Potassium Alum (potassium aluminum sulfate)

Mordant, fiber pre-treatment.

Potassium Alum at 7-10% WOG.

Mordant for Protein Fibers

Experts differ and suggest a range of potassium alum use from 7% WOG to 15% WOG for alum sulfate on protein fibers. General consensus is about 7-12% alum sulfate for silk and wool. Too much alum will change the hand of wool and make it “sticky”.

Extract Preparation

Use potassium alum based on the dry weight of the silk or wool goods (WOG). Add mordant into pot and dissolve completely. Soak clean fiber at least l hour in warm water with a touch of soap, rinse and then add to mordant pot with enough water to cover the fiber in the pot.

For silk and wools, slowly bring pot temperature up to a simmer for one hour, then let stand without heat for at least 2 hours and up to 24 hours. Stir at least twice after the heat is removed. By 48 hours the fiber and mordant reach maximum benefit. For wools, the same simmering instructions, however, do not boil, as unintentional felting may result.
For silk and wool, rinse cooled fiber lightly in warm water to wash off the mordant liquid, squeeze gently (never wring) and proceed with dyeing, painting or surface designing. Silk and wool may be dried at this time, and stored until you are ready to dye.

It is not recommend  to mordant silk and wool together in the same mordant pot (unless you are using a blended fiber, of course). Dyeing silk and wool in the same dye pot is not recommended, as the dye uptake rates are different, and the dye will not be shared fairly by the two fibers.

Mordant Pot Economy: When mordanting regularly with the same substrate, (dedicated silk mordant pot, dedicated wool mordant pot), it is possible to ‘re-seed’ the mordant pot by using the remaining mordant solution from the previous mordanting event. Reseed the pot with 50% of the prescribed mordant on WOG of the new goods, with additional water to cover, as always. Generally, one may practice mordant pot economy for about 4-5 rounds of use before the bath becomes murky.

Pre-Mordant, pot mordant and post-mordant: the three opportunities for immersion mordanting. Generally we consider the pre-mordant to be mandatory for great results. Mordanting in the pot with the dye simultaneously has received mixed reviews, and we are not great fans of this style. The post-mordant tends to be a ‘cart before the horse approach, dipping a dyed fiber into a mordant bath after the dye process has taken place. The DyeWorks does not consider post-mordanting to stand alone as a mordanting technique.

If you are mordanting large quantities, you may keep the dry and mordanted fibers in storage until you are ready to dye. The mordant effect enhances with air curing time for wool. You may wish to mark your fabric/fiber with a code to remind you that it has been mordanted.

Mordant for Cotton and all Cellulose Fibers:

General Recipe: for cotton, rayon (all cellulose fibers). Cellulose fibers are chemically neutral, therefore the mordant process is more difficult to achieve for effective, saturated color. The recommended approach to mordant cellulose is a 3-step process based upon the procedures developed by James Liles. It is crucial to follow the steps, in their suggested order, for best results.

Weigh your fiber to establish the dry WOG (weight of the goods) before you begin this process. Pre-treat your cellulose fibers by machine washing in hot water with a moderate amount of detergent and washing soda. You may dry your fiber after this, or proceed with mordanting. Vegetable rinses (found in grocery stores) intended to remove waxes work well to clean cellulose.

Step 1: Scour

  1. Fill your pot with water, based on the following general guide: 2 quarts (2 liters) for every 1 ounce (28 grams) of fabric used. OR: 1 quart (liter) for every ounce (28 grams) of yarn to be mordanted.
  2. To this pot of water, add in 1 tsp. Synthropol for every gallon of water in the pot. Add in 2 teaspoons washing soda (soda ash) for every gallon of water in the pot. Dissolve the washing soda in boiling water before adding it to the pot.
  3. Wet your fiber for one hour. Add your fiber to the pot, bring to the boil and hold a simmering boil for 4 hours, covered. Stir occasionally.
  4. Rinse fiber in warm water, squeeze and set aside.

Step 2: Tannin Soak

  1. To a fresh pot of water, adequate to cover the fiber, add in 6% tannin, on the WOG. Dissolve the tannin in boiling water and add to the pot. Bring pot temperature up to 130 F.
  2. Add scoured fiber to pot, stir well, cover and let stand to steep for 12-24 hours at room temperature. Do not add more heat.
  3. Rinse fiber in water, squeeze and set aside.

Step 3: Alum Mordant

  1. Dissolve alum sulfate in boiling water, at 50% WOG.
  2. Dissolve washing soda in boiling water at 6% WOG.
  3. Fill fresh pot with water to cover fiber. Add alum and washing soda to this pot of water. Stir.
  4. Add scoured, tannin soaked fiber to this pot. Bring pot up to 170 F, stirring occasionally.
  5. Cover and let stand for 12-24 hours at room temperature. Do not add more heat. Stir once or twice during this time period.
  6. Remove fiber and rinse well.
  7. Let dry and air cure for 1-3 days.
  8. Wet material for one hour, and proceed with dyeing.

This process is laborious yet necessary for true success with cellulose dye projects. Once you are comfortable with this process, it will fit into your dye studio routine.

Mordant Pot Economy: When mordanting regularly with the same substrate, (dedicated silk mordant pot, dedicated wool mordant pot), it is possible to ‘re-seed’ the mordant pot by using the remaining mordant solution from the previous mordanting event. Reseed the pot with 50% of the prescribed mordant on WOG of the new goods, with additional water to cover, as always. Generally, one may practice mordant pot economy for about 4-5 rounds of use before the bath becomes murky.