OVERGLAZE FIRING
Sometimes, potters choose to do additional firings to achiever color and surface effects not possible in the glaze firing. These effects include lusters, china paints and decals. These overglaze techniques are fired at extremely low temperature (1300 degrees F.) and because of that, brighter colors and lusters are possible than can be achieved at 2350 degrees F. These are, loosely speaking, very low fire glazes that are melted atop the previously fired high temperature glaze. At this low temperature, the underlying glaze does not even melt, instead the luster, china paint, or decal melt onto the glaze and fuse, semi-permanently. This is the major disadvantage of this technique. The overglazes are not as permanent as high temperature glazes. Abrasion will erode this coating, and eventually, the overglaze will be gone or muted by time. Still, unusual and exotic effects are possible, and for this reason, potters are interested in this area. Some techniques, like china painting, often involve multiple overglaze firings, layering one color on top of another as complicated designs emerge