Building phase: the inspected/buffed casing will add a thin layer of cushion gum, which acts as an adherent between the vulcanized pre-cured tread and the tire.  After the cushion gum has been administrated the retreader will add the vulcanized pre-cured tread pattern over top splicing the ends and holding them together with staples before entering the curing chamber.  The tire is then placed in a pressurized heated chamber by air produced through electricity, steam or hot liquid such as oil.  The prepared casing, with the new rubber in place, is put into the chamber where pressure and temperature, applied over the correct length of time, cure the cushion gum layer and bond the tread to the tire.