Marina13, and as such can be? because if pigment is unstable, it is connected with its chemical nature, if you change it himprirodu, it is another connection and another pigment. Not explain how you understand it? or all strontia yellow unstable, and some producer has three stars on the same pigment .... a miracle of marketing?
We looked Multi base producers, some VanDik less stable, others more, and Schminke puts all high resistance. They are highly resistant and lemon. Riddles ... most likely a new dyes, made under the usual color of concrete.
Yes, it is. I dropped into your own site Schminke
http://www.schmincke.de/produkte/oelfarben1.html?L=1
and read that their academic series of 48 color DOES NOT CONTAIN CADMIUM! although the names of solid cadmium. So it's all Synthetics!