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Wool requires soaking, washing and cleaning from waxes, dirt and oils. The next step is to "mordant" the wool.

The word "mordant" comes from the latin "mordere" meaning "to bite." Mordants are mineral salts that connect inside the fibers of wool, assuring correct connection between the biochromes (the natural dye colorant) and the wool. They are used to ensure light- and wash-fastness, meaning to prevent the color/print/dye to start bleeding, brighting/saddening or any unwanted changes to the colors of the dyed fibers.

In history a wide variety of interesting substances were used as mordants to ensure color fastness, including arsenic, chrome, tin and other heavy metals and chemicals.

Below a short description of the necessary "mordant" steps to continue towards two options for coloring:

Mordant dyes Ecoprinting



Start by weighing the amount of dry fibres, this will be the WOF (weigh of fibers). Note donw the amount of fibers you will be mordanting and later dyeing.

step1 weighing the dry wool fibers, yarns or fabric

  • MORDANTING Measure 15% of WOF of Alum and 5% WOF of Creme of Tartar. Creme of Tartar will help in adjusting the ideal pH for wool and also by protect the fibre during the mordanting process.

step2 measuring the amount of alum and creme of tartar in relation to the WOF

  • MORDANTING Add both Alum and Creme of Tartar to a pot full of water and bring to simmer, until they are fully dissolved. Wet the wool fibres before adding them to the pot.

step3 adding alum and creme of tartar to the water pot

  • MORDANTING Simmer for 1 hour. Optional: to guarantee maximum mordant absorption you can leave the fibres in the mordant bath overnight. Be aware never to boil protein fibres as they can easily get damaged by excessive heat

step4 simmering all fibers

  • RINSING THE WOOL Remove the yarns or fabric from the mordant bath and rinse thoroughly in running water. Be careful not to give temperature shock to animal fibres, if the bath is still warm, use warm water to rinse as well, or let it cool down. step5rinsing the wool

Last update: September 6, 2022