If you are looking for a less expensive alternative for mordanting, consider Aluminum Sulfate. This mordant contains the same active ingredient (alum) with a different refining process as Aluminum Potassium Sulfate. It has more irregular-shaped granules (called kibble) that produce near identical results. It is a wonderful mordanting material for protein fibers such as silk and wool.
Use between 10-20% alum on the weight of fiber. 250 grams will mordant about 2500 grams (5.5 lbs) at 10%.
We love that these dye baths may be used either hot or cold, and may also be re-used with the addition of more alum. This allows the dyer to use less energy and conserve more water. Check out our blog post entitled Using Less to Get More for more information about reusing alum baths. Also check out our How To Mordant instructions for detailed information on preparing your fibers for natural dyeing.
WHAT IS MORDANTING?
Mordanting is the most important process of preparing fibers to accept color. This is not an optional step but there are many mordant variations. Using a mordant helps to ensure the most durable and long-lasting colors. Below we highlight some of the more common mordant methods used.
The technique is simple (for animal fibers): measure the mordant, dissolve in water, and add to a dye pot or bucket or tub filled with water. Simmer the fibers for a period of time, then remove and proceed to the dye bath. Although many substances have been used in the past for mordanting, we prefer aluminum potassium sulfate or aluminum sulfate as a mordant for animal or protein fibers.
We calculate all mordants from a percentage of the weight of fiber. “Weight of fiber” refers to the dry weight of the yarn or fabric to be mordanted. We use it primarily when weighing mordants and dyes and allows you to quickly and easily calculate how much to measure. Therefore, a kitchen scale is handy to determine the weight of yarns or fabrics.