Potassium Dichromate K2Cr2O7  Potassium dichromate has important uses in photography, it is a common inorganic chemical reagent. Gum bichromate printing Carbon print to harden gum and gelatine when exposed to ultraviolet light. Used in the bleach solution in bromoils. Handle with care: it is carcinogenic and corrosive Handle with gloves, eye protection and appropriate health and safety protection.