Center For Transportation Research

Knox County, Tennessee



Knoxville, Tennessee 40KN 201

LABORATORY PROCEDURES AND ARTIFACT ANALYSIS

Laboratory methods for the analysis of materials recovered during the Intensive Phase I survey at 40KN201 consisted of:
  • The analysis of ceramics by type, form, age, and socioeconomic indicators;
  • The analysis of container glass by the same criteria as above, where possible;
  • The analysis of window glass by color, thickness, and probable age;
  • The analysis of other architectural artifacts by appropriate means; and
  • The analysis of all remaining categories of artifacts by South's (1977) historic artifact groups, modified appropriately.

    Ceramics

    Ceramics are the most important class of artifact commonly found on historic sites because vessel form, paste, glaze, and decoration changes have been well recorded through time. Ceramics are broadly grouped into two major categories, coarse and refined, based on the amount of refining of the clay in the manufacturing process. Ceramics are also grouped by the degree of vitrification the clay has undergone in firing. The lowest temperature wares are called earthenware and are not vitrified. Earthenwares are porous and will not hold water unless glazed. Most refined tablewares are a type of earthenware, such as pearlware or whiteware. Unrefined earthenwares such as the yellow wares, redwares, and terracotta are often coarse utility vessels. The next higher temperature wares are the stonewares, which are partially vitrified and will hold water without a glaze. Ironstone and semiporcelain are refined stonewares while coarse stonewares include salt glazed, Bristol glazed, and Albany slip glazed crockery. The highest temperature ceramics are the porcelains. Porcelain is fully vitrified and in the highly refined specimens the glaze is indistinguishable from the paste of the body.

    Refined Ceramics

    Creamware
    Creamware is a refined earthenware invented by Josiah Wedgwood in 1762 as a cheaper substitute for both Chinese porcelain and white salt-glazed stoneware (Noel-Hume 1970). It consists of a buff to creamy white clay body covered with a clear lead glaze and after about 1800 is rarely decorated, except for annular banding. Creamware was produced until around 1830, when it became indistinguishable from whiteware (Miller 1980).

    Pearlware
    Pearlware was invented by Josiah Wedgwood in the 1770s. This is a refined earthenware with a creamy white body covered with a clear lead glaze containing cobalt. It was produced in an attempt to produce a cheap substitute for Chinese porcelain. The cobalt in the glaze makes the cream colored body appear whiter while the glaze itself takes on a distinct bluish cast, using exactly the same principle as adding bluing to white laundry items. Pearlware was being manufactured all over Great Britain by 1790 and continued in manufacture until its gradual replacement by whiteware over the period from circa 1825-1835 (Miller 1980).

    Whiteware
    Whiteware was not invented per se but rather seems to have evolved from pearlware and creamware over time. The clay body is closer to being white than either creamware or pearlware although there is evidence that manufacturers sometimes put cobalt in the clay rather than the glaze to achieve this effect (Miller 1991). Potters continued to use cobalt in the glaze as well, resulting in some confusion for archaeologists when presented with blue-tinted sherds of pottery. Whiteware glazes contained lead in some degree for most of the nineteenth century but the lead was gradually replaced with a clear felspathic glaze which is still used (Miller 1991). Whitewares first appear in the 1820s and by the late 1830s were ubiquitous in American households.

    Transitional Wares
    Transitional wares are a category of convenience rather than a true ceramic type. In this analysis, all refined earthenwares which show characteristic traits of both pearlware and whiteware are classified as transitional wares and are given a date range corresponding with the period during which whiteware gradually superseded pearlware as the common table ceramic, 1820-1835. Historical archaeologists have long attempted to find an easy way to distinguish late pearlware from early whiteware (Noel-Hume 1970; Price 1979). The most common method is to look for blue puddling of the glaze combined with a refined thinness of the ceramic body and the use of certain colors for underglaze enameling (Price 1979:14-15). Unfortunately, this method can produce erroneous results. The slow whitening of pearlware and the vestigial bluing of whiteware, combined with the various manufacturers use of the term "pearl" to refer to their wares long after the disappearance of what archaeologists call pearlware, make a critical determination of ware type in some cases almost impossible for the years between 1820 and 1835. To make matters worse for those who use glaze tint as a criterion, there was a resurgence in the popularity of blue tinted glazes on whiteware produced for the provincial English and American markets in the 1840s (Miller 1980:17-18). Fortunately, these later blue tinted whitewares are easily distinguished from the transitional period wares by their thickness and decoration. The use of a transitional ware category in the calculation of Mean Ceramic Dates (South 1977) will tend to even out the discrepancies that would appear with the use of arbitrary classification of these wares as either pearlware or whiteware. The root of the debate over the determination of ware type can be reduced to one concern - chronology. The transitional wares category addresses this concern by providing a tighter date range for certain artifacts.

    It is interesting
    that the potters who manufactured these wares and the archaeologists who classify them generally use different groupings. In the eighteenth century, potters distinguished between creamware and pearlware and they continued to do so into the nineteenth century. However, the people who made whiteware did not distinguish between whiteware and creamware, which had been gradually getting whiter of body through its long existence. In fact, the two wares are a single evolutionary lineage (Miller 1980). Paste colors and decoration types allow archaeologists to date all these wares with relative ease. The importance to archaeologists of the creamware/pearlware/ whiteware evolution in which creamware and whiteware are actually the same is primarily a matter of socioeconomics, as Miller has pointed out with his tables of "C.C. values" for various nineteenth century ceramics (Miller 1980, 1991). After the invention of pearlware, pearlware was a semi-luxury item while creamware was not. According to the manufacturers' price lists, this held true as creamware became whiteware, with the price of pearlware gradually falling to match. By 1830, the type of ware was not relevant as the price of the ware was based solely on the level of decoration (Miller 1980, 1991).

    Ironstone
    Ironstone was invented in England in 1813 by James Mason (Godden 1964:163) but did not begin to become popular in this country until the 1850s or later. Ironstone is a refined white-bodied stoneware with a white feldspathic glaze and is partially vitrified. It was heavier and harder than earthenware and as a result was more durable and more expensive. One hindrance to its popularity in this country was the fact that early ironstone was not colorfully decorated, as no technique of the time but blue transfer-printing could withstand the heat of the firing. During the mid-nineteenth century, however, various sanitation campaigns inspired the popularity of plain white dishes and simultaneously the ironstone industries of East Liverpool, Ohio arose; a combination which ensured the long-term popularity of semivitrified wares in this country. From the 1870s to the 1920s, ironstone was king of the table. Unfortunately, it is sometimes difficult to distinguish between ironstone and whiteware when examining sherds from archaeological contexts.

    Porcelain
    Chinese porcelain was quite fashionable for the wealthy classes in the late eighteenth and early nineteenth centuries. It is a hard-paste porcelain, so called because it is completely vitrified to the point where the glaze is indistinguishable from the body of a broken piece. It is bluish-white in color and, if thin enough, is translucent. The Spode Company of England, while trying to duplicate the properties of porcelain and firing at a lower temperature, invented bone china in 1800 by mixing calcined animal bone and ground flint with white kaolin clays. Bone china is a soft-paste porcelain, so called because it is slightly porous and will stain if broken and the glaze is distinct from the body. Relaxation of the high tariffs against Chinese porcelain by the British in the first quarter of the nineteenth century resulted in a surplus causing the market for Chinese porcelain to collapse, as it was no longer expensive (Noel-Hume 1970). Bone china, however, remains expensive to the present day.

    Coarse Ceramics

    As compared to the refined ceramics, coarse utilitarian wares were usually of local manufacture. In some parts of the southern United States, the local manufacture of utilitarian stoneware persists to the present day. It has become more of a folk art curiosity than a necessity of life (Burrison 1983; Greer 1981; Ketchum 1991; Zug 1986).

    Redware This is a coarse earthenware which has been manufactured for centuries. The clay body is reddish-brown to buff colored and is usually covered with a lead glaze which may be clear or colored with various metallic oxides (copper produces greens and blues, manganese produces a rich brown, and iron produces a deep blackish brown). The manufacture of unglazed redware in the form of flowerpots continues today. Redwares were primarily utility wares, such as crocks and beanpots, but refined redware pitchers and other table pieces were made as well. Redware was slowly supplanted by stoneware in most of Tennessee beginning in the 1820s and was almost gone by the 1840s but lead glazed utilitarian redware continued to be made in upper East Tennessee until the 1880s (Smith and Rogers 1979).

    Yellow Ware This is a buff-bodied coarse earthenware with a clear lead or feldspathic glaze. It was first produced in 1828 in East Liverpool, Ohio. It was also produced at an early date in New Jersey and production later spread from New England to the Mississippi River Valley, with concentrations in Ohio and Illinois. Pfalzgraff of Pennsylvania produced a yellow glazed stoneware which was not a true yellow ware in the late nineteenth-early twentieth century (Lehner 1987). Yellow ware was almost always a utilitarian ware, with bowls and pitchers being the most common forms. It was often given a form of annular decoration, with bands of colored slip placed horizontally on the vessel.

    Stoneware Stoneware production in Tennessee started in the first quarter of the nineteenth century. It was harder, more durable, more watertight, and most of all less toxic than lead glazed redware and it supplanted redware for food storage and preservation purposes by the second quarter of the nineteenth century. Salt glazing is the earliest surface treatment of stoneware found in Tennessee. It was invented in the fifteenth century in Germany. It is produced by throwing common salt (sodium chloride) into a kiln full of white-hot stoneware. The salt vaporizes and the sodium combines with the silica in the clay and produces a hard heat resistant film of sodium silicate glass on all exposed surfaces of the vessels (Zug 1986:172). The chlorine combines with available hydrogen and exits the kiln through the chimney in the form of hydrochloric acid vapor. After the Civil War and reconstruction era, local potters had access to "store-bought" glaze in the form of Albany slip, a brown siliceous clay from the Hudson River near Albany, New York, which vitrifies at stoneware firing temperatures. Albany slip appears in Tennessee in the late 1870s (Smith and Rogers 1979). Another "store-bought" glaze was Bristol glaze, an opaque white feldspathic/zinc oxide slip which was invented in Bristol, England during the 1860s and appears in Tennessee around 1890. The bright white surface of a Bristol glazed vessel seems to have appeared more sanitary than the older brown salt glazed vessels, a point which was of social concern in the late nineteenth century. Bristol glaze and Albany slip often appear together on factory-made stonewares dating from 1890-1930, in the form of the familiar brown and white crockery which fills antique stores.

    A list of the ceramic dates used for the analysis of artifacts from site 40KN201 is found in Table 1. In some cases, these dates have been modified from their original sources in order to correspond with the later time ranges encountered at the site. Modified dates are designated by the letter "m" after the source number.

    Glass

    Flat Glass
    Glass falls into two basic groups: curved and flat. Flat glass is almost always window glass and is placed in the architectural artifacts group. Curved glass is usually container or table glass; vessels such as bottles, jars, bowls, drinking glasses, and plates. Flat glass of the eighteenth and nineteenth centuries, assuming that it is in fact window glass, can be roughly dated by means of various formulae. Moir's formula (Moir 1987) perhaps provides the best results in the Southeastern United States. The formula is:

    This formula provides a date in actual calendar years which seems to be accurate to within five years in Tennessee. Window glass becomes gradually thicker through time, as methods of manufacture and raw materials improved (Roenke 1978). Most nineteenth century window glass was made by the cylinder method, wherein a worker took a large blob of glass on a blowpipe and slowly blew a free-hanging cylinder while leaning over the edge of an elevated platform. These cylinders could be as large as 18 inches in diameter and 8 to 10 feet long. After cooling slightly, the cylinders were split lengthwise and flattened out. When they had cooled completely they were cut into panes. Throughout the nineteenth century the formulae for glassmaking improved slowly but consistently, resulting in thicker glass (Roenke 1978). After the advent of float glass in the early twentieth century, window glass thickness is no longer a reliable dating method.

    Container Glass
    Container glass is a much more difficult item to analyze. Method of manufacture is not easy to determine unless basal sherds and lip sherds are present and if the sherds are very small (as is usually the case ) vessel form is difficult to determine as well. Curved glass was sorted by color, vessel form, and to a small extent thickness. Container glass is not common on rural historic sites of the early nineteenth century in Tennessee. Only after the invention of various machines for the semiautomatic production of jars and bottles after 1870 does glass become a common artifact in this area, mostly in the form of panel bottles and canning jars. Early nineteenth century forms of container glass that are found with some frequency in Tennessee are mostly wine and liquor containers. Freeblown and moldblown dark olive green bottle fragments are typical of sites predating 1830 (Jones and Sullivan 1985) while light green or amber moldblown pictorial or "historical" flasks are present from around 1825 to around 1840 (McKearin and McKearin 1941; Munsey 1970). Clear glass with a blue-green tint appears in freeblown and moldblown bottles and jars in the mid-1840s and quickly becomes the most common container glass type. Almost all bottles made prior to the invention of the snap case around 1850 have pontil marks on the base where the bottle was held on a rod with a little blob of molten glass while the neck was finished (Jones and Sullivan 1985). By 1860, empontiled bottles were rare. The invention of moveable plates in flat molds after the Civil War resulted in the panel bottle, in which medicinal products of all descriptions were sold until the pure food and drug act of 1906 put the makers of most patent medicines out of business (Munsey 1970). Panel bottles are important artifacts because they sometimes have the name and address of local druggists or of patent medicine vendors embossed on the sides. With this information it is possible to speculate on the illnesses, real and imaginary, which plagued the former inhabitants of sites. Panel bottles are also good dating artifacts, if the druggist mentioned on the bottle can be located in the documentary record. Canning jars were invented in the 1850s but did not become common in Tennessee until the 1890s, as they were more expensive and more fragile than locally made stoneware preserve jars. Only after 1900 did glass jars begin to replace stoneware in popularity in the South (Burrison 1983).

    The most reliable indicator for dating container glass manufactured after the Civil War is the treatment of the lip, if the vessel is a bottle. Bottle lips were laid on by hand until the mid-1820s, when the lipping tool was introduced (Jones and Sullivan 1985:43). Fully mold formed lips appear in the 1880s, although they were not common until the 1890s. With the invention of the fully automatic Owens machine for bottle and jar manufacture in 1903, fully machine-made containers become ubiquitous (Jones and Sullivan 1985). Glass color can also be used as a relative dating tool. Glass of the mid nineteenth century often has a blue-green tint. As consumer pressures for pure food products increased in the later years of the century, the demand for cheap nonleaded truly colorless glass increased as well. Beginning about 1886, manganese dioxide was used to produce a colorless glass. An unplanned effect of this process is the fact that manganese-clarified glass will turn purple with prolonged exposure to the ultraviolet light from the sun, resulting in what is popularly called amethyst glass. With the advent of World War I, the supplies of manganese (which came from Germany) were cut off. After about 1915, selenium was used as the clarifying agent, resulting in a slightly yellowish glass. Arsenic was used from around 1930 to the present. (Jones and Sullivan 1985).

    Pressed Glass
    Pressed glass tablewares are not easily dated, since patterns were produced over long periods of time. The early (1820-1850) "lacy" pressed glass is not commonly found in Tennessee. As with container glass, pressed glass only becomes cheap and popular after the Civil War (Lee 1931; McKearin and McKearin 1941).

    Metal

    Non-Nail Metal
    Metal artifacts are sorted first into groups listed in South (1977) and then by material of manufacture and function. Explanation and interpretation of non-nail metal artifacts is done on a group- or artifact-specific level.

    Nails
    Prior to the invention of the nail cutting machine in about 1790, all nails were hand wrought in sizes and head shapes suited to their intended purpose. After the invention of machine cut nails, nail sizes were standardized according to the pennyweight system, which was later carried over to wire nails. Cut nails were not perfected until around 1830, although their use was quickly overtaking that of wrought nails for all but the most specialized functions in Tennessee by the 1820s. After the introduction of fully machine-cut nails, wrought nails quickly disappear from the archaeological record. Cut nails are still produced for certain purposes, such as rough flooring and masonry work. Drawn wire nails were in use for furniture manufacture in England by the second quarter of the nineteenth century but the machinery for their manufacture was not imported to this country until the last quarter of the century. In Tennessee, the replacement of cut nails with wire nails for general construction purposes was a gradual process, occurring in the 1880s and 1890s; thus it is common to find both kinds of nails on sites of the later nineteenth and early twentieth centuries.

    Other Materials

    Items such as buttons, beads, tobacco pipes, et cetera were also collected. Analysis of these objects varies.

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