In this type of molding, raw rubber material is placed in a reservoir called the transfer pot. Then a hydraulically actuated ram forces the rubber into pre-heated mold cavities through a series of sprues. The heat necessary to facilitate vulcanization is supplied by the mold itself, as well as the process of forcing a viscous liquid (the rubber) through small passages. This results in a hot, highly viscous compound that flows easily and cures rapidly, thus increasing molding efficiency. Also, since the rubber is forced into a closed mold, the resulting flash is much less significant than would be the case in compression molding. Transfer molds are more complex than compression molds, which results in substantially higher mold costs. In addition, transfer molding generally produces more material waste. However, transfer molds can frequently be run in the same hydraulic presses utilized for compression molding. All Seals commonly employs transfer molding when bonding rubber to metal.