Uses of Potash Alum
Fire Retardant
The use of potassium alum for textiles, wood and paperless flame resistance is a fire-retardant.
Tanning
For leather tanning, potassium alum is used to extract moisture from the hide and avoid rotting. Alum is not covered and can be washed out, as compared to tannic acid.
Iron and Steel Dissolving
This aluminium solution has the property that steels are dissolved without affecting aluminium or base metals. For machined castings of steel parts of machinery, alum solutions can be used.
Gourmet Food
Potassium alum may be an acidic component in baking powder to provide a second leavening step at high temperatures (although sodium alum is more widely used for this purpose). Bakers in England made bread whiter with alum during the 1800s.
Used for Dyeing
Alum was used to form a permanent link between natural textile fibres like wool and dye, as mordant.
Pigmentation of the Lake
Aluminium hydroxide from alum acts as a base for most lake pigments.
Blocking Chemicals
Since remote antiquity, potassium alum was used for purifying turbid liquids. The drinking water and industrial water systems, effluent treatment, and post-storm lake procedures continue to be commonly used for the treatment of pollutants in precipitation.
Water is applied to the domestic wastewaters roughly 30 to 40 ppm of alum, but more commonly to the industrial wastewater to clump negative particles into the flocs and float them up to the liquid bottom, or more conveniently filter them out of liquid before further filtration and disinfection of the water.