No toxins or solvents allowed. This includes turpentine, turpenoid, mineral spirits, and odorless mineral spirits (OMS) such as Gamsol, spray fixatives (glues) and varnishes. One of your instructors, Kara, is very sensitive to fumes so she's going to make no exceptions to this rule. If you aren't sure, check your labels or give us a call to research your product for you at (208) 932-0893. You might be surprised to find your "natural" product is in fact toxic.
Find more information at M. Graham, http://mgraham.com/solvent-free-painting/ and at Gamblin, https://www.gamblincolors.com/studio-safety/studio-safety-create-without-compromise/