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 (6) Vinyl Paint Viscosity Reduction. Reduce vinyl paint viscosity by warming cans in a steam box
located at the job site. Temperatures shall be maintained below 48.3C (110F).
(7) Spray Gun Adjustments. For each application or new paint shipment, the spraying conditions may
differ, requiring spray adjustments. Adjust the spray gun to wide fan position and the paint fluid valve to
1/2 the fully open position. Adjust the atomizing air on the gun to 60 pounds and the paint fluid pressure
to 30 pounds and sample the spray pattern. If the spray pattern is not suitable, and no further adjustment
or combination of adjustments of fan width and paint fluid valve will correct the pattern, increase the paint
fluid pressure in increments of 10 pounds, up to 60 pounds. If the spray pattern is still not suitable, the
vinyl paints need to be thinned (paragraph (5) above).
(8) Adjust the spray gun pressure to obtain a uniform fan with proper atomization. A spray pattern
that produces too dry a spray will result in a powdery surface with a considerable deposit of spray dust on
it. To correct the dry spray, reduce the air pressure and increase the paint pressure. A fan pattern created
by too wet a spray may result in a film that is splotchy or that sags. To correct the excessively wet spray,
reduce the paint pressure and increase the air pressure. Spray pattern should be kept wet and the film
continuous as the area is covered. If the fan narrows down or the paint starts to spit out of the gun, the
nozzle should be removed and cleaned.
(9) Vinyl Spray Coating Techniques. Vinyl paint shall be applied with continuous parallel strokes
overlapping the preceding stroke by at least 2 inches. The painter should not pause at the end of the
stroke, because paint will pile up at the laps, resulting in an uneven appearance and sagging. The correct
gun-to-surface distance should be maintained wherever practical and should not exceed 16 inches. A
spray coat consists of the maximum amount of paint that can be applied at one time (in one or more
passes) without sagging.
(10) Three-Pass Cross Technique. To produce uniform films of proper thickness, a three-pass cross
technique has been found particularly suitable for vinyl primer application to large areas. Cover an area
with horizontally-oriented spray gun passes, moving the gun at a speed that will keep the spray pattern
wet and the film continuous as the area is covered. Next, cross the same area with vertical passes of the
gun. Lastly, horizontally re-cross the area. These three passes of the gun are considered one spray coat.
(11) Confined Area Techniques. In confined areas, such as crown frames and other welded structural
members, it is usually not practical to cross-stroke each spray pass. In such areas, the spray passes
should be made back and forth in the same direction and the painter should reduce the middle of the
spray pattern to fit the structural member. To cover tight corners and weld areas, the pattern should be
reduced to a small oval.
a. Description. Polyurethane coatings are a two-component coatings system that consists of part A and
part B. Once they are mixed together and applied as a paint film, the coating cures to a hard film by
chemical conversion.
b. Coating Hazards.
(1) Once cured, polyurethane coatings present no special health hazards but do present special
problems during mixing, application, and curing because of the possibility of free isocyanate vapors
being liberated. These isocyanate vapors can cause irritation of the skin, eyes, and respiratory tract.
Isocyanate vapors can cause severe allergic reaction in sensitized individuals and may produce asthma-
type symptoms.
(2). The material safety data sheet shall be reviewed prior to using this product.
c. Surface preparation. Surface must be clean, dry, and in sound condition. Remove all oil, dust,
grease, dirt, loose rust, and other foreign material to ensure adequate adhesion. For best performance
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