Silk can be solid color dyed with cold water using the same tub dyeing method as for cotton. The colors on silk are not as predictable nor the same as on cotton. Mixed colors tend to shift one way or another. But it is so easy compared to hot dyeing that it is well worth trying. Soda ash will take away some of the sheen of silk and can give silk more of a stonewashed appearance unless exposure is limited. To avoid that, try the vinegar method below.
Wool cannot be dyed with the cotton method. The method below yields beautiful colors on both wool and silk, although silk usually takes the dye better than wool. Fiber Reactive dyes will exhaust better on silk as well. Fiber reactive dyes give the best results when used on high-quality, white, pure virgin wool or 100% white silk. Reused fabrics or yarns may contain impurities which will interfere with the dye process. Oils or gum on the fabric or yarn will prevent the dye from taking uniformly. Fabric or yarns of an existing color will be blended with the dye color used. On silk, the colors shift. Best to do a test first. Fiber Reactive blacks do not yield black on silk. Use a black silk dye.
The following recipe is per 1 pound (450 gm.) of dry weight of wool or silk.
1. Place 1 to 5 teaspoons (3-15 gm.) of dye (depending on the shade desired) into a one-quart Pyrex measuring cup, add a small amount of cold water and work into a smooth paste with a stainless steel or plastic spoon. Add 1 cup of water at 60 degrees C (140 degrees F) to this dye paste. Stir well to dissolve all the dye and pour into the dyebath container (should be stainless steel, glass, or enamel, not aluminum or copper).
2. Dissolve 3 to 9 tablespoons (180-270 gm.) of plain salt (depending on the intensity desired) in 2 cups of warm water and add to the dyebath. Add the fabric. Add enough water to cover the material plus a little extra to allow the yarn or fabric to move freely in the dyebath.
3. Place the dyebath container on the stove and heat gradually to a simmer (just below boiling) and hold there for 10 minutes, stirring frequently. Add 2/3 cup white vinegar or equivalent concentration of Citric Acid and continue to simmer for another 10 minutes, stirring occasionally.
4. Remove from heat, rinse in hot tapwater and wash with Synthrapol. Rinse until free of dye, gradually lowering the temperature of the rinse water to that of the room. Remember that sudden changes in temperature can damage the wool and cause it to felt up. Heat and cool slowly!