A BASIC PRIMER on CERAMIC TYPES

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Many of us love collecting beach ceramics, in part because the patterns, glazes and colors can be so magical. Many of us also like the history quest that specific shards lead us on via their particular patterns, mold marks or maker’s marks on the back.  Perhaps the first step in identifying ceramic shards is to learn about the different categories into which they fit.  This makes it easier to date and determine their origin.

“Ceramics” refers to items made of fired clay. It s a broad term that can be divided into several primary categories: porcelain, earthenware and stoneware. The main difference between these categories is the specific composition of component materials and the firing temperatures.

Note: Although the term ‘Pottery’ can be regarded similarly as ‘ceramics,’ it is generally used to refer mostly to stoneware (also known as clayware) and earthenware, leaving Porcelain in a category by itself.

EARTHENWARE is in general usage, a kind of object—e.g., vessel, figure, or structural form—made from fairly coarse, porous clay that, when fired, assumes a color ranging from dull ochre to brownish red to red that is usually is left unglazed. Bricks and plant pots are earthenware. So is Terra Cotta (which means ‘baked earth’), which is used chiefly as an ornamental building material, and in modeling (i.e. many floor tiles). Although earthenware was frequently used in kitchens in the early 1700s, the pieces became mostly decorative after the introduction of stoneware in the late 1700s because stoneware was more durable. Smoothed chunks of old brick and floor tiles such as those found on Italian beaches are examples of earthenware.

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STONEWARE is made from stoneware clay or non-refractory fire clay, which is fired at high temperatures to produce a dense, impermeable and hard enough surface to resist scratching by a steel point. Stoneware is opaque and is usually grey or brownish in color. Though it doesn’t have to be, it is normally glazed. Stoneware was the predominant house ware of 19th century North America and shards of jugs, mugs, crocks and insulators are commonly found up and down the east coast from Prince Edward Island and New Brunswick, Canada south to South Carolina, USA.

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PORCELAIN: There are three types of porcelain:

Hard-paste (or True) Porcelain, which is a high-fired ceramic composed of Kaolin (white clay) and Petunse (a feldspathic rock). Kaolin is refractory and binds a piece together while in the kiln and Petunse fuses into a natural kind of glass that gives hard-paste porcelain its smoothness, brilliance, and a translucent quality. The Chinese were the first to develop true porcelain, and Chinese export-ware became much sought after from the 17th through 19th centuries by aristocratic and/or wealthy Europeans and Americans.

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Soft-Paste (or Artificial) Porcelain: Soft-paste porcelains date back to early attempts by European potters to replicate Chinese porcelain, which they did by mixing clay and ground-up glass (frit). Nowadays, they are composed of the same materials as Hard Paste porcelains but are fired at  lower temperatures so they tend to be more granular and porous. The surface of soft paste porcelain is somewhat less white and brilliant/ and it has an almost silky feel to the touch.

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Bone China consists of Kaolin and Petunse with at least a 30% mixture of bone ash (ashes from burned animal bones, mostly cattle) added. Bone China is fired at lower temperatures like soft-paste porcelain so there is less breakage, but it shares a similar translucence and brilliance as True Porcelain.

When you find porcelain shards on the beach, how can you tell one type of shard from another? Examine an unglazed exposed or broken piece to determine how porous or granular the interior body is.

Soft Paste = Granularity. The shards tend to break down beneath the glaze.

Hard Paste = the most durable, compact and fused. Feels cold to the touch than other porcelains. Place different porcelain shards on your cheek to see if you can note the difference in temperature.

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