Gentlemen I'm curious. How deep does the wood get burnt? Is it deep enough to sand afterwards? Once burnt does it have to be left alone or finished? Thanks.
Pete, I believe the depth of the burn line depends on the burner. A microwave transformer will burn hotter, flame up, and scorch more around the burn, and burn deeper main lines. The shorter the burn time will help with depth not becoming too deep. The neon sign transformer and the Conestoga Works unit burn with less intensity. Like wise with an oil furnace transformer.
After burning, the piece is usually cleaned under running water with a nylon brush to remove the char and soot. After the piece is dry, light sanding can be done to settle down the raised grain.
At that point, any Finish may be applied as usual. An oil finish such as Tung oil finish or Danish Oil Finish or a spray lacquer can be used. With the burnt lines, CA or friction polishes are probably not the best choices.
If one sands the blank, raises the grain and resands before the burning, there will be less raised grain to deal with later.