What effects (yellowing) can forced drying at around 50-80 °C produce in alkyd resins based on tall oil/wood oil?
Yellowing, accompanied by darkening, is observed mainly in alkyd resins containing linolenic acid. It is assumed that quinone-like compounds are formed, which can decompose when exposed to light. In this respect there is, therefore, a major difference as far as force dried tall oil/wood oil alkyds are concerned, where yellowing probably indicates the start of decomposition.
As far as the pigments are concerned, the relatively slight temperature increase in the case of forced drying compared with pure heat curing is unlikely to have any effect upon the pigment. The largely inert chrome yellow is likely to be stable under these circumstances.
Yellowing of Alkyd Resins
Blog, Updated at: 5:27 PM
