At Ceres we often use Potassium Aluminium Sulphate (alum), as the mordant to increase colourfastness and lightfastness of natural dyes. A synthesised version of crystal chemically prised from rock and shale and prized by emperors, kings and popes. Ancient trades of empires long fallen, and secrets stolen in tall-ship heists. Pollution and corruption in the textiles industry already apparent a Millenia ago.
The Symplocos cochinchinensis tree accumulates aluminium from the soil, and fallen leaves become a rich source of alum. Use of this plant derived mordant helps protect the endangered forests of Indonesia and offers an alternative to chemical mordants.
We did some tests to understand how well the symplocos alum performed alongside synthetic alum.
Printed pastes from top to bottom:
Madder and symplocos
Madder and alum and calcium carbonate
Madder and alum
Modifier stripes from left to right on each sample are citric acid, sodium carbonate, ferrous sulphate.
Symplocos is as wash-fast as alum, but it’s yellower base colour makes it better with the warmer colours.