A mordant is used with most dye stuffs to help the colour stick to the fibre. If you miss this stage out the colour is often weak and not very light or wash fast.
- Mordant for Animal Fibre: Alum
- Weigh fibre to be dyed when dry.
- Wet the fibre in warm water for 1-2 hours
- Half fill a stainless steel pot with hot water
- Measure Alum Potassium Sulphate at 8% Weight of Fibre (WOF)
Example: If fabric weighs 50gsm, 8% of 50g is 8 x 50 divided by 100 = 4g If using the alum mordant solution, use 10 times the number in ml, so 40ml.
- Simmer gently, (alum solution and fibre) for 60 mins, stirring occasionally.
- Cool for 2 hours or overnight.
- Rinse fibre in cool water.
It is also possible to mordant animal fibre with alum in COLD water: Use 10% alum and steep for 12 hours.
2. Mordant for Vegetable Fibre: Tannin + Alum
- Weigh fibre dry then wet it out for 1-2 hours
- Weigh tannin (10% WOF) and dissolve in boiling water.
- Half fill a stainless steel pot with hot water + tannin solution
- Immerse fibre and steep for 1 hour at below simmer point
- Rinse fibre
- Prepare alum solution: half fill a pot with hot water
- Add Alum at 20%
- Add washing soda at 6% (dissolve in boiling water)
- Simmer and add fibre.
- Switch off heat and leave 8-24 hours, stirring occasionally.
- Rinse fibre
