This blog post will walk you through the process of mordanting cellulose fabrics. This is a two step process of first mordanting with tannin and then with alum. The fabric that I naturally dye is used to make quilts that I hope will last generations. For the most lasting, even and colorfast results it’s best to diligently follow through with all these steps—from scouring to mordanting to dyeing and rinsing. Natural dyeing is an art and alchemy that takes years of practice and experimenting and note-taking, so don’t worry if your colors aren’t what you hoped for in the beginning. If you stick with it and practice you’ll get better over time. Enjoy the process, learn from each mishap and take lots of notes. Experimentation and note taking are your most valuable tools.

So lets talk mordants. A mordant is a metallic salt that bonds natural dye to fabric. Without mordant the fabric will not readily accept the dye. There are some specific dyes that fabric will accept without a mordant but I nearly always mordant first with tannin and then with alum because I don’t want to take the chance of my quilts fading.

Now lets back up a little. Prior to alum, cellulose fabrics require a tannin bath. Tannin gives cellulose fibers the ability to more readily accept a mordant. So many steps, I know!

If your goal is to dye light colors choose a light or clear tannin like oak galls, gallo or myrobalan. If you’re wanting to achieve dark colors choose a dark tannin like tannic acid, cutch, walnut or chestnut. Tannins can be used as a tool in building colors.

Tannin Mordant

A good starting point with tannin is 8% WOF. As an example, one pound of fabric is 454 grams, and 8% of 454 grams is 36 grams. If you desire to create a dark color increase the tannin amount up tp 20% WOF.

tannin recipe

1) Fill a large dye pot or plastic bucket with 120f water. Hot tap water is sufficient.

2) Add the required tannin to the bucket stirring well.

3) Place your wetted out scoured fabric in the tannin bath and stir it for a few minutes. Keep the fabric entirely submerged and steep 8- 24 hours.

4) Remove the fabric, rinse once gently and proceed to mordanting with alum.

Aluminum potassium sulfate mordant

The quantity of alum mordant—just like tannin amounts—varies depending on the dye you’re working with. Again a very generic amount to use is 10% WOF but it really depends on the dye you’re working with. If you buy dye from a dye supply store they often provide instructions and recommended amounts.

Aluminum potassium sulfate recipe

1) Fill a 5 gallon bucket with hot water around 120F.

2) Measure out the alum to 10% WOF and add it to the bucket stirring well. Add 2% WOF soda ash to neutralize the PH. As the PH neutralizes bubbles will occur.

3) Add your wet tannin treated fabric to the bucket. Keep entirely submerged for 8-24 hours.

4) Remove fabric, wring out and rinse in cold water once. Keep wet and proceed to dyeing or hang to dry and store for later use.

Alright! Now most of the boring steps are out of the way. In the next post we get to dye! You could use something foraged locally or order a specific dye from a supply store. Here are some suggestions for foraging:

Leaves from trees such as alder, birch, hawthorn, ash, walnut, apple, cherry, plum, peach, pear, apricot, oak, willow, elm, elderberry leaves or fruit, juniper branches, pomegranate skins or whole fruits, marigold tops and flowers, tansy plant tops and/or flowers, either red or yellow onion skins, black walnut husks, and avocado pits or skins or both together.

If you’re gathering leaves you’ll need enough fresh leaves to fill the dye pot you’re using. It requires a lot of dye material for a strong color. If you don’t want a strong color then gather enough to fill your dye pot about half full of dyestuffs. If you’ve purchased a dye the supplier will offer suggested WOF percentages.

I’ll have the next post ready for you soon! If you have any questions please leave them in the comment section below so everyone can see the answers. Happy mordanting!