Hide Glue - The high alkalinity of indigo vats will give wool a harsh hand and diminish the softness and sheen of silk. A solution of hide glue added to indigo vats will protect wool and silk without affecting the indigo process. One teaspoon of the Earthues hide glue powder will protect one pound of wool or silk. The hide glue powder is first soaked in a small quantity of cold water and then dissolved in boiling water before it is added to the indigo vat. Complete instructions are available upon request.