Using Mordants With Natural Plant Dyes

To ensure natural plant dyes remain colorfast, sometimes using mordants is a requirement.

| December 2013

Fabric being dyed in bowls

Plant-based fibers, such as cotton, linen, and hemp, often benefit from premordanting with tannin and alum to achieve successful results.

Photo by Fotolia/nongpoo

Home dyeing can be a gamble if you are new to the idea, but even if you are experienced in the art, knowing the reaction difference between animal fibers and plant based 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. In this excerpt you will learn the basic uses of mordants and find links to several other mordant recipes featured in Duerr's book.

Using Mordants

A mordant is a fixative that allows dye molecules to bind to fiber. From the Latin word mordere, meaning to bite, a mordant is a chemical compound that can brighten a dye color, darken it, or make it colorfast. Using a mordant in the correct quantity and with the appropriate fiber can coax out a plant dye’s full color spectrum and can extend lightfastness.

When do I need to use a mordant?
A mordant can be helpful and necessary depending on the dye and fiber combination you choose. Generally, animal fibers such as silk and wool are easier for the beginning dyer to experiment with as they are able to bond more readily with most plant dyes and take less time to mordant properly. Plant-based fibers, such as cotton, linen, and hemp, often benefit from premordanting with tannin and alum to achieve successful results. Some dyes in this book, such as Japanese maple and sour grass, were chosen for their easy compatibility with plant-based fibers even without a separate mordant, as the plant dye itself already contains tannins or other natural binders which act as built-in mordants. Please pay special attention to the recommended combinations of dye, mordant (or not), and fiber as you try the recipes featured in this excerpt.

Not all plant dyes need mordants to achieve good color. Some plants dyes already contain qualities that will bind color to fiber without any additives. Not using a mordant allows you more direct contact with the natural dye colors, which can be a simple, fascinating process, and can eliminate an extra step in the dyeing process, saving time, water, and energy. The key to successful results when you skip the use of a mordant relates to the plant materials you choose to make dye from, the fiber you want to dye, and the length of time it takes for the dye to set on the fiber.

My work with natural dyes at the Edible Schoolyard led me to explore plant dyes that could work without mordants, since they are as true to their original sources as possible and do not have additives potentially harmful to children. There are many nontoxic fruits, vegetables, roots, barks, and berries that contain dye compounds that, with the right fiber, will adhere directly to the fiber without mordanting, and these are the ones I use when working with young students.

Traditionally, many mordants have been solutions of dissolved metal oxides. But mordants from plant sources such as oak galls or acorns can work just as well on fibers. Choosing your mordant wisely is one way that you can create a more sustainable dyeing practice. In the 1970s, when many of my textile and natural dye mentors were working with natural color, metal mordants were used without proper protection. Many metal mordants, such as copper, tin, and chrome, are suggested in old natural dye books, as well as in recent ones. We now know that these metal mordants are toxic and should be avoided for the dyer’s health as well as for the health of others. Many dyers now work only with alum and iron as metal mordants, since those are considered the safest to work with when used correctly.

8/3/2016 3:34:00 AM

Natural dyes are often preferred by artist because it does not pose any threat to the environment. While this is true, people needs to be informed that using natural dye requires the use of mordant, which is a chemical that helps the dye stick to fabric, and it can be toxic. Based on Keycolour, mordants like aluminum, copper, iron and chrome can have harmful effects, that is why it is essential to use gloves when handling mordants. In addition, in order to dye a wide variety of color and large volume of textile, using natural dye requires vast resources, and a considerable amount of mordant as well, prolonged exposure to mordant may pose health risk to the dyer. So you might consider using eco-friendly textile dyes that are synthetic. Although not all natural dyes may require the use of mordant so it is a matter of personal choice, regardless which type of dye and mordant you use, both will need to use resources and will have an effect one way or another.

12/31/2013 7:30:58 PM

Informative, clear article, just what I needed to expand my interest in plant dyes. Thank you! Happy New Year!

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