# Reduction of triphenylmethane dyes in ink

Right now I'm trying to explain why the ink from an ink pen turns colourless in water.

I know that the pH is responsible as it breaks apart the conjugated system of double bonds. I'm just not sure on which part, to $$\ce{OH-}$$ comes into play (example: Water blue).

My suggestion would be that $$\ce{OH-}$$ can be reversible added to double bond in the center forming two phenyl rings and one ring with 2 double bonds (which will rearrange into a phenyl ring with the double bond from the following amide-group) with a $$\ce{C-OH}$$ in between.

Under acetic conditions, the $$\ce{OH-}$$ is eliminated.

Is that correct and does anyone know a mechanism, explanation etc. for that reaction somewhere on the Internet?