I'm aware of the difference between shellac and varnish, although technically, shellac is also a varnish. In the 1800's, resins such as shellac, lacquer, copal and some others that were solvent in alcohol were called spirit varnishes. Resins that were combined with oil and thinned with petroleum or turpentine were called oil varnishes. Over time, terminology changed. Just like today, polyurethane is a varnish, but who calls it varnish?
Yes, varnish should last a while, but that doesn't mean it will. 20 years ago I bought a can of varnish, within one year I opened it to finish a table top, and had the same experience as Tamid, it refused to cure. With the exception of lacquer, it never hurts to test your finish before you use it, poor
batches do slip out and some are adversely affected by time.
Tim
