The object of this test was to discover what happens when glass which has already been stained is fired a second time. The upper sample is the tin side of float glass; the lower sample is Lamberts. Two pieces of each glass were to 1050°F and held for 2 hours. After cooling the clay body of the stain was removed and the right hand sample was fired a second time and held for 1 hour. The effect is subtle but the stain continues to disperse into the glass.