I got mine from a vet supply. Here is a link to an art supply house. I'll defer to the others on describing what it adds to the finish.

https://www.dickblick.com/products/senne...kRoCkm8QAvD_BwE

Here's what the website says it adds for artists:
Add to oil paints, mediums and varnishes for an exquisite jewel-like quality and tough, enamel-like surface.

Derived from European larch trees, this resin has the consistency of honey and is offered in its pure, undiluted state. Dilute with 20% turpentine and use sparingly to a 5% maximum of the total paint mixture.

Last edited by Woodreaux; 04/01/20 11:30 AM.
Jim