Mordants are needed to set the color when using
natural dyes. Different mordants will
give different results.
Alum: (Aluminum Potassium Sulfate)
This is the most widely used mordant. Be careful not to use too much with wool, otherwise you
will get a sticky feeling that doesn't come out.
Copper: (Copper Sulfate)
This mordant is used to bring out the greens in dyes. It will also darken the dye colors, similar to using tin, but is less harsh.
*Chrome: (Potassium Dichromate)
Chrome brightens dye colors and is more commonly used with wool and
mohair than with any other fiber.
Extremely toxic. Chrome should not be inhaled
and gloves should be worn while working with chrome.
Left over mordant water should be disposed of at a
chemical waste disposal site and treated as hazardous waste.
Iron: (Ferrous Sulfate)
Dulls and darkens dye colours. Using too much will make the fiber brittle.
Glaubersalt: (Sodium Sulfate)
Used in natural dyes to level out the bath. Also use
in chemical dye.
Spectralite: (Thiourea Dioxide)
This is a reducing agent for indigo dyeing.
Tara Powder: (Caesalpinia Spinosa)
Tara Powder is a natural tannin product. It is needed
for darker colors on cotton, linen and hemp.
Tartaric Acid: A must for cochineal. This mordant
will expand the cochineal colors.
Tin: (Stannous Chloride)
Tin will give extra bright colors to reds, oranges and yellows on protein fibers.
Using too much will make wool and silk brittle. To avoid this you can add a pinch of tin
at the end of the dying time with fiber that was premordanted with alum. Tin is not commonly
used with cellulose fibers.
Is to be used with indigo powder for the saxon blue color. It
can also be used to lower the acidity of a dyebath.