This week’s blog is continuing our discussion of artifact
types with relatively short periods of manufacture. These can be very useful in
dating an archaeological site or feature. Today, we will look at another form
of historic ceramic, salt-glazed stoneware emphasizing one form of decoration,
scratch blue and its variations.
Salt-glazed stonewares were a common type of ceramic in manufacture for a hundred year period
between 1685-1785, with its peak in popularity circa 1720-1770 (Edwards and
Hampson 2005:30, 34). As a durable and versatile ceramic form, salt-glazed
stoneware began to replace tin-glazed earthenware and porcelains as common
dining and tea wares in England. Their thin, dense paste made them light,
durable and attractive and the distinct “orange-peel” like textured finish aids
in identification of salt-glazed stoneware by archaeologists.
|Examples of plain white salt-glazed stoneware with “orange-peel like” glaze from Fort Hunter.
The orange-peel like finish came about through the addition of salt to the glaze on the vessel while the kiln was at the highest temperature, thus giving it the name salt-glazed stoneware. These attributes included with different types of decoration, such as “scratch blue”, allow archaeologists to narrow down the period of manufacture.
Example of scratch blue salt-glazed stoneware from Fort
Examples of scratch blue salt-glazed stoneware from Fort
Scratch blue, is called such due to the thin blue lines that
are present on the ceramic body. Produced through a process of incising or
scoring deep lines in the ceramic and neatly filling the lines with cobalt blue
oxide and wiping the excess clean before firing, the finished scratch blue
ceramic often has simple geometric or floral patterns. In production from
1744-1775, scratch blue was commonly used to decorate cups and saucers,
pitchers and punch pots (Hume 1969:117). Due to this short manufacture date
range, scratch blue salt-glazed stoneware can be a useful tool in dating an
archaeological site or feature.
Scratch blue salt-glazed stoneware fragments from a tea
cup recovered at Fort Hunter (36Da159)
Another type of incised decoration on salt-glazed stoneware, called scratch brown, is an earlier form of scratch decoration with manufacture dates between 1720 and 1730, and are rare finds (Hume 1969:117; https://apps.jefpat.maryland.gov). Following the same technique as scratch blue decoration, scratch brown uses iron oxide to fill the incised lines prior to firing.
One final variation of scratch-blue decoration found on
archaeological sites today is debased scratch blue. Using the same
manufacturing techniques as scratch blue stoneware, debased scratch blue used a
more liberal amount of the cobalt powder and the excess not wiped off for clean
striking blue lines. A later version of scratch blue stoneware debased scratch
blue dates between circa 1765 and circa 1795 (Skerry and Hood 2009:106).
Example of debased scratch
blue stoneware from Fort Hunter.
As can be seen through these brief descriptions even a small variation in decoration can make a difference on how archaeologists date and interpret a site. We hope this information has helped you see how small details can allow for a better understanding of past human behavior. Look forward to more descriptions of artifact types from Pennsylvania in future blogs. To see additional examples of ceramic types and other artifacts please visit our online collections.
What would the Farm Show be without our dugout canoe?
Recently The State Museum
participated in the Virtual 2021 Pennsylvania Farm Show with a special
"virtual booth." Check out a featured interview with Dr. Kurt
Carr talking about our 800- year-old dugout canoe and our replicas at PHMC's
virtual booth landing page.
Hume, Ivor Noel
1969 A Guide to Artifacts of Colonial America.
University of Pennsylvania Press, Philadelphia (reprint)
and Rodney Hampson
2005 White Salt-Glazed Stoneware of the British
Isles. Antique Collectors’ Club, Woodbridge, Suffolk.
E. and Suzanne Findlen Hood
2009 Salt-Glazed Stoneware in Early
America. Colonial Williamsburg Foundation, Williamsburg, Williamsburg, in
association with University Press of New England, Hanover.