I sometimes teach woodworking to people and I like to babble at them about what I think is the most important tool, especially when the subject is guitar making and the result has to be very good. The tool is light. In 1858, using just light, Léon Foucault could measure the surface of a polished telescope mirror with an accuracy of about a millionth of an inch. It’s a powerful tool.
Good shop lighting of course, plenty of it, and of a color that’s natural and diffused so it doesn’t cast obvious shadows. I like a mix of halogen and fluorescent.
For carving, or flattening surfaces, a strong point source is great. Sunlight is best. Here’s afternoon sunlight showing high and low spots and the smoothness of the curve on a neck.
If you’re older than about 5, magnifying goggles are useful too.
Burnishing wood is so overlooked, I’m wondering if I made it up. There’s no article about it on Wikipedia, so it doesn’t exist, right? Even a search for ‘burnishing wood’ brings up only a few page related to the process I’m talking about, and a bunch of hogwash about oils and creams, as if I was searching for wart remedies. Burnishing (according to Webster) is
Definition 2. Excellent. To rub a material with a tool. I’ll skip right to it then. On a guitar fret board, particularly where the species is porous or compressible (i.e. soft), and especially where the play may be (ahem) vigorous, the luthier may burnish the surface before (and possibly after) fretting, in order to compact and smooth the surface and to make it wear longer.
I use a flat piece of stainless steel about 1″ x 4″, it has smooth, rounded edges (it’s actually the handle of a folding knife that lives on my bench). Some people use a rounded burnisher – the pressure is more concentrated this way, but it’s easy to make a dent if your strokes aren’t perfectly smooth or the wood has an uneven density. I use a lot of pressure.
Here’s a one piece neck where the material is suitable for both neck and fingerboard (it’s Tigerwood, aka Gonçalo Alves), but this wood is a little bit porous, and after some playing it’s going to wear and also collect greasy finger muck. Burnishing the playing surface closes the pores a bit, so the muck won’t get stuck in there as deep, and it compresses and smooths the surface, making it easier to clean and a bit longer wearing.
I sometimes will burnish an Indian Rosewood fingerboard for the same reasons, if it feels a little soft.
Ask a violin bow maker (an Archetier to be more precise) how they finish that tiny, incredibly stiff and resilient stick. They won’t tell you, not because it’s a mysterious secret, more likely because it’s kind of tedious and boring unless you happen to be consumed and possessed by the art, which I believe an Archetier must be. It’s burnished.