Ceramic Glaze Defects

Crazing consists in the appearance of network of cracks in the glaze.

Ceramic glaze defects.

Blisters appear as large bubbles either just below or penetrating the surface leaving sharp rough edges that collect dirt. Glazes that are applied too heavily or too lightly are the cause of any number of glaze defects including pitting crawling color variation and rough spots. The thermal expansion of the glaze is too close or higher than the body. An adjustment of the dilatation of either the body or the glaze is required.

Usually crazing is due to improper glaze body thermal expansion coefficient matching. If the glaze does not state lead free or leadless on the label assume it contains lead until proven otherwise. Welcome to understanding pottery chapter 19. Applying glaze too thinly can result in rough glazes and can affect the glaze s color.

Blue ridge pottery for example is well known for glaze pops. Crazing is the most common glaze defect and normally the easiest to correct. Poor application of the raw glaze to the bisqueware can lead to various glaze defects. Damage damage describes defects made through use handling cleaning or storage.

Glaze defects such as blistering are quite common when firing pottery and can be down to many things clay body glaze receipt firing method and cycle. 1 body glaze interaction problems 1 1 crazing 1 2 peeling 2 metal release 3 glaze surface defects 3 1 blisters 3 2 crawling 3 3 metal marking 3 4 pin hole 4 references 5 external links glaze defects can be as a result of the incompatibility of the body and the. Read on to get some expert pointers on how to solve five of the most common pottery glaze defects such as crawling shown at above. The surface of the glaze is very unpleasant and looks like a boiled mass of bubbles craters and pinholes.

Jennifer poellot harnetty editor. In both crazing and shivering the eradication of problems relies on matching the. Design lead glazed pieces so that they won t be used for food or drink. Defects in fired ceramics can originate with the clay the glaze.

Applying glaze too thickly can cause the glaze to run off the pot weld lids to pots and pots to kiln shelves and can result in blistering. Glaze defects are any flaws in the surface quality of a ceramic glaze its physical structure or its interaction with the body. Lead glazed pottery should be labeled as lead containing. A large bubble sometimes present as a fault in ceramic ware.

Hold the gauge on the surface of the glaze. The most reliable way to check glaze thickness is with a thickness gauge which can be purchased through an instrument supply catalogue. Lead glazes should only be used on non foodware items.