Tannins are found in leaves, wood, bark, tea and fruit. One specific tannin, Tannic acid is used to mordant cellulose (cotton & linen) fibres and fabrics before using Alum to prepare the cellulose to bind chemically with the naturally occurring dyes in plant materials. This is because Alum does not react with cellulose fibres in the same way as it does with protein fibres. In Botanical Printing, the source of Tannins is from the leaves and some flowers with the alum used in the substrate or blanket to complete the reactions.
Use Natural Dyes to first dye your fabrics prior to creating a Botanical Print. The subtle colours will provide a background for your leaf prints and tint the colours obtained from the foliage.
We features here a selection of the Fibrecrafts Natural Dyes available from George Weil. Please see our Dyeing section for the full range of Natural Dyes and Auxiliaries
Mordants for Botanical Printing