1.3.1 General
Since the mechanisms of lipid autoxidation are fairly well understood,[7, 34] in the
last decade the most significant advancements in the understanding of alkyd paint drying
come from studies concerning the dry film structure of dried oils and fatty acids and the
mechanisms of the cross-link formation.
A general review of earlier work regarding all aspects of the polymerisation of
drying oils was given by Wexler,[40] and several recent reviews are available covering
fatty acid autoxidation.[7, 41] The Paint Research Association has published a report
regarding the drying of linoleic-based coatings,[42] and also a recent review is available
about the yellowing (discoloration over time) of dried oil films, studied with the model
compound methyl linolenate.[43] Yellowing is caused by over-oxidation of the coating and
is a general problem for alkyd coatings. The yellowing process will not be discussed.