Most traditional refractory spouts last for approximately one year. As the glass pours through the throat, the refractory is eventually eroded away to the point when the tube will no longer seat properly against the spout, and the flow of glass can no longer be stemmed. The best means to address this issue, and thus significantly increase the useful life of the spout, is to use a denser material that will better resist the constant erosion. Dense materials tend to be very poor in thermal shock, if the entire spout was made of such material, then the heat-up of the spout would have to be very slow to prevent cracking. A more practical solution is to use a traditional refractory for the spout body, and insert a dense material into the throat. Emhart Glass now offers its full line of refractory spouts with inserts made of either isostatically pressed zircon mullite, isostatically pressed chrome oxide, or fused cast AZS (alumina zirconia silica).