Abstract: An aqueous primer composition useful for priming substrates such as steel, polyester reinforced with fiberglass, acrylonitrile/butadiene/styrene plastics that are used in automobile and truck bodies and can be dried at ambient temperatures comprisesA binder of an alkyd resin which is the esterification product of drying oil fatty acids, an aromatic dicarboxylic acid, an anhydride of an aromatic tricarboxylic acid and a polyhydric alcohol such as an alkyd resin of soya oil fatty acids, phthalic acid, trimellitic anhydride and trimethylol propane;Pigments in a pigment to binder ratio of about 300/100 to 10/100; typical pigments are talc, barytes, and zinc/calcium molybdate; andAbout 0.05-1.0% by weight of an anionic polyelectrolyte dispersant; andA sufficient amount of ammonia or an amine such as triethyl amine to provide a pH of about 6.5 - 8.5.