Botanical Dye Studio #02: Mordant for Protein Fibers

Tips & Tricks from our Botanical Dye Studio – Dye for Protein Fibers

When dyeing with botanical dyes, you need a fixative, known in technical terms as a mordant. The mordant allows the dyes to bond more effectively with the fibers chemically. This makes the fabric more resistant to light, washing, and friction. Natural dyes only adhere to natural fibers, and the mordant is a kind of layer that the plant substances can bond with. This layer is often created using aluminum sulfate, also known as alum. Plant and animal fibers are morded using different amounts, and there are many different mordant options and recipes. Depending on the mordant and the substance used, the botanical colors appear in different shades. To get you started, I'll give you two simple recipes. Today we'll start with a mordant recipe for animal fibers.

Mordant for protein fibers

Mordant: Alum 15% WOF (WOF = weight of fiber, the dry weight of your fabric)
Method: Stainless steel pot & stove

1. After washing, weigh your dry fabric. To determine the correct amount of alum, you need 15% of the dry weight of your fabric. For 100g of fabric, that's 15g of alum.
2. Fill a pot with enough water so that your fabric can move freely. Dissolve the alum in a separate container with hot water before adding it to the pot. Stir well, then place your wet fabric in the mordant bath and slowly heat it to 60°C. Maintain this temperature for one hour. Move your fabric occasionally and make sure it doesn't get too hot!
3. After an hour in the mordanting bath, you can let your fabric cool before removing it, or you can let the fabric soak in the mordanting bath until the next day. This will lead to even better results.
4. Your fabric is now ready to dye. You can either let it dry in a dark place or use it while still damp.

Have fun trying it out! Our next article will feature a recipe for cellulose fibers.