Defects in ceramics are of interest to potters and ceramic manufacturers because they are a major cause of financial loss. They are of interest to collectors of ceramics because they may (or may not) reduce the value of an item. They are of interest to users especially if they can cause damage or injury in use.
I (being old and having nothing else to do) decided to tell you what I remember about ceramic defects. I worked in the ceramic industry for a good part of my life.
To understand ceramic defects you should know something about ceramic processing. If you are a potter or are involved in industrial ceramic manufacturing you know about ceramic processing. For those of you who are not familiar with ceramic processing here is the listing of the ceramic processes we will discuss in this series of articles on ceramic defects:
Batching and Formulating:
Selecting a composition for the ceramic and then choosing raw materials for the batch.
We will cover this topic in more detail in Ceramic and Pottery Defects 2: Defects from Raw Materials and Batching Errors.
Forming or Making:
Shaping the part by slip casting, pressing, hand forming, injection molding, roll forming, jiggering, or any other of a number of ways available.
We will cover this topic in more detail in Ceramic and Pottery Defects 3: Defects from Forming Operations
Drying:
Controlled heating to dry the ware before firing (or just leaving it on a shelf in Arizona).
We will cover this topic in more detail in Ceramic and Pottery Defects 4: Defects Caused During Drying Operations.
Bisque Firing (or Bisk Firing) and Single Firing:
A low-temperature firing followed by a high-temperature glost or gloss firing in the Porcelain Process.
A high-temperature firing followed by a low temperature glost or gloss firing in the China Process.
A single high-temperature glost or gloss fire in the Stoneware Process.
A single lower-temperature glost or gloss firing in the Semi-vitreous Process.
We will cover this topic in more detail in Ceramic and Pottery Defects 5: Defects Caused During Bisk Firing Operations.
Glost Firing:
Firing of glazed bisk ware (see also above).
We will cover this topic in more detail in Ceramic and Pottery Defects 6: Defects Caused During Glazing and Glost Firing Operations.
Decal Firing:
Firing a decal or decals on ware.
We will cover this topic in more detail in Ceramic and Pottery Defects 7: Defects Caused During Decaling and Decal Firing.
Enamel Firing:
Firing an enamel usually on decaled ware.
We will cover this topic in more detail in Ceramic and Pottery Defects 8: Defects Caused During Enameling and Enamel Firing.
Gild Firing:
Firing gold or other precious metal decorations.
(Note: Now days, the decal may include enamel and gold so that a single firing can be used.)
We will cover this topic in more detail in Ceramic and Pottery Defects 9: Defects Caused During Gilding and Gild Firing.
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