To mark the body with vibhuti is called bhasma snana (ash bath), which is superior to bathing in sacred waters, since it is the most purifactory.
Shaiva tradition holds that without wearing vibhuti, one should not eat or drink, much less perform any religious act like reciting the holy Vedic prayer, Gayatri. A devotee is not expected to go about with bare forehead. This holds good for all the ashramas or stages of life.
The ash gathered from the altar pit, where oblations to gods are made, is also sacred to wear. Though vibhuti is donned by Saivas, it is common to all Hindus. Even the Vaishnavites wear the sacred ash from the sacrificial altar.
The places in the body which one ought to mark with the sacred ash are said to be fifteen – head, forehead, parts of back, left and right parts of the chest, the shoulders, the sides, the elbows, the wrists the back and the stomach.
Women too wear the sacred ash. Sandalwood paste and vermilion should be worn by them over the ash and not apart from it.