u/IeatL1ttlekids

I've been reading through different varnish recipes and one of the simpler ones got colophony, linseed oil, turpentine, siccatives and gum mastic, and last one I have trouble acquiring. From what I understand it speeds up the drying process of the finish, but can you swap it out with dammar? The google ai(which I do not like to trust) says you can use sandarac and dammar, is it true? What other things you can add instead of mastic for the same function?