 Several cobalt compounds are used in chemical reactions as oxidation catalysts . Cobalt acetate is used for the conversion of xylene to terephthalic acid , the precursor to the bulk polymer polyethylene terephthalate . Typical catalysts are the cobalt carboxylates ( known as cobalt soaps ) . They are also used in paints , varnishes , and inks as " drying agents " through the oxidation of drying oils . The same carboxylates are used to improve the adhesion between steel and rubber in steel @-@ belted radial tires . 
