Natural pigment notes

Facts about the use of soy milk in surface design

  • Soybeans have the highest level of protein of all the legumes.
  • In Japanese textile arts such as katazome (stencil dyeing) soy milk is used as a sizing, which prepares the surface of the fabric for rice paste and prevents the dyes from wicking.
  • Soy milk is used as a binder for natural pigments, and is painted on in several layers, drying the fabric between each layer.
  • Fabrics painted with soy milk-based natural pigments should air-cure for a minimum a week before washing. Through oxidation, the soy becomes an insoluble protein polymer. If you choose to wash the paste out sooner, do so gently and do not scrub the fabric in any way. The work will continue to cure after you wash out the paste.
  • Natural pigments applied in this manner are wash-fast and light fast, and more stable in this regard than chemical-based dyes. However, as with any fine textile do not display in direct sunlight, as UV light can damage any fabric.

Mixing natural pigments for painting:

  • First, make a little paste with natural pigments (i.e. 1/2 tsp) and an equal amt. of water. Then add soy milk, i.e. 1 Tbsp. or so to start. Test your color on a swatch of your fabric, and let it dry. When you have the color you like, add another 2 parts (i.e. 2 Tbsp.) soy milk (this assumes you will be painting 3 layers of the same color).
  • The pigments settle out, so be sure to stir with your brush before each application.
  • For best results, brush the pigments on with a very dry brush, painting several layers and build up your value that way, letting the cloth dry completely between each layer.
  • Finally, you may paint accents with a watercolor brush, using a more saturated and/or darker value mix of pigment and a small bit of soy milk.

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