Mordants for Natural Dyes

Mordants for setting the colours from natural dyes.

Mordants link chemically with fibre to create attachment points which bond with the colour extracted from natural dyes. They are used to help make colours light and wash fast, and different mordants will modify colours by brightening, tinting or saddening. Use mordants also to set the colours from flowers and leaves during the process of Botanical Eco Printing.

Materials can be pre-soaked in a mordant and left damp prior to dyeing. The mordants can also be added to the dye bath while the dye is being simmered. Mordanting materials before and after dyeing with natural dyes will add extra fastness, Copper, Tin and Iron can be used as an after treatment to adjust colours.

Alum mordant is the most commonly used mordant in natural dyeing because it does not modify colours. It does not react with cellulose fibres (i.e. cotton and linen) in the same way as it does with protein fibres such as wool and silk. Tannin is used to pre-mordant the cellulose before using the Alum mordant to make this chemical reaction complete. Most tannins will leave a residue of colour and tint the colour from the natural dye, and this may be a desired effect. To avoid this and to retain the fibre’s natural colour, Aluminium Lactate can be used as an alternative mordant for cellulose. Sources of Tannin can be found with our Natural Dyes and Natural Dye Extracts. Additional modifiers for natural dyeing, can be seen in Dye Assistants, Modifiers & Mediums