Single stage urethane is a one-step painting process for automobiles that avoids the necessity of a clear-coat finish. The paint is durable enough to polish without altering the color tone, and using it reduces the overall refinishing time. The urethane must be mixed with a hardener and reducer before spraying and, while the ratios may vary from product to product, the typical ratio is 4 parts paint to 1 part hardener to 1 part reducer.
Apply rust conditioner to rusty areas and use a plastic putty knife to fill holes and dents with body filler. Feather the filler into the body with sandpaper.