I remember a cute little paragraph in one of MacIntosh's books (I'm nearly sure) about a story in a London pub near the Gun Quarter ,about some old Gunsmith cch'ing an action by wrapping it in newspaper, well drenched in his "filtered ale" & then stuffing it in the middle of a good hot coal fire?...he didn't report how it turned out..:)...maybe he could vary the colours be changing brand beer??
It is fascinating how it works..colours are so nice.
franc