Welcome-what kind of burl??
Denatured alcohol is used as a method to reduce the time to remove moisture from a rough turned bowl. It will not help with dimension changes.Really nice find .You could soak the " cookies " in denatured alcohl in a large garbage bag for a short time . Can't remember the exact time but someone on the Turning forum could help you out. Turners do this with roughed out bowl blanks .