Aluminum sulfate is a very common and very versatile industrial chemical. It can be hazardous or safe, depending on the use and the amount used. Its many uses include: lake water cleaning and clearing, potable water purification, litter treatment, soil acidifying, paper making, turning hydrangeas blossoms blue, to stop the bleeding from shaving cuts (it’s a coagulant), sewage treatment, as an additive in canned fish, battery rejuvenation, and more. It can be found in baking powder. It is also used to manufacture other aluminum compounds. There are numerous other uses for this chemical compound.
The compound looks like a dry white or off-white abrasive crystalline salt. The salt has the following formula: Al2(SO4)3. It can occur naturally but can be made synthetically as well. The compound is created by combining sulfuric acid with aluminum hydroxide. It’s non-flammable. It’s a readily hydrolyzed acidic salt of medium acidity. Aluminum sulfate is a reagent and electrolyte. As a coagulant, it is stronger that aluminum nitrate.
As an acidifying agent, such as for the use in the garden, it acts very fast. Gardeners can easily find this cheap compound at their local garden nurseries. The compound can be added to fertilizer or sold separately. It may be used as is or mixed with water (it’s a water soluble mineral). Note that you need to be careful when using it as a soil acidifier since overuse can change your soil pH. Not only can it be used to acidify the soil, but also to do achieve special effects with some flowers, such as to turn hydrangeas blossoms blue.
As a vasoconstrictor and coagulator, aluminum sulfate restricts the flow of blood where it is applied. So, some people actually use it with cuts to stop the bleeding fast. However, one should be cautious not to ingest it or get it in their eyes for example – it’s a moderate to severe mucosa irritant.