Oxidative polymerization of drying oil-based polymers is the most common mechanism of film formation. During the initial period of drying, the pigment is in a highly oxidizing environment due to the presence of free radicals, hydro-peroxides and activated catalysts. This environment becomes more severe with force-dried finishes that may be baked at elevated temperatures. The pigment should be inert to any of these reactions and should not exhibit a change of shade or crystal form.
Resistance to oxidative degradation
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