Gas Fired Functional Ware All of my gas-fired pieces are glazed with production glazes and my own glazes; typically, inside and out. Like the wood-fired pieces, they are fired to 2300-2400 degrees F (+/-). The gas kiln is fueled with natural gas and temperature and air flow are controlled with burners, blowers and a damper system. It's a much faster climb to temperature than the wood-fired kiln however, taking a mere 8-10 hours from start to finish. This kiln cools down for 2 days before it is opened.