Sentence:  "Overfired Glaze" This occurs when a glaze has been fired above the temperature for which it has been compounded. It may also occur if the glaze has been soaked for too long at or near the top temperature. Although the first cause is the most common, the second should not be overlooked. An <WSD>overfired</WSD> glaze may run off the object onto the kiln shelf or form a pool of glaze inside a pot. In some cases <WSD>overfired</WSD> glazes look thin because some of the glaze constituents have volatilized, or because the glaze has become so fluid that it has soaked into the body. 
Meaning of the word marked with <WSD> tags:  Fired at a high (or excessively high) temperature.