Steve Costain replies: I like to finish parts on the lathe with a quick coat of shellac, then a wipe-on varnish (General finishes is good) and then a coat of wax.
Bruce Hamilton replies: I finish my tunings with shellac, either waxed or de-waxed. Zinsser’s Seal coat is de-waxed shellac. It is a tough and durable finish, easy to apply, dries quickly, is readily repairable and re-coats with good adhesion. The shellac is applied like French polishing of which there are many videos online.
If you wish you can apply oil like Watco to enhance the wood’s color before applying the shellac. Oiling a wood like walnut or cherry will make it darker. It enhances the grain of all woods. Let the oiled wood dry for a few days at room temperature before applying the shellac.
Watco now offers hand applied poly finishes. I haven’t used them but this may also be a material to apply to turning while the work is spinning on the lath.
Tage Frid published two books on wood working with Taunton Press in 1981. He talks about mixing shellac and oil together. He called this his 4F finish. His students named it the F4 finish translated to “Frid’s Fast Fine Finish.” His two books are excellent and are available used online.