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).

BLUE VITRIOL (Copper Sulfate):
Used to modify colors and make blues with logwood. Leaves a sky blue or teal color to plain white wools, perfect for light blues without indigo! Use only on silk and wool. Dissolve a teaspoon in a reusable container and add fabric continuously until no blue remains. Do not empty into wild water streams, or use near infants or pets.

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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