Burned samples from what? A Stradivarius? How can that be?
Maybe they have some ruined samples that can be sacrificed... that’s all I can think.
I’d bet it makes little difference what they were finished with, and more difference what the ultimate dimensions (including the thicknesses) are. Sometimes violin makers find that the unfinished instrument sounds better in testing, but they can’t leave them that way as the wood would deteriorate.