The cause of yellowing of oil-based paints has been investigated by analysing drying oils simultane- ously by iodometry (to determine the degree of oxidation) and by colorimetry. It was found that yellowing of drying oils can be attributed to co-oxidation reactions of contaminants. Yellowing level is closely related to the extent of drying and appears to be unaffected by increase in temperature, the addition of driers, or linolenate content.
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