Most of my scrollwork gets finished with shellac. Depending on the wood, I may apply a coat of boiled linseed oil first, to pop the grain, and then spray on the shellac as a topcoat. For decorative scrolled items, it's become my "go-to" finish. Most of the scrollwork I do doesn't require a heavy and durable finish like a piece of furniture would.
I spray it with a gravity fed, HVLP spray gun. The reason I like it is that it dries so fast and cleans up so easily. For fretwork, the fast drying provides the benefit of being able to hit the piece from multiple angles, to get in all the inside cuts. If applied lightly, I have no problems with too much build up from the multiple coats and I can get complete coverage and be done in no time. It The fumes dissipate pretty quickly, although if I'm doing a lot of heavy spraying, I always try to do it outside. Denatured alcohol is flammable in high enough concentrations, but as someone else said, I think it's a little friendlier than lacquer thinner.
For other woodworking items, such as furniture, I will use whatever the project dictates, based on the type of wood and the function of the piece. I mostly prefer an oil varnish instead of a polyurethane. Sometimes I mix it with boiled linseed oil and mineral spirits to make my own version of a Danish oil. I've recently used a waterborne, oil modified polyurethane, which did a pretty good job. Waterborne finishes are fast becoming the standard as VOC regulations are making it harder & harder for manufactures to ship solvent based finishes and meet EPA standards.
