A vocabulary of landscape — a landscape of words
1367 entries
mordant
A mordant is a substance used to fix a dye to a fiber. Most natural dyes will not bond to wool or cotton on their own and will wash straight out; a metal salt applied before, with, or after the dye forms a bridge between the two and holds the color. The mordant also changes the color, sometimes dramatically, so one dye plant can produce a whole range depending on what it is fixed with.
Etymology
The word is French, from the Latin for biting, and the image is the mordant biting into the fiber to give the dye something to grip. The same Latin root gives English morsel, a small bite, and remorse, which is something biting back at you.
Notes
Alum is the standard mordant and has been for thousands of years, and control of the alum trade was a matter of European politics for centuries. Iron darkens a color, tin brightens it, copper pushes it green.