How to Mordant

Our How To guides are intended to make the dye process easy, from scouring your fibers to dyeing with an assortment of dyes. You can find other How To guides here.

What is Mordanting?

Mordanting is the most important process of preparing fibers to accept color. Using a mordant helps to ensure the most durable and long-lasting colors. With the exception of indigo (as a vat dye, it does not require a mordant), this is not an optional step. However, there are many different mordants you can use. Deciding which mordant to use comes down to the types of fibers you want to dye and how much time or energy you wish to spend. The table below breaks down the different mordants that we sell and the advantages and disadvantages of each one.

(Check out our Q & A: Round Up of Mordanting + Scouring 101 here.)

What kind of fibers are you dyeing?

Different mordants can perform better or worse on different kinds of fibers. We divide fibers into two categories. The first category is cellulose fibers. This category includes all plant-based fibers, such as cotton, linen, and bamboo. The second is protein or animal fibers. This category encompasses any fiber that comes from an animal, including wool, cashmere, alpaca, and silk. If you are dyeing a blend of protein and cellulose fibers (such as wool/hemp, silk//bamboo, or silk/cotton), use mordants that can dye both types, as seen below. As a general rule, synthetic fibers and fabrics such as nylon and polyester will not dye well with natural dyes.

For those of you who are just starting to learn about natural dyeing, we recommend aluminum sulfate (for protein fibers such as wool and silk), aluminum potassium sulfate (for protein fibers), and aluminum triformate (for either cellulose fibers such as cotton and linen or protein fibers). These three mordants are easy to use and deliver wonderful results.

Which mordant should you use?

For basic mordanting, refer to this table. Once you are comfortable with these techniques, you can experiment with different mordants on different fibers and compare and contrast the results to find out what you prefer.

MordantFiber typesAdvantagesDisadvantagesDetailed Instructions
Aluminum Acetate with wheat bran or with calcium carbonate afterbathCellulose fibersProduces bright colors

Does not require heat or energy
Multi-step process

Aluminum acetate is a very fine powder and can be irritating to work with.
See more.
Aluminum Potassium SulfateProtein fibersEasy to use

Produces bright, clear colors
Recommended to use heat/energySee more.
Aluminum SulfateProtein fibersEasy to use

Quick process
Recommended to use heat/energySee more.
Aluminum TriformateCellulose and protein fibersEasy to use

Does not require heat/energy
Longer processSee more.
SymplocosCellulose and protein fibersBio-based from dried leaves rather than mineral-basedLonger process

Requires multiple steps for cellulose fibers
See more.
Tannin and Aluminum SulfateCellulose fibersMost lightfast mordant for cellulose fibersTannin can alter dye colors slightly as it has a color of its own.See more.