Dammar gum , from India and Near Asia, has been used as a varnish for oil paintings.
It is traditionally prpared by dissolving the gum in turpentine solvent.
In my research, I have found that Dammar gum (light yellow) can be dissolved ( 10-20% m/v) in oil of citrus ( -limonene) at 90 deg C in 2-3 minutes with light stirring. The cooled solution is then gravity filtered to provide a colorless varnish. Without filtration, the dried surface will have a yellow coloration.
Many oil painters are working in very limited space and the varnish, prpared this way, has a pleasant smell and turpentine fumes are avoided.
I have used a heat gun to dry the varnish ( applied to bristol paper) in minutes.
I hope oil painters will consider this healthier approach in their work!