mixture. The components are much higher in solids than conventional STERLING, hence the greater percentage of requisite thinner than with conventional systems. No pre-reaction or induction time is required.

ACCELERATION: CAUTION: Do not use STERLING U-2900 ACCELERATOR. To speed up dry-to-tape time, use up to 1 liquid oz. of STERLING 68A4899 Accelerator per gallon of color base used. Experimental use of Accelerator is advised on small areas before coating large surfaces, as shorter tack-free and reduced overspray melt in times will result.

THINNER SELECTION: When temperatures during application will exceed 75°F, STERLING U-1275 Reducer will provide ample open time on large topside surfaces to prevent dry spray. For smaller applications, however, use STERLING U-1014 Reducer or STERLING U-1385 Reducer depending on temperature levels. When application temperature is below 75ºF, STERLING U-1275 Reducer may work best on large areas, but there’s a greater possibility for sags due to its slow evaporation rate. STERLING U-1014 Reducer or STERLING U-1385 Reducer may work best in cooler climes.

APPLICATION: Applicator may use the same equipment customarily employed to spray conventional STERLING topcoats. If anything, increase line air pressure above usual levels. Greater pressure is needed to break up the higher solids material. Coverage is excellent, requiring only two passes over the work surface.

Apply first coat in an even, glossy film, with just enough material to provide full surface continuity, (wet film thickness between 1.5 to 2.5 mils). It is important to paint slowly and deliberately, to avoid dry spots, even on first coat. Allow surface to dry until completely tack-free. Due to the products’ high solids characteristics ample re-coat time between the first and second coats is imperative, in order to allow maximum flow, and solvent release, reducing the possibility of excessive orange-peel. This can take as long as 30 to 45 minutes depending on ambient temperature.

The second coat should be applied in the same manner, but a bit heavier (wet film thickness between 2.5 to 3.5 mils). Take care to avoid dry spots. Retouching such areas is different than with conventional STERLING topcoats, for a dusting over the dry spot with the spray gun can create a dry spray halo and the possibility of sags in the retouched area. It is important that the applicator watch the pattern just behind the gun to assure uninterrupted wet surface continuity to avoid the need for retouching.

Last modified: November 12, 2004 Website Design: D. E. Templin & Associates, Inc. (800)-845-0023