Alum – Potassium Alum – Potassium aluminum sulfate dodecahydrate
Natural dyeing – mordanting any fibers : potassium aluminum is the easiest and most popular mordant used with natural colours. It does not change the shades and is necessary for a good fixation of the natural colours.
For protein fibers (wool or silk), we recommend to use the alum associated with cream of tartar that improves the fixation of alum to the fiber.
For cellulosic fibers (cotton, linen, hemp, abaca…), we recommend to use alum in association with sodium carbonate. If you prefer to use a single product, you can also select aluminum acetate instead of alum.
Also, combinations of aluminum and iron mordants or a last (very light) iron bath after a aluminum-mordanted-colour will widely increase the number of shades.
Natural inks : potassium alum both contributes to stabilize the natural dyes molecules (by complexation) and to better develop their colour. Our plant dye extracts can be used for the preparation of natural inks, for instance in combination with arabic gum. Alum has also bacteriostatic properties on certain bacteria and plays a role on the preservation of products.
Natural paints and coatings : in lime coatings, a small proportion of alum accelerates the crystallization and hardening. It also allows to fix pigments and to deepen colours in milks, paints or lime mortars. It hardens plasters and clays.
Other uses (for instance) : treatment of leathers and tanning.