Well now that I know about this thread I’ll have plenty of opportunity to contribute.
So today I was making about 20 pounds of lavender goats milk soap. I use “African Violet” ultramarine to color my lavender GM soap, which I typically mix with glycerin and stir into the lye, as it tends to mix better that way. Well. Today I got clever and mixed it into the water before I added the lye. Lye stirred in, no problem, I had it in a cold water bath, went to check on it about a half hour later, and it had turned GREEN. I’ve never had this happen before. I think the heat was a factor because typically I am stirring the pigment into cold lye. I’ve used the same pigment many times with no problems.
This is how we learn, grasshopper.