Learn to paint in Acrylic paints - Step by Step
Golden's latest newsletter is an eye-opener. As a direct result of their own research, they are discontinuing the use of Zinc Oxide in their oil colours. This is due to the extreme cracking and delamination noted in relatively fresh paint films (2 years and 10 years). Even dilution of Zinc White to under 2% in mixtures still produced the same degree of failure. Part of this is due to the interaction of the pigment with the fatty acids normally present in oil paints.
Similarly, they have detected a decided shift in the relative light-fastness of Hansa Yellow pigments in acrylic films. While not as dramatic as the problems with Zinc White, they have come out with two new yellow pigments that are substantially similar except their tinting strength is somewhat weaker. There are no immediate plans to discontinue the Hansa colours, but Golden will be changing the ratings from 1 to 2 for these pigments. It was noted that incorporating as little as 10% Golden Gloss Medium into the Hansa Yellows markedly improved their light fastness back to the "excellent" or #1 rating.
If you have any interest in such things, please visit the Golden website and review their newsletter. These articles are somewhat technical, but provide an insight into the quality assurance they perform on our behalf.