Glaze, a glassy coating, is applied by hand-dipping or spraying. The ware is then ready for the second, or ghost firing, which takes another 24 hours. Ghost firing temperatures are 2450 degrees for stoneware and slightly lower for porcelain. Adjusting the temperature and timing of the run through the kiln can affect the final color of the ware. Too much smoke produced by impurities in the glaze can produce a yellowish color.