3600 2K Urethane Primer is a two-component acrylic urethane primer surfacer formulated to be applied as a high build sanding primer, or a final non-sanding primer-sealer. 3600 offers excellent filling properties with minimal coats, fast dry, excellent adhesion, easy sanding and superior color holdout. 3600 does not shrink and can be tinted with basecoat tints.