Mordants (Alum, Iron & More)

ALUM (Alum Sulfate):
A mineral mordant used to help dyes bind to fiber. It's also used in pickles! And papermaking! In use since Ancient Egyptian times and beyond. Use 10% alum for the weight of fibers to be mordanted. When dyeing cellulose, I give the fibers a tannin bath beforehand (see our wildforaged sumac). You may see a flocculate or cloudy appearance in the water: this is just the alum causing the minerals in your water to condense. Cool huh?

IRON (Ferrous Sulfate):
Historically referred to as "copperas" or "green vitriol," this food-grade powdered iron is used as a mordant for dark colors, or as an after-bath to shift and darken colors. Yellows become greens, beige goes grey or brown, and reds can take on a near purple hue. It is also used with ecoprinting to react with tannins. Using powdered iron is a great alternative to homemade rust baths when you are working with a larger quantity of fibers (such as yarn), and need to achieve a full color shift. Just use a pinch, and add more as needed to shift colors.

ALUMINUM ACETATE (For cellulose):
Used for mordanting cellulose fibers such as cotton, linen, hemp, etc. Produces a clear mordant with no patina of a tannin, so it's excellent for bright colors as shown! **This powder is very fine and should be used with care, including wearing a dust mask and gloves.**. Use 10% mordant to weight of goods. Dissolve in hot water (it will be gummy!). Add to your dyeing vessel with the hottest water your tap will produce. Submerge the fabric for 1 hour, or until you can get back to it. Rinse before dyeing. 50 grams will dye approximately 1 lb of fabric (500g).

As with many dye stuffs, make sure you practice standard safety skills with these materials: don't inhale vapors or dusts, and wear gloves as it is a possible skin irritant.

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