In planning out my own artwork, and the courses I teach, I decided to use Low-VOC paint. Now for you readers I will explain what that is: Volatile Organic Compounds. The chemicals within the paint. Here is a link: http://www.epa.gov/iaq/voc.html (this is the government epa site).
Unfortunately there is not a whole lot available for artists. What is available is through-the-roof priced! They are mostly designed for interior wall painting, not artwork. Color-mixing with these paints would be nearly impossible.
I could use milk paint, with a much larger palette. But, milk paints work better on rigid supports. Not real conducive to painting on canvas! Here is a color chart from the “Old Fashioned Milk Company”: http://www.milkpaint.com/color.html
Egg tempera is horribly difficult and tedious for the novice to use. Glair might be interesting. Both would spoil quickly and rotten eggs are rather nasty.
This summer I am going to be experimenting with plant and vegetable dyes, natural minerals, and also powder pigments for my own work. I will be using some animal-based and plant-based binders. I will post my results as I work through all of this experimentation.
The lazy part of me is whining about the fact that I cannot just purchase these in a handy-dandy tube form. Anyone out there tried these forms of pigments?