Alum Crystals

Alum is a mordant that is used to adhere paint/pigment to paper - for marbling.

Marbling paper: Dissolve 30g of Alum in 300g of hot water. Allow to cool before applying to your paper.

For Fabric: Add 2 teaspoons of Alum to about 4 liters of hot water. Stir to dissolve and soak your fabric for 20 minutes.  Leaving fabric in longer or making the Alum too strong will make your fabric brittle.

It is also used in some recipes for paper making, although a quote from A Paper Makers Companion states: "Recipes that use alum will not produce archival papers, because alum itself is not archival. So, if you want your paper to last for centuries, don’t use a process that involves alum."