Ceramic Glaze Defects

Welcome to understanding pottery chapter 19.

Ceramic glaze defects.

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. The surface of the glaze is very unpleasant and looks like a boiled mass of bubbles craters and pinholes. An adjustment of the dilatation of either the body or the glaze is required. Lead glazes should only be used on non foodware items.

Jennifer poellot harnetty editor. Hold the gauge on the surface of the glaze. 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. Design lead glazed pieces so that they won t be used for food or drink.

Poor application of the raw glaze to the bisqueware can lead to various glaze defects. In both crazing and shivering the eradication of problems relies on matching the. 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. A large bubble sometimes present as a fault in ceramic ware.

Usually crazing is due to improper glaze body thermal expansion coefficient matching. The most reliable way to check glaze thickness is with a thickness gauge which can be purchased through an instrument supply catalogue. Glaze defects are any flaws in the surface quality of a ceramic glaze its physical structure or its interaction with the body. There seem to be so many ways that bad things can happen to good pots.

Defects in fired ceramics can originate with the clay the glaze. If the glaze does not state lead free or leadless on the label assume it contains lead until proven otherwise. Applying glaze too thinly can result in rough glazes and can affect the glaze s color. Blisters appear as large bubbles either just below or penetrating the surface leaving sharp rough edges that collect dirt.

The presence of a variety of kiln marks on some types of pottery is common and is not generally considered a flaw but again should be described. Glaze surface defects blisters. 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. Crazing consists in the appearance of network of cracks in the glaze.

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. Damage damage describes defects made through use handling cleaning or storage. Lead glazed pottery should be labeled as lead containing.