Home » Hardener Hardener Written by Bryan Joslin on November 1, 2023 A substance that accelerates the drying and curing of paint. Related Articles: Best Under Hood Paint For Engine BayHow To Use Paint Mixing Cups For A Better FinishWhat is the Difference Between 2K AeroSpray and 2K DuraSpray?Glossary: 2KThe Differences Between Acrylic Enamel and Urethane Auto Paints