Mordant for Natural Dying
Many natural dyes require the use of a mordant to achieve the most durable and long-lasting colours. Mordanting prepares the fibres to bond with natural dyes and is typically a separate immersion bath for the fibres. The technique is simple: measure the mordant, dissolve in water, and add to a dye pot or bucket or tub filled with water. Add the fibres for a period of time, then transfer to dye bath. Although many substances can be used for mordanting, the most sustainable mordants are considered to be aluminium potassium sulphate for protein (wool) and aluminium acetate for cellulose (cotton, linen, bamboo, etc.) fibres, as well as for protein/cellulose blends, like wool/hemp, silk/bamboo and silk/cotton.
Alum Mordants (Article)