[tommygunz]

does anyone know of a chemical that will change color when it comes in contact with the oils from a human touch. ie...will react and change color to a hand print on a glass table.
it needs to be safe enough to handle with bare skin and compatible with water and weak ammonia.
This is a tall order i know but i asked other forums and everyone sent me here. you must have the brightest people. thanks for you help.
julian

[curiouscat]

What's the application?

[Arkcon]

I don't know off-hand what the oils in human skin are made of, but its probably a diverse mixture, that differs from person to person and other factors.  However, skin oil likely doesn't react with any safe reagents.  Otherwise, we'd never have any of that reagent around, it would be so widely contaminated.

[Arkcon]

For example, the most unique component of human skin oil (called sebum) is sapienic acid (cute name -- named after our species name) http://en.wikipedia.org/wiki/Sapienic_acid  That unsaturation would decolorize bromine or iodine solutions, as an example, but it wouldn't be unique to that chemical, and those reactions are hardly safe.