mordancy /mörˈdən-si/ noun

morˈdant adjective

1. Biting
2. Incisive
3. Serving to fix dyes, paints or gold-leaf

1. A corroding substance
2. Any substance that combines with and fixes a dyestuff in material that cannot be dyed directly
3. A substance used to cause paint or gold-leaf to adhere to a surface

To treat with a mordant

morˈdantly adverb