What is an Anti-Soiling Treatment?
An anti-soiling treatment is a clear coating applied to a banknote before or after printing, intended to extend the lifetime of the banknote by making it more resistant to dirt, oils, moisture and physical wear. An anti-soiling treatment may also be called a varnish, and is sometimes abbreviated as “AST.” The treatment may also be designed to improve ink adhesion to the substrate.
By improving resistance of the note to dirt, oils, moisture and physical wear, the circulating lifetime of the note can be extended, before it becomes unsatisfactory and must be withdrawn from circulation and destroyed. Cleanliness and physical damage affect not only a note’s reliability and ease-of-use in person-to-person transactions, but also how well the note may be handled by bill validators and cash handling machines, such as ATMs and vending machines.