m: receipts reacting to alcohol-based hand sanitizers

Question

why do receipts react to hand sanitizer?

So I’ve noticed that the receipts I receive at stores turn dark grey whenever they’re exposed to hand sanitizer. Is this because the ink they’re typically printed with is alcohol-based and the paper is designed to chemically react?

In: Chemistry

Answer 1

Thermal paper is made of a dye suspended in a matrix of paper the dye is exposed by a laser in the printer. The alcohol is essentially dissolving the matrix and exposing the dye.