I was wondering if anyone has ever engraved wood that already has a finish on it.
By finish, I mean a nominally clear finish such as polyurethane or tung oil or varnish, etc.
One finish I have been trying for outdoor use is to dilute activated acrylic casting resin with acetone
and then brush on for deep penetration of the acrylic into the wood.
Since PMMA, e.g. polymethylmethacrylate, AKA plexiglas, is a good laser cutting material,
wood that has been hardened in such a way may be a good candidate for laser etching.