Alum is used as a mordant to allow paints to stick when marbling paper or fabrics. This is in the form of a kibble (small chunks as opposed to a powder, which we find works much better than the powders available). Instructions are included on how to use the alum.
Caragheenan or caragheen moss powder is also available in this shop and is used to make a size for marbling paper and fabric.
A free pdf including instructions on paper marbling and patterns will be emailed to you following your purchase of any marbling materials.