re: Lets Talk "oil finishes"

Here is some information on “varnishes,” which would include poly finishes.

http://tcpermaculture.com/site/2014/08/04/tapping-the-pine-tree-plant-resins-and-their-uses/

“Varnish – This is a protective “finish” or application for wood and other materials. Varnish is usually transparent or mostly transparent. It goes on wet and dries hard. It can have various levels of sheen (high gloss, glossy, semi-gloss, satin, etc.). Traditional varnishes contain an oil, a resin, and a solvent. The oils, also known as drying oils, harden after long exposure to oxygen. Examples of drying oils are linseed oil, poppy seed oil, tung oil, and walnut oil. Resins have been discussed at length above, and varnish resins include amber, copal, balsam, copaiba, elemi, mastic, rosin, and sandarac. The most common solvent, by far, is turpentine.”