Its totally unscientific use of alum. Alum has nothing to do to tighten the vaginal walls. Alum has antiseptic effect, so, use of alum in the female genitalia can cause death of many bacteria that are present to control the pH. In the absence of these bacteria, normal secretions of female genitalia are stopped that can change the pH leading to growth of many pathogen bacteria. So, alum should not be used in the female genitalia.
