Alum Mordant Solution for Tannin-Treated Plant Fiber

An alum mordant solution can be used on tannin-treated plant fiber before, after or during the dye process to create a brighter color.

Dyed Plant Fibers

For a quicker, more energy-efficient method of dyeing and mordanting, you can extract the dye and then add the mordant to the dye bath before adding your fiber.

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Home dyeing can be a gamble if you are new to the idea, but even if you are experienced in the art, knowing the different reactions given by plant based fibers and animal fibers can be crucial to proper dye absorption. Using The Handbook of Natural Plant Dyes (Timber Press, 2010) Sasha Duerr walks you through using mordants and natural dyes in perfect harmony. Get brighter results with the alum mordant solution featured in this excerpt.

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Alum Mordant Solution

After processing your plant fiber with a tannin bath before dyeing, you may want to use alum as an additional mordant to make your color even brighter. When you have rinsed the fiber of tannin, you can apply an alum premordant once, or twice for even brighter results from your dye. Wear gloves when putting your hands in the alum solution. You can save the leftover alum mordant for later use in a sealed, labeled jar. You can also use iron as an additional mordant after using tannin on your fiber, which will make your dye color darker.

4 ounces (113 g) plant fiber
20 percent (4 teaspoons) alum per fiber weight
6 percent (1 1/2 teaspoons) washing soda per fiber weight

Soak fiber in water for at least 1 hour, or overnight.

After mordanting the fiber in tannin solution and rinsing, hang it to drip while you make the alum mordant solution.

Place the alum and the washing soda into a stainless steel pot half full of water, and stir well to dissolve.

Add more water to the pot, enough to cover the fiber you will be treating, and then add the wet, tannin-treated fiber to the pot.

Heat the alum solution to the simmering point, 180 degrees Fahrenheit (82 degrees Celsius). Turn off the heat and let the fiber steep for 4 to 8 hours, making sure to stir occasionally so the fiber absorbs the mordant evenly.

Once the fiber has set (achieved maximum effect from the alum mordant), remove the fiber and gently squeeze the mordant solution back into the pot. Wash with a pH-neutral soap, rinse thoroughly, and hang to dry.

Dyeing and Mordanting Together

For a quicker, more energy-efficient method of dyeing and mordanting, you can extract the dye and then add the mordant to the dye bath before adding your fiber. Use the dye recipe of your choice from this book. This method of mordanting and dyeing together is called the all-in-one method.

Wet the fiber and let it soak for at least 1 hour.

Per the dye recipe instructions, extract the dye from the plant material, and strain the plant material from the dye bath. Let the dye bath cool down.

If you are working with a cold-water dye bath, place the appropriate amount of mordant into a cup, add some hot water, and stir to dissolve.

If you are working with a hot-water dye bath, place the measured mordant directly into the extracted color in the dye pot and stir well.

If you are working with a cold dye bath per the recipe, put the fiber in the dye bath and let it steep for several hours until the desired shade is reached.

If you are working with a hot dye bath process per the recipe, add the fiber to the dye pot, bring the bath up to a simmer, 180 degrees Fahrenheit (82 degrees Celsius), and simmer for 20 to 30 minutes or until the desired shade has been reached.

Remove the fiber from the dye pot. Wash it gently in lukewarm water with a pH-neutral liquid soap, and rinse well until the water runs clear. Hang to dry.

Use mordants and aftermordants for your home dyeing projects. Read Using Mordants With Natural Plant Dyes for more recipes and tips from Sasha Duerr.


This excerpt has been reprinted with permission from The Handbook of Natural Plant Dyes: Personalize Your Craft With Organic Colors From Acorns, Blackberries, Coffee and Other Everyday Ingredients, published by Timber Press, 2010.