If you have glaze firing problems because of too much variation, then we recommend the following. Make sure cracks and holes are repaired to keep heat in your kiln. This allows heat to soak into the refractory and even out temperatures in the kiln. Consider changing the switching pattern to even out top and bottom temperatures. Switch the bottom to a higher setting before the top or vice versa.
Higher settings add more heat.
4. Consider adding an Orton KilnVent. These pull hot gases from the top to the bottom of the kiln and cut most temperature variations in half. Hoods above the kiln will not help temperature uniformity problems. Lusters are metal-based transparent overglazes available in rainbow colors. They are applied over gloss, satin and matte glazes as well as porcelain bisque.