To stop bleeding during a procedure, which substance should be used?

Using powder alum is the appropriate choice to stop bleeding during a procedure due to its coagulant properties. Alum, which consists of potassium aluminum sulfate, works by promoting the clotting of blood. When applied to a bleeding area, it causes the blood vessels to constrict and helps to staunch the flow of blood quickly. This makes it particularly effective for minor cuts and abrasions, which can occur during various cosmetology procedures.

Other substances listed, such as hydrogen peroxide, serve different purposes and are not effective for bleeding control. For instance, hydrogen peroxide is primarily used as an antiseptic to clean wounds and can actually impede the healing process by damaging tissue and delaying clot formation. An antiseptic solution is similar in function; while it disinfects, it does not assist in clotting the blood. Cotton balls can be useful for applying other substances or for absorbing blood, but they do not have any intrinsic coagulation properties to stop bleeding themselves.