Ceramic Glaze Defects

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.

Ceramic glaze defects.

The thermal expansion of the glaze is too close or higher than the body. 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. Usually crazing is due to improper glaze body thermal expansion coefficient matching. Crazing consists in the appearance of network of cracks in the glaze.

Defects in fired ceramics can originate with the clay the glaze. In both crazing and shivering the eradication of problems relies on matching the. Jennifer poellot harnetty editor. 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. Poor application of the raw glaze to the bisqueware can lead to various 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. 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.

There seem to be so many ways that bad things can happen to good pots. Lead glazed pottery should be labeled as lead containing. Hold the gauge on the surface of 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.

Blisters appear as large bubbles either just below or penetrating the surface leaving sharp rough edges that collect dirt. An adjustment of the dilatation of either the body or the glaze is required. The surface of the glaze is very unpleasant and looks like a boiled mass of bubbles craters and pinholes. Blue ridge pottery for example is well known for glaze pops.

Lead glazes should only be used on non foodware items. The most reliable way to check glaze thickness is with a thickness gauge which can be purchased through an instrument supply catalogue. Applying glaze too thinly can result in rough glazes and can affect the glaze s color. Glaze defects are any flaws in the surface quality of a ceramic glaze its physical structure or its interaction with the body.

If the glaze does not state lead free or leadless on the label assume it contains lead until proven otherwise. Damage damage describes defects made through use handling cleaning or storage. Design lead glazed pieces so that they won t be used for food or drink.