My position is this: we shouldn't allow questions on every finish that can possibly be applied to wood.
Obviously every conventional finishing option from stain/dye to wax to oil to varnish to lacquer (and all combos) is a yes, ditto unusual things like chemical treatments (e.g. light exposure, alkalis, iron + vinegar) and soap finish and liming. And obviously basic painting we have to include. It's the extremely specialised and/or complex paint options that I'm thinking we should firmly limit.
Here's why. We would, in the fullness of time, have to cover queries on:
- automotive paint
- faux painting — fake marble/granite etc., metals — in both water and oil media, and in mixed media
- decorative painting, in both water and oil media
- decorative lacquer
I think there's just no way we should try to tackle all of those in addition to all of the established finish options and their possible combinations. These kinds of queries are best answered in a specialist venue dealing with that type of product, or one that commonly deals with a style of painting.
Leaving the door open to this sort of thing and taking it to a logical conclusion, down the line a questioner could legitimately expect to be able to ask about Russian icon painting here... after all, they are painted on wood.