Mastic

A resin from the pistachio tree and is from the Mediterranean areas of southern Europe. In painting, it is used to the making of varnishes. It adds in paint manipulation and gives a glossy finish but will bloom, darken and yellow so is inferior to most other varnishes. It was used in the nineteenth century in a mixture called Meglip, but the paintings in which it was used were subject to defects. Not to be used as a medium