Natural Plant-Based Mordants

By using acorns, oak galls and pomegranate rinds as plant-based mordants you can increase the color quality of your home dyeing projects.

| December 2013

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 benefit of different plant-based mordants.

Plant-Based Mordants

Certain plant materials contain high concentrations of tannic acid, or tannin, which works well as a mordant to bond color to plant-based fiber. Tannin as a mordant, especially in combination with alum, can provide a greater color range with more successful results on most vegetable fibers. Certain tannin-bearing plant materials work especially well as mordants, such as horse chestnuts, pine bark, certain roots, some leaves, acorns, oak galls, pomegranate rind, and some fruits. Among the plant-based mordants, oak galls contain the highest amount of tannic acid. Some tannin substances will bind to the fiber and stay clear, allowing the true color of the dye source to saturate the fiber. But some tannins can alter the color by making it dull, especially if the dyes are yellow, pink, or brown tones.

Acorns, oak galls, pomegranate rind, and certain leaves and bark are just a few excellent sources of plant-based mordants that will brighten your dye color. You can collect acorns and oak galls on the ground under oak trees when they are in season, and store them for later use. You can also buy oak galls from some specialty herb stores.

Acorns. Acorns can be collected under oak trees in autumn, or you can buy acorn powder from specialty herbal or grocery stores. Grind foraged acorns to a powder, removing the shells, and soak the acorn material in water for several days to get the full color intensity. Acorns create colors from light beiges to grays and teal blues.

Oak galls. Oak galls are formed where wasps have laid their eggs on oak tree branches. The galls look like balls sticking to the branch. Galls make an excellent mordant, especially for vegetable fibers, and can be collected from many kinds of trees, especially oak trees (Quercus species). Oak galls have extremely high tannin content, which is also found in plant sources like bark and leaves, and is a natural mordant. It enhances the dye color as well as improving colorfastness. Alum can be used to treat fiber with tannin in one or two dye baths to achieve even stronger color results.

Pomegranate rind. The powdered rind, or skin, of the pomegranate (Punica granatum) can be used as a tannin mordant, as well as a dye to obtain peachy yellow with alum mordant, and to get gray to moss green with iron mordant. Pomegranate rind was also used as a color source for painting medieval illuminated manuscripts. The age of the fruit affects the color of the dye: the less ripe the fruit, the greener the yellow.

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