Mordants are important to use when natural dyeing, as they help
the colour to attach to the fibres that are being dyed. Alum is
one of the most popular mordants, and is used together with
cream of tartar. Although alum and cream of tartar are easy to
obtain, we've weighed out convenient small quantities that will
be enough to act as a mordant for 100g/4oz of dyestuff and
100g/4oz of fabric/yarn.
If you're using a dyestuff like madder or logwood where the
dyebath will keep giving you colour after the first dyeing, you
may want to use this dyebath more than once. If so, you'll
need to use a mordant each time you dye something, so be sure
to buy enough for your project.
15g mordant (8g alum and 7g cream of tartar)
Bulk amounts of alum are available to order if you're unable to source this yourself.