Bone China

Defining Attributes

Bone china is porcelain whose high translucency comes from the inclusion in the paste of calcined bone ash.  It is considered to be a “porcelain hybrid” (Owen 2002:51), since its paste falls between that of hard and soft paste porcelains. Under short and mid-range ultraviolet light, the glazed surface of bone china appears blueish white.  

Chronology

The initial development of bone china in the 1790s can be attributed to British potter Josiah Spode.  He was producing limited quantities as early as 1794 (Hughes 1968:40), although bone china did not begin production at a commercial scale until later that same decade.  At that time, it was known as Stoke China (Cushion and Cushion 1992:237), with the designation “bone china” beginning around 1800 (Spode 2016).  Spode’s product was soon copied by many other British manufacturers, including Minton, Coalport, Davenport, Derby, Wedgwood, Herculaneum and Worcester.  Spode also developed a variety of bone china known as Felspar Porcelain in 1821 (Spode 2016).  This new variant became the standard for English bone china from that point on.

Both economical and practical, bone china had become the standard porcelain body produced in England within ten years of its introduction.  Heavy import duties that raised the price of Chinese porcelain, as well as the patronage of the Prince of Wales, helped increase public demand for bone china, which found a ready market with the growing merchant and professional classes.  

Much bone china is unmarked, making it difficult to date with accuracy.  North American manufacturers, like Lenox, also produced bone china, although this production began around the turn of the 20th century and was never a major focus (Majewski and O’Brien 1987; Venable et al. 2000:140).  If a marked piece of bone china includes the wording “bone china”, the piece dates to the 20th century.

Description

Fabric
The standard formula for bone china is 25% china clay (kaolin), 25% Cornish stone, and 50% bone ash.  This non-frit formula resulted in a body that was intermediate between the hard paste of Chinese origin and the soft paste porcelains being made in England. The calcined cow bone was responsible for the highly translucent nature of the ivory white body.  A direct source of light will pass easily through even the thickest fragment of bone china.

Bone china is stronger than hard paste porcelain and does not chip as easily as either soft paste or hard paste porcelain.  The paste may appear dense and finely-grained, and broken sherd surfaces and cracks are more likely than hard paste porcelain to exhibit brown staining.  Early bone china, particularly from minor manufacturers, may have small black flecks apparent in the paste (Hughes 1968:41).

Glaze
The transparent glaze used for bone china consisted of silica, lead oxide and potash.  This glaze, which has a tendency toward crazing, is free from the hard, glass-like quality of Chinese porcelain.

Decoration
Applied decoration on bone china took a number of forms: overglaze painting, transfer printing over and under the glaze, bat printing, painted luster, gold gilt, and sprig molding. Quality, form and decoration varied from factory to factory. After around 1820, some manufacturers used large expanses of brilliant ground colors, over and around which they added detailed paintings of fruit, flowers and landscapes and lavish gilding. Others factories produced simply ornamented pieces. Bone china is also characterized by molded rims and handles.  Undecorated bone china could be purchased by china sellers, who provided customers with a range of samples and illustrations of decorative motifs.  Independent enamellers then painted the bone china according to customer desires (Hughes 1968:42).

Chinese and Japanese inspired motifs on bone china became popular in the early 19th century and remained so until the 1820s (Hughes 1968:42).  Spode produced generously gilded Japanese inspired Imari designs.  

Elaborately decorated and gilded bone china as described above is uncommon in nineteenth-century North American archaeological contexts.  Instead, bone china is more likely to be decorated simply with sprig molding in cobalt stained clays, small painted floral motifs in luster and overglaze enamels, and simple bands of gilt or gilt highlighting of shallow molded rim treatments.

Form
Bone china was produced in a wide variety of vessel forms. In addition to the standard tea and tableware, a number of specialized forms—asparagus trays, butter tubs, candlesticks, cheese dishes, toast racks, rouge-pots, inkstands, custard cups and chestnut vases—were produced. During the 1830s, toilet and trinket sets and ornamental ewers began to be made (Hughes 1968:43).  The most commonly found vessels on North American archaeological sites are cups, saucers and other tea-related vessels.

References

Cushion and Cushion 1992; Hughes 1968; Majewski and O’Brien 1987; Owen 2002; Spode 2016; Venable et al. 2000