Rockhound attention

http://able2know.org/reply/post-6307922

Boy Nat, that's really a good q. I presently fix/polish a rock using spar urethane. However there are a half-dozen or other clear spray substances

Exposed to the sun some remain clear and shiny; but there's at least one such coating that gets dull and brown; so we need some input from the experts! Meanwhile I can only suggest Googling to a rockhound site


So; any rockhounds around