Natural Dyes: Captured in Print

About Mordants

The word mordant comes from the Latin word mordere, to bite. Mordants are metallic salts that cause fibers to receive color by absorbing dye. The chemical bonding of fiber, mordant and dye produces the final color on the fabric. Applying the mordant may be done before, during or after dyeing. Mordants are necessary, for without them, natural dyes will fade badly. Common mordants for natural dyes are alum (aluminium potassium sulfate), chrome (potassium dichromate), copperas (ferrous sulfate) and tannic acid.

We’ve used alum and tannic acid here because of their relatively low toxicity. Chrome and copper are very toxic, and tin is moderately toxic; iron is toxic when ingested in large quantities. Although you may wish to avoid the latter mordants because of their toxicity, they do enable you to achieve different colors or degrees of lightfastness.

If you wish to use these chemicals, you must observe strict, safe dye procedures and work in a well-ventilated area, away from the kitchen, kids and pets. Use utensils dedicated to dyeing (don’t boil the soup in the pot you dyed your fabric in). When handling powders, wear a facemask. Wear rubber gloves when handling all materials.

Materials

• Hammer or mallet
• 2 plastic, glass or ceramic containers that will hold at least 1½ quarts each
• Artist’s paint brush
• Paper towels
• Firm, stable work surface
• Thin cotton or linen fabric washed well to remove sizing (synthetic or synthetic blend fabrics will not take the color well)
• Mordants
• 2 quarts hot tap water
• Fresh leaves

1. Assemble all your materials and prepare the chemical baths. In one of your nonreactive containers, mix 1 tablespoon of alum with 1 quart of hot tap water. In the second container, mix 1 tablespoon tannic acid with 1 quart of hot tap water.
2. Pick fresh leaves for printing. Firm, crisp leaves work best. It’s not the chlorophyll in the leaf that makes the lasting image, so a leaf’s color won’t necessarily predict how distinct a print it will make. Plan to experiment with lots of different ones. If the leaves are very juicy or fleshy, the image tends to smear and fade. If they are dry or woody (like rosemary), they won’t print. We used herbs here but any leaves can be used. Try flowers, too.
3. Place a leaf, vein side up, on your work surface. Lay the fabric, right side down facing the leaf, on top and cover with a piece of paper towel. The paper towel absorbs the slight stain picked up by the hammerhead as you pound, thus keeping your cloth clean and your image sharp. Hold everything firmly in place with one hand to avoid smearing, and pound the area over the leaf. Your hammer or mallet should have an even surface or it will be difficult to cover the whole leaf evenly. Pound hard enough to release the green juices from the leaf, but not hard enough to damage the fabric. When the image is distinct, lift the paper towel and the fabric off the leaf and peel away any remaining bits of leaf. Be careful not to smear the edges.
4. To bond the color to the fabric, it must be submerged in a mordant bath (or you can paint mordant solution on the image area with a paintbrush). We used both alum and tannic acid baths because we found that alum alone did not hold the print in sunlight. We dipped our print in the tannic acid bath for two minutes and then in the alum bath for two minutes, rinsing the fabric in water between baths. After mordanting, rinse thoroughly under running water; then wash in warm, sudsy water, rinse well, dry and press.

Alum is available in the spice section at your local grocery store. Other mordant chemicals are available from hobby stores and artist supply stores as well as the following sources:

Earth Guild
33 Haywood St.
Asheville, NC 28801
(800) 327-8448
www.earthguild.com

The Science Company
95 Lincoln St.
Denver, CO 80203
(800) 372-6726
www.sciencecompany.com