Chemochromic inks for printing
Chemochromic inks are inks changing colours after contact with various chemicals.
The inks react to i.e. alcohols, esters, acetone, chlorohydrocarbons, aromatic compounds, ammonia or sodium hypochlorite (the active ingredient of bleach).
The effect of the change can be reversible or irreversible. The colour change is caused by a chemical reaction between the pigment and a defined chemical.
Chemochromic inks can be used as indicators in various industries, e.g. as an indicator of contact with gas, pH change, presence of ions, as an indicator of moisture or food spoilage.
These inks can also be used for document security printing. Any attempt at removal of the print (e.g. by using bleach) is immediately visible on the printout.