To use alum for skin tightening, start by mixing a small amount of alum powder with water or rose water to form a smooth paste. Apply this paste evenly to your face or areas where you want firmer skin, avoiding sensitive areas like the eyes. Leave it on for about 10–15 minutes, during which you may feel a tightening sensation as the alum works to contract the skin and reduce pore size... https://www.vedikroots.com/blogs/skin-and-hair-care/alum-for-skin