Ceramic Glaze Defects Crazing

Crazing can be present in varying degrees.

Ceramic glaze defects crazing.

All ceramic bodies change in size during heating firing and cooling. Commonly called guan kuan crackle the ru guan and ge ware were all beautiful examples of crazing as a decorative technique. 2 caused by glaze body fit glaze fits too tightly to clay body. Crazing is a term used to reference fine cracks that can be found in the glaze of pottery or china.

What is desired is for the glaze to shrink a little more than the body during cooling. Crazing consists in the appearance of network of cracks in the glaze. Glaze defects are any flaws in the surface quality of a ceramic glaze its physical structure or its interaction with the body. Poor application of the raw glaze to the bisqueware can lead to various glaze defects.

Usually crazing is due to improper glaze body thermal expansion coefficient matching. The thermal expansion of the glaze is too close or higher than the body. It is caused by tensile stresses greater than the glaze is able to withstand. Glaze crazing or glaze crackle is a network of lines or cracks in the fired glazed surface.

A craze pattern can develop immediately after removal from the kiln or years later. Glaze defects can be as a result of the incompatibility of the body and the selected glaze examples including crazing and peeling. Crazing is a spider web pattern of cracks penetrating the glaze. A mismatch between the thermal.

Immediate crazing 1 appears when piece removed from kiln or shortly thereafter. Applying glaze too thinly can result in rough glazes and can affect the glaze s color. Crazing and shivering or peeling of ffc. Common reasons for such stresses are.

An adjustment of the dilatation of either the body or the glaze is required. It happens when a glaze is under tension. Crazing is the most common glaze defect and normally the easiest to correct. Crazing crazing a network of spidery cracks in the surface of the glaze.

Crazing is often thought of as a glaze defect but as nigel wood describes in his book chinese glazes the song dynasty potters are thought to be the first to treat crazing as a decorative effect. May be described in estimated percentages or by location as in light crazing over 100 of the item or heavy crazing on the pedestal only light crazing very light and only visible upon close inspection. Sometimes items may have a couple of crazing lines on one side and not the other other times the crazing can look like a spider web and cover the entire item. We lakeside pottery know of cases where the pinging sounds of newly developed crazing lines go for many years.

In both crazing and shivering the eradication of problems relies on matching the thermal expansion characteristics of both body and glaze.