[Brenda Ellis]

In my day job, there are MSDS's (Material Safety Data Sheets) available on every chemical (even some wood) we use. I'm sure that you can find the same info on any medium for painting. If it isn't readily available, one could probably contact the maker and request one. I think it is law that they have to have this info available. Of course, this info does not tell you what will happen to the product a hundred years from now. However, as much as I love painting, I value my own longevity over the longevity of anything I produce.

As far as what will last, what will yellow, what will darken, what will crack, I am taking the safe route and using the "less is more" approach to mediums. If I were really concerned about getting the most accurate information I could about this, I suppose I would go talk to a Preservationist or Painting Restorer working for a Museum. Short of doing that, I've been watching and listening around here and I've chosen who to listen to and whose opinions to trust.

I had never heard of "oiling out" until I found this forum. I'm going to try it, ala the Michele Rushworth method. (I don't like to be bothered with mixing my paint with medium, anyway.)