U of S | Mailing List Archive | alt-photo-process-l | mould over gum

mould over gum

This is not a new technique, but a problem submitted me by a friend.
She told me that some of her gum bichromates have developed small white dots, and asks for something able to kill the mould and its spores but not the color.
I am thinking to salicylic or ascorbic acid (or their salts) instead of the old more poisonous mercuric chloride, or to some commercial agricultural products. Have you any better solution?