slprime.htm

These thick, high solids materials are used to fill very rough surfaces such as coarse ground or sandblasted metal, bare wood, new fiberglass and fairing compound. They will cover deep surface defects which would take a finish primer several or more coats to fill. More difficult to sand, they are best over coated with finish primer before top coating.

U-4747 yellow strontium chromate epoxy high build primer is the new generation, LOW VOC corrosion-preventative barrier primer with the advantage of high solids, heavy film build, and less shrinkage than finish primers.

It is used as a moisture-proof, anti-corrosive barrier coating over chemically converted aluminum or blasted steel and is most effectively used with pressure feed conventional, HVLP equipment or airless spray, building to a 10-15 mil dry film coating thickness in two to three heavy passes. Allow interim drying time between coats to avoid solvent entrapment, waiting to recoat until surfaces are dry and firm to finger pressure. U-4747 is used by the most prestigious steel and aluminum builders and is widely acclaimed as the most corrosion-resistant primer available. Thin as needed with U-1289. Coverage will be about 100 sq. ft. per mixed gallon.

Mix U-4747 1:1 with U-4748 catalyst and allow 30 minutes pre-reaction time before application. Just before applying, thin up to 25% or so for application by spray, less by roller, with U-1289. Use C-8761 reducer in temperatures below 60-65°F. VOC is 295 g/L, unthinned and 320 g/L reduced about 12%. Pot life is about 4 hours.

U-4747 is most effectively used with pressure feed, HVLP or airless spray, building to a dry film thickness close to 20 mils if applied in several heavy passes. Allow interim drying time to avoid solvent entrapment, so that surfaces are firm and dry before recoating. Three or four hours' wait may be required in temperatures less than 70°F.

U-4749 can be used as a guide coat over the chromate primer Use in lieu of the final coat of U-4747. When the U-4749 is taken down over high spots, sanding can be halted at the first sign of the yellow U-4747 showing through beneath. This prevents compromising the chromate-on-metal interface. Coverage will be about 100 sq. ft. per gallon.

U-4749 LOW VOC HIGH BUILD EPOXY PRIMER, catalyzed 1:1 with U-4748, is the new generation high build, with relatively fast curing characteristics, excellent build and easier sanding qualities than many high builds. It has become the standard high build surfacer for bare wood, rough glass surfaces, for use over sanded fairing compound, and composites. Pre-react 30 minutes and for spray, thin up to 25% or so with U-1289. Below 60-65 F use C-8761. Little thinning is needed for brush/roller application. It has gained wide acceptance in mega-yacht construction facilities and boat yards for high build finishing, owing to its nominal shrinkage, relatively quick cure in cooler temperatures and its fine pigment makeup. Coverage averages about 100 sq. ft. per mixed gallon.

VOC is 264 g/L, unreduced and 336 g/L thinned about 12%. Where higher limits are permissible, it may be thinned for smoother flow, up to 25% or more. Pot life is about 4 hours.

Caution: Where temperatures after application are expected to be below 65-70°F, allow 4-5 days cure time before over coating or applying fairing compound, to assure full release of solvents and complete chemical cure.

Surfaces primed with LOW VOC high build primers and left sun-exposed, should be top coated within 24 hours after sanding or primed with U-1000 or 94U-1000 primer. This is important as exposure to the elements for extended periods before top coating could result in topcoat to primer adhesion failure. As an advantage, however, extended exposure of primed surfaces to the sun will cause darkening which, when sanded back to original color shortly before top coating, will illustrate a completely flat, ready-to-paint surface.

U-1000 Primer, a white, relatively quick-drying polyurethane is mixed with U-1000C Catalyst in a 2:1 ratio and may be applied immediately, with no pre-reaction time. It is the standard marine and transportation primer for gel-coat, existing finishes, plastics, composites and for application over high build epoxy primers, having excellent adhesive and sanding characteristics. Pot life is 6 hours. It is one of the faster curing finish primers in the industry.

U-1000 is used as an intermediate/finish primer on aircraft and as a finish industrial and marine primer. It may be brushed with a good quality natural, bristle brush or rolled with foam roller sleeves available from your dealer or DETCO, when applied on larger surfaces. Use only rollers specified for STERLING as other brands may come apart rather quickly from solvent contact. Even the special rollers will begin to deteriorate after 30 minutes or so, thus for a large job, lots of them should be purchased.

When priming larger surfaces such as hulls and wide cabin expanses, heavily saturate roller sleeve and apply a thick film from upper to lower margin, stroking surface lightly with a wet brush just once across roller pattern to level roller texture and settle bubbles. Cross-brushing primer will create deep brush marks as surface will dry quite quickly. Brush is used only to level surface when material is applied by roller. Several coats are advised. Just allow film to dry 30 minutes to an hour, until firm, before recoating. Coverage averages about 150-200 sq. ft. per mixed gallon.

When sprayed, U-1000 is best applied with siphon, pressure feed or new HVLP equipment, the latter greatly reducing over spray and waste. Preferably in two passes, allowing tack-free time between coats, U-1000 is applied by thinning 20% or so for fine-sanded surfaces or unreduced for deeper profiles. U-1000 may be coated with gloss after overnight drying, without additional surface preparation for an industrial finish, while best results are obtained after overnight cure and a thorough sanding to a 220 grit profile. For automotive refinishing, especially with dark colors, finish sanding to 280/320 is frequently employed, to reduce the possibility of sanding scratch print-through. Exercise caution in going to finer grit, however, particularly on surfaces adjoining varnished bright work where masking tape will be applied frequently, for the finer the sanding profile, the greater the possibility that masking tape can lift the topcoat film.

U-1000 has a good combination of properties and characteristics but, in areas of heightened pollution control, or for brushing, 94-U1000 is preferred.

94U-1000 Low VOC (BEST FOR BRUSHING). This newer primer, a white, relatively quick drying polyurethane similar to its predecessor, U-1000, is higher in solids, covers better, requires fewer coats and shrinks less. In heavier films and cooler weather, it may take somewhat longer to cure to good sandability.

Mix primer base 2:1 with 94U-1000C Catalyst and apply immediately as no pre-reaction time is needed. Pot life is short, about 2 hours. As with U-1000, a heavier film build may be produced by allowing freshly-primed surface to become firm, whereafter subsequent coats may be applied for desired coverage. Primer may be applied full strength for maximum build or may be thinned for more even spreading, whether by brush or spray. Recoat without sanding, up to 24 hours. Coverage is about 150-200 sq. ft. per mixed gallon.

Use U-2965 thinner, only if needed, for brush application and for spray, either U-1014 in warmer weather or U-1385 in cool temperatures. To achieve 420g/l, thin up to 5%, and up to 25-30%, if desired, where limits are higher. VOC is 406 g/l, unthinned.

U-1201 yellow, strontium chromate epoxy primer is mixed 1:1 with U-1202 catalyst and should pre-react one hour before thinning and application. This meets Mil Spec No. Mil-P23377D, for aviation and transportation and is an excellent anti-corrosion coating for use over chemically-treated aluminum and properly prepared steel. For years an aircraft standard, U-1201 is also used as a finish primer for aluminum components and marine accessories such as spars, antenna masts and trim.

Best sprayed by siphon, pressure feed or new HVLP spray equipment, U-1201 is thinned 20-50%, depending upon surface profile to be covered. Due to its low solids makeup, U-1201 is not designed for heavy plated aluminum hulls nor immersed surfaces since it cannot be applied in adequate film thickness to create a sufficient immersion, moisture barrier. Pot life is 6-8 hours. Coverage is about 200-250 sq. ft. per mixed gallon.

U-1201 demonstrates excellent adhesion, anti-corrosive action and may be recoated when dry, up to 24 hours after application, without sanding.

For aluminum sailboat spars, U-1201 may be brushed where spraying is impractical and it is best applied unthinned over chemically-treated surfaces, using a good quality natural bristle brush. Because of its low solids configuration, when brushed, it must be recoated several times over the course of a few hours to achieve adequate film thickness. Allow surface to become firm before recoating. Last coat should dry overnight, whereafter an intermediate application of brushed U-1000 primer may be employed without sanding, to serve as a sanding surfacer prior to top coating. Sanding the U-1000 will permit the removal of surface texture and brush marks without compromising the anti-corrosive chromate primer film.

Caution: If U-1201 will be over coated the same day with U-1000 or 94U-1000 as an intermediate primer or with topcoat, assure film has adequately cured to avoid solvent entrapment and blistering. Virtually no fingerprint should occur with pressure on the film and as a final test, it should powder sand at least slightly with 220 grit as a final check to confirm safe recoat.

U-1201G LOW VOC yellow, strontium chromate epoxy primer is mixed 2:1 with U-1202G catalyst and should pre-react 30 minutes before thinning and application. VOC is 336 g/L unthinned. More thinning with U-1289, where limits are higher, will permit a smoother sprayed film.

This product is compliant as a finish aviation and marine finish chromate primer where its predecessor, U-1201, would be ruled out by regulators. It meets new Mil Spec No. Mil-P23377G, for aviation and transportation, demonstrating excellent anti-corrosion protection over chemically-treated aluminum and steel. A new aircraft standard, U-1201G may also be used as a finish primer on aluminum marine components such as spars.

BRUSHING: A higher solids formulation than its predecessor, U-1201G is more easily applicable by brush, builds to a heavier film with fewer coats and has better brushing characteristics. Recoat as soon as film is firm to touch and does not fingerprint.

Caution: If U-1201G will be over coated the same day with U-1000 as an intermediate primer or with topcoat, assure film has adequately cured to avoid solvent entrapment and blistering. Virtually no fingerprint should occur with pressure on the film and as a final test, it should powder sand at least slightly with 220 grit as a final check to confirm safe recoat.

M-3225 yellow vinyl-butyrate chromate wash primer is catalyzed 1:1 with M-3226 phosphoric acid reducer, thinned about 25% with U-1014 and applied in very minimal thickness (2-5 wet mils) as an aluminum and steel pretreatment primer where chemical conversion is impractical, for marine, aircraft and transportation functions. M-3225 is an aircraft standard and, because of its low surface hiding characteristics, is best overcoated with U-1201 or U-1201G, 94U-1000 or U-1000 primer prior to topcoating. This primer is often used to coat interior aluminum surfaces on boats where acid etching and Alodine application are impractical, followed, often, by the application of high build primer or urethane topcoat. It is important that this primer is not applied in heavy coating thickness or adhesion will be compromised. It is applied in a transparent film, one pass and may not be satisfactorily brushed.

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