Some will use them in Pipes where the base of the chamber is wearing thin from use... Another method for this same problem involves the use of 'load stones', which are small chunks of clay, to place in the bottom of the chamber before loading the Pipe. They look a lot like cat litter & can also be found as Meerschaum granules, used for the same purpose. Still another technique involves the use of 'Pipe mud' to build up the bottom of the chamber. It is made from water & Cigar ash.