Quote Originally Posted by Photo Engineer View Post

Erythrosine is the better known of the two for having activity as a sensitizing dye for emulsions. The wedge spectrograms of Green sensitive Azo type paper was done with Erythrosine. It is a common food coloring and is an active ingredient in Merthiolate. It is easily purchased at a rather low price. My last batch came fro www.kyantec.com

Interesting, I know these substances as colouring dyes for microscopy. I never realized they had a function as sensitizing dyes. I love these parallels.