ALUM (potassium aluminum sulfate) is a common mordant used to allow fabric to hold the color better and be more lightfast. It may be used with cream of tartar, which helps evenness and brightens slightly. Three table spoons of alum and one of cream of tartar is a good start. Be sure to weigh your wool. Too much alum makes wool sticky, and the stickiness will not come out. Alum mordanted wool stores well, wet or dry. Though, you should never store your wool wet for very long.
One pound of = three table spoons of Alum and one of Cream of Tartar.
Use a non-reactive pot enamel (unchipped) or stainless steel. Brass, copper or iron pots will do their own mordanting, providing special effects you may not care for.
**REMEMBER: DO NOT use the same pot you cook with to mordant your wool.**
Bring your pot of water to a simmer.
Then, mix the cream of tarter with a small amount of boiling water and add to the simmering pot of water. Next, mix your alum with a small amount of boiling water and then add to the pot and stir with a wooden implement not to be used for food.
Take your CLEAN, pre soaked wool and add it to the pot.
Keep your pot at a simmer for a good hour. DO NOT BOIL. Stir occasionally VERY SLOWLY & GENTLY. (HEAT and AGITATION cause FELTING.)
Remove pot from heat and let cool, preferably over night. Remove wool from pot and rinse well. It is ready to be dyed. You may bring your wool to class still wet, as it will need to be thoroughly soaked prior to being dyed. But, remember we are only dye one pound per person. I would suggest you cut the pound of wool into decent chunks to try each of the different dye pots, and still be large enough to use.