UV-550 Urethane Varnish


Clear, high-gloss, exterior and interior. The most durable varnish available.

A tough, light-fast, non-chalking, weather-, chemical-, and solvent-resistant two-part urethane varnish formulated especially for aircraft and marine wood surfaces which will be exposed to severe environmental conditions.


SURFACE PREPARATION: The surface must be clean, dry, free of wax, dirt, oil and grease. Old surfaces should be dry sanded to remove any loose varnish and paint scale. Use C-2210 Paint Surface Cleaner to remove grease and oil from new wood surfaces and old paint and varnish surfaces.

MIXING PROCEDURE: Mix exactly 1 part U-865 catalyst with 2 parts UV-550 base component. Ratio must be accurate for best characteristics. Stir thoroughly and allow 20 minutes induction time before application. Avoid shaking which causes bubbles in thick solution. Thinning eliminates bubbles. Filter thru a 60x48 mesh or finer paint strainer cone.

THINNING FOR BRUSH APPLICATION - NEW WOOD: After the two components are mixed, reduce the first brush coat 25% with toluol for good surface penetration. Second and optional third coats may be brushed unthinned at 2 to 3 hour intervals, or applied with a spray gun at 15 to 20 minute intervals.

THINNING FOR SPRAY GUN APPLICATION: Reduce the two mixed components to spray gun viscosity by adding 25% toluol (toluene) (19 to 21 seconds with a #2 Zahn viscosity cup). Three spray coats are recommended at 15 to 20 minute intervals.

RETARDER: UR-826 retarder may be added at 1 oz to 1 gal varnish for each 2° of temperature above 77°F. to delay surface drying and provide smooth flow-out in hot weather or eliminate blushing in very humid hot weather.

APPLICATION PROCEDURE: Urethane varnish may be applied with any spray equipment rated for lacquer or enamel. Flooding spray or brush coats will cause crawling and cratering over old finishes or dry first coats on new wood. Recommended dry coat thickness 1 to 1.5 mils. Contamination from oil base coatings leaching from old pressure pot hoses or contamination from unclean or soluble plastic or plastic lined containers used for mixing or measuring will cause crawling. Spray gun head should be dismantled to remove residue from previous coatings before applying urethane varnish. Application in less than 55°F or over 90°F. or relative humidity over 80% not recommended.


One gallon urethane varnish base component catalyzed and reduced 25% will cover approximately 600 sq ft with one coat.


The sooner urethane varnish is applied after the induction period the better the durability. Maximum pot life is five hours at 77°F. Discard materials when viscosity increases or becomes stringy when tested between the fingers. Do not add reducer to extend pot life after thickening occurs.


Use toluol or MEK for final flush cleaning before the varnish starts to polymerize in the equipment.


Dry to handle 30 to 90 minutes, depending on coating thickness. Full cure to develop solvent and chemical resistance is 7 days at 77°F. Lower ambient temperatures require a proportionally longer period. Fully cured varnish will not be lifted by adhesives, fabric coatings, enamel, or lacquer top coats.


Varnish coats aged more than 2 days should be dry scuff-sanded with fine sandpaper or Scotch-Brite pads to break the gloss surface and provide tooth adhesion. Wipe the scuffed surface with C-2210 Paint Surface Cleaner using new, clean rags or paper towels to thoroughly remove the sanding residue.


Guaranteed shelf life, unopened, in protected storage at room temperature is four years from date of manufacture. Avoid long-range storage above 100°F. Not affected by freezing.


Each component is sold separately, or packaged in a kit. Recommended unit ratios: 1 qt UV-550 base component, 1 pt U-865 catalyst and 1 qt toluol.