This utsava is penitential as well as propitiatory and its main objective is to get rid of the evil that might have been caused due to omissions and commissions in the performance of various rituals throughout the year.
The Agni Purana specifies that the first day of a lunar fortnight either in the beginning of the month of Aashada or the end of the Krithika should be chosen for performing pavitrotsava.
The Pradhana khumba is taken to the main deity on the concluding day and the augmented spiritual power is believed to be transmitted to the Moola Vigraha (Kumbha Aavaahanam).
[2] The rituals on the three days include Thirumanjanam and Homam (prayer to sacrificial fire) to the main deity as well as primary idols of Lord Venkateswara.
Pavitras, the garlands made from special thread are taken in a procession and used to decorate Lord Malayappa swami and his consorts on the second day.
The stone inscription found on the northern wall of the Vagapadi verandah in the first Prakaara of the Tirumala temple gives a very detailed account.