Alum (Potassium Aluminum Sulfate)

Alum (Potassium Aluminum Sulfate)


Make your project a success with aluminum sulfate. Alum is used with some natural dyes as a mordant. Especially for Bengala dyeing on wool, it prevent felting by skipping the extra steps of rinsing and kneading in the pre-fixer process. Alum water works like pre-fixer to help the color stick to the wool fabric or yarn more easily.

Also it is a powdered presoak used to treat fabric or for marbling. It ensures that designs transfer clearly to fabric or paper surfaces. This package contains one pound of aluminum sulfate. Made in USA.

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How to Bengala-dye using alum

Ingredients: Water, Alum

Mixing alum water with Bengala mud dye helps the color go into the fabric easily. It is convenient when used to dye felting-prone materials such as wool or yarn. No need to pre-fix the fabric. You can use the mixture during the dyeing process to make it get into the fabric, which prevents felting by reducing the number of steps of the whole process.

1. Weigh the material (fabric, raw wool, yarn) you are going to dye.

2. Put tap water that is 10 times the weight of the fabric in a bucket.

3. Measure an amount of alum water in order for the water in the bucket to contain 3 % alum water, then pour into the bucket and mix.

4. Pour the amount of dye you like and mix well.

5. Soak the material in the dye bath and knead it lightly.

6. The dye solution becomes clear as you keep dyeing. If you want deeper color, repeat the steps from 3 to 5.

7. Squeeze the dyed fabric lightly and then wrap it in a towel to remove excess water.

8. Dry it well and the whole process is finished.


  • Alum water makes it easy to dye by promoting ionization. Excessive use causes the pigments to adhere to each other preventing good dyeing results. Please use the proper amount and enjoy dyeing.

  • Excessive Kneading causes felting of the material

  • Superwash wool, which has been processed to remove the scales on the wool fiber to prevent felting and tangling, dyes better with pre-fixer. The smoother fiber of superwash wool is actually harder for Bengala dyes to stick to, and as it won’t felt, we recommend pre-fixer.