For best results I buy silk fabric which is “Prepared for Dyeing” (PFD), as some silks are covered with Teflon and do not take up the dye well. If buying silk fibre, make sure it is de-gummed silk, if in doubt ask the supplier.
Weigh the silk, using no more than 100g of silk for a 10 litre saucepan and wash it by hand or on the silk setting of the washing machine using silk washing liquid.
Leave the silk to soak in hot tap water overnight or for at least an hour.
Next weigh the alum, using 6% of the weight of dry silk (i.e. for 100g of silk use 6g of alum). Put the alum in a small container and pour boiling water into the container. Stir it well until the alum has dissolved. Buy alum mordant here.
Fill a 10 litre saucepan ¾ full with hot tap water, add the dissolved alum and stir well. Then I add the pre-soaked fibres, which are usually warm from the tap water. Wearing rubber gloves, I work the silk well into the mordant.
Leave the silk in the pot for 48 hours without adding any heat and stir gently and occasionally.
At the end of the 48 hours take the silk from the vat and leave it to dry. Keep it for at least a week before washing it and dyeing it.
