A New Check Security Feature: Thermochromic Ink

One of the newest check security features being utilized today is a logo or mark printed on a check using color-changing ink. This allows anyone to verify the authenticity of a document quickly and easily. By rubbing your finger over the mark, the document can be authenticated immediately, and can be repeated over and over again as the check is passed from person to person. But just how does thermochromic ink work? The chemistry of the ink and use of it both in document security and in other applications are discussed.