Recently, on an online art forum, a member posted a question regarding whether "Damar Varnish can be made with standard turps or petroleum-based turps instead of the recommended gum turps?" As the Q&A ensued, it became clear that many don't know the difference between the variety of solvents available to today's artist.
For the record, damar varnish can be made only with turpentine. You can't dissolve damar resin in mineral spirits.
Turpentine is made from the resin of certain pine trees. It's known also as spirit of turpentine, oil of turpentine, wood turpentine or gum turpentine. Only artist's quality turpentine should be used for varnish.
Mineral spirits comes from petroleum. It's also known as paint thinner or brush cleaner, and the more purified brands may be called odorless mineral spirits or OMS. Mineral spirits is sold in hardware stores under a variety of names. Artists should only use highly-refined OMS because of the interaction of impurities with pigments in less-refined types. Some brands of OMS for artists include Gamblin's Gamsol and Weber's Turpenoid.
By the way, Turpenoid Natural, which comes in a green can, should not be used for thinning oil paint. It contains a non-drying oil. It's great, however, for rinsing out brushes. Regular Turpenoid, which comes in a blue can, can be used for thinning paint.
Robert Gamblin of Gamblin Colors has some good notes on solvents here:
