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Ceramic Raw Materials

 

In Bethabara, Moravian Potter Gottfried Aust produced two types of ceramics, white earthenware and red earthenware.  Red and white clay were both mined in Bethabara. Using these bodies, in conjunction with different slips and glazes, Aust produced 17 different types of pottery.

 

White Clay: Used to make white earthenware pottery and pipes, and for making slip and glaze. This was mined near Bethabara, but the deposit location is not known. It is sometimes also called kaolin, or pipe clay.

Red Clay: Used to make red earthenware pottery. Bethabara’s clay was much more buff colored and iron oxide was frequently added to make it redder. Red clay was mined in Bethabara, just outside of the fort’s wall near Aust’s Pottery Shop.

Silica:  The base material for glass and glaze. Because it has a melting point of 3100 degrees F, well beyond the capabilities of a ceramic kiln, it needs to be combined with a flux. Aust and the other Moravian potters harvested flint and ground it at the mill to produce silica.[1]

Lead Oxide: Used as a flux to lower the melting point of silica in glaze and slip. Called “red lead,” this common ingredient for glaze and paint was imported from Bethlehem, PA., Fort Dobbs, and lead mines on the New River near Fort Chiswell, VA. A local source on the banks of Johanna (Mill) Creek was located in 1767.

Iron Oxide: Pigment added to glaze and slip to produce shades. The potters obtained iron shavings and filings from the blacksmith. The iron oxidized during firing to produce various shades from red to brown. Iron was imported to from Bethlehem, Camden, SC, and Charleston, SC.

Copper Oxide: Pigment added to glaze and slip to produce green. Sheets of copper were recovered from Aust’s pottery shop foundation. Copper sheet was imported. In 1767 a copper deposit was found a few miles from Bethabara.

Manganese: A mineral added to red clay to produce brown bleeding dots and streaks, or to glaze to create a brown and sometimes metallic finish. Found locally in clay and rocks.

Carbon: Used to create a matte black finish. Soot was easily obtained.

Slip: Liquid mixture or slurry of clay, with silica, lead, and other materials, suspended in water. It can be used to create colored designs, coat an object, and used to weld or join two unfired pieces together, such as a handle to a body.

White Slip = White Clay + Silica + Lead Oxide

Green Slip = White Clay + Silica + Lead Oxide + Copper Oxide

Red Slip = Red Clay + Silica + Lead Oxide + Iron Oxide

Brown Slip = Red Clay + Silica + Lead Oxide + Manganese

Dark Brown to Black Slip = Red Clay + Silica + Lead Oxide + Iron Oxide + Manganese

 

Glaze: Coating which fuses to the ceramic body when fired in a kiln. The coating seals the pottery and makes it waterproof. The most basic formula consisted of approximately two parts flint to one part lead and clay combined. The exact formulas are not known.[2] Small amounts of mineral colorants could be added to produce a number of colored glazes.

Clear Glaze = Silica + White Clay + Lead Oxide

Green Glaze = Silica + White Clay + Lead Oxide + Copper Oxide

Dark Red to Brown Glaze = Silica + Red Clay + Lead Oxide + Iron Oxide

Brown to Metallic Glaze = Silica + Red Clay + Lead Oxide + Manganese

Dark Brown-Black Glaze = Silica + Red Clay + Lead Oxide + Iron Oxide + Manganese

Dull Black Glaze = Silica + Red Clay + Lead Oxide + Carbon

 

Clay, slip, and glaze combinations archaeologically recovered in Bethabara:[3]

White Earthenware:

  • Cream/yellow ware
  • Brown and yellow ware
  • Green and yellow ware
  • Green ware

 

Red Earthenware:

  • Glazed red ware
  • Glazed brown ware
  • Glazed metallic brown ware
  • Glazed dull black and red ware
  • Glazed red and brown ware
  • Glazed yellow and red slipware
  • Glazed green and yellow slipware
  • Glazed green-spotted yellow slipware
  • Glazed yellow and brown slipware
  • Glazed, decorated slipware using:
    • White slip
    • Black slip
    • Red slip
    • Brown slip
    • Green slip
  • Unglazed red ware
  • Unglazed slipware
  • Unglazed, decorated slipware using:
    • White slip
    • Black slip
    • Red slip
    • Brown slip
    • Blue slip
    • Green slip
    • Gray slip

 

Red Earthenware with manganese specks:

  • Glazed red ware with dark brown-black spots and streaks
  • Glazed brown ware with dark brown-black spots and streaks

 

Are you interested in learning more?

Historical Archaeology in Wachovia: Excavating Eighteenth-Century Bethabara and Moravian Pottery by Stanley South. http://www.worldcat.org/oclc/757578598

The Moravian Potters in North Carolina by John Bivins, Jr. http://www.worldcat.org/oclc/593503079 

Eighteenth Century Earthenware from North Carolina: The Moravian Tradition Reconsidered. By Luke Beckerdite and Johanna Brown. Ceramics in America, 2009. http://www.chipstone.org/article.php/449/Ceramics-in-America-2009/Eighteenth-Century-Earthenware-from-North-Carolina:-The-Moravian-Tradition-Reconsidered

 

[1] Nov 28, 1755. This afternoon the mill was run for the first time; the sawmill is not yet ready, and the dam is not finished. The mill was first tried in grinding flint for glazing, – it made a fine powder. Then it was a difficult task to remove the upper mill-stone, clean and recut it.  RNMC V1 149.

[2] Bivins, John Jr. The Moravian Potters in North Carolina. The University of North Carolina Press, Chapel Hill. 1972. 79.

[3] South, Stanley. Historical Archaeology in Wachovia: Excavating Eighteenth-Century Bethabara and Moravian Pottery. Kluwer Academic/Plenum Publishers, New York. 1999. 213-215.