ALUM MORDANT ~ necessary for most plant dyes to ensure colour fastness.
Alum is considered the least harmful or safest when it come to mordants used in plant dyeing. What many don't know is that Alum occurs naturally in nature and some plants, like horsetail, contain Alum.
*Alum has long been used as an additive to both foods and drinking water.
Weigh your DRY textile material.
ALUM: Divide the weight of the material to dye by four. Weight out that much alum mordant. A scant two tablespoons equals one ounce of alum.
Add Alum to the pot, and almost fill with warm water. Leave enough room to add the wet textile material. Stir until fully dissolved.
*You can leave the wool in for 24- 72 hours - cold mordanting.
** Or you can heat to 80 degrees Celcius for one hour.
Rinse and dry.