 He will then wash his hands again after the offertory—this is the ceremony that is known as the "lavabo" proper.This washing appears in both the Tridentine Mass, the 1962 edition of which is still an authorized extraordinary form of the Roman Rite), and in the post-Vatican II Mass.The reason for this "second" washing of hands probably developed from the long ceremony of receiving the loaves and vessels of wine from the people at the offertory that was used in Rome.