Below is a list of common firing faults. While helpful, this list is not for instructional use and should only be used to help identify faults that may have occurred.
For comprehensive firing information on your particular type of ware and color, we suggest contacting the manufacturer or distributor. For more general instruction we suggest that you seek training from a qualified teacher.
CRAZING AND CRACKING
Crazing is recognized by many hairline cracks on the glazed surface after the ware has been fired. This will not necessarily occur immediately after the final firing but over a period of time the hairline cracks will become visible. Crazing and cracking could be caused by:
1. Bisque or greenware that has not been thoroughly fired. Greenware must be completely dry before doing a bisque firing. The piece should be fired to a cone 03 or 04 making sure the pieces are not crowded and adequate heat circulation surrounds all the pieces. If the pieces are not thoroughly fired, moisture will be trapped inside the ware. This will cause the crazing and cracking to occur during the glaze firing. The moisture and gases are escaping and disrupt the smooth glaze finish. Continue reading