Magazine Antiques: Slipups: Mocha ware at the Shelburne Museum

Mocha ware, with its brightly patterned surfaces and surprisingly modern decoration, has attracted the attention of collectors for many years. (1) Recently, research on the origins of its kaleidoscopic designs has resulted in the publication of important books and articles by Sumpter Priddy, Donald Carpentier, and Jonathan Rickard. (2) In addition, the Shelburne Museum in Shelburne, Vermont, has recently reinstalled its 230 pieces of mocha ware, the largest public collection in the world. The two-year project enabled the museum staff to closely evaluate our holdings, actively acquire important pieces, and most important compare, contrast, and come to our own conclusions regarding the execution of the remarkable surfaces of mocha ware. This article summarizes some of our observations and discoveries. (3)

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A product of the industrial revolution, English mocha ware was mass produced for commercial use in taverns as well as for domestic consumption by the working classes in British, American, and continental markets from the late eighteenth century until the early twentieth century. Although the technology used to manufacture mocha ware was state-of-the-art at the time, the equipment used to produce it lacked the precision and uniformity commonly associated with the automated assembly lines of today. Moreover, the limitations of the available technologies required a high level of handwork on the part of decorators, which, in turn, increased the potential for irregularities. In short, the strikingly colored slip surfaces of mocha ware often reveal the presence of the human hand within the industrial process. Practically invisible or blatantly obvious, these so-called slipups made centuries ago survive today beneath vitrified coats of clear overglaze and provide snapshots of the innovative and ingenious decorative techniques employed. By studying the fanciful surfaces on a select group of mocha ware objects in the Shelburne Museum's collection, we have obtained invaluable clues for deciphering the methods used in their production.

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Inexpensive and easily made, slip--a mixture of clay and water--is a free-flowing and versatile decorating medium that has been used to ornament the porous surfaces of ceramic vessels for millennia. Slip is also fast drying and highly absorbent, making it efficient but unforgiving of human error. Once made, accidents are virtually indelible and can only be corrected by complete removal of the affected surface. In spite of the disadvantages of slip, British manufacturers successfully exploited its versatility and adroitly adapted its ephemeral fluidity to the high volume industrial production of mocha ware. However, both the integrity of the materials and the training of the workforce were crucial to successful mocha ware decoration. If the quality of either was compromised, the resulting decoration suffered.

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As they were competing for the same American, European, and domestic markets, eighteenth and early nineteenth-century Staffordshire potteries emphasized quantity. The economic livelihood of mocha ware decorators depended on their output measured by the tally of their daily production of "good from oven" objects--those that survived the kiln firing in pristine condition. (4) In this fast-paced industrial setting, the decorators focused on stocking the kilns with as many pieces of their work as possible, which ultimately often compromised the finished product. Imperfect surfaces made their way into the market because they were sold at discounted prices as second- or third-grade quality objects.

As demand for ceramic goods increased during the eighteenth and first half of the nineteenth centuries, English potteries--always hotbeds of experimentation--developed and adopted new methods, equipment, and materials to improve their production. Two important innovations for slip decoration were the rose-and-crown engine-turning lathe and the three-chambered slip cup.

During the late 1760s, Josiah Wedgwood (1730-1795) introduced the so-called rose-and-crown engine-turning lathe to the pottery industry. Originally used to produce scored decoration on metalwork, this engine-turning lathe was similar in principle to its counterpart for wood, except that its rotational movement was governed by two types of cams. When used in conjunction with custom-made stationary blades, the peaks and valleys of the sprocket-shaped edge cam (or rose cam) produced horizontally oriented decoration like reeding, fluting, basket weave, and rhythmic patterns of incised squares and rectangles. The end (or crown) cam moved the axle of the lathe back and forth longitudinally, producing undulating patterns of curves and arches that moved vertically over the surface of the upright vessel. (5)

Inspired by the rose-and-crown engine-turning lathe he encountered on a visit to the Soho metal manufactory of Matthew Boulton (1728-1809) in Birmingham, in 1763, Wedgwood originally adapted the new technology to cut reeds, flutes, and shallow-incised decoration into the bodies of his red stoneware, black basalt, and multicolored jasper ware. The subsequent application of the engine-turning lathe to slip decoration resulted in the mechanization of two age-old slip techniques--inlay and sgraffito.

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An example of inlaid engine-turned decoration is the shallow black-and-white checked or diced pattern seen on a quart mug of about 1800 in the Shelburne collection (see Pl. I, second shelf down, right, and Pl. V). This striking design was first cut into the body when it was leather-hard using a set of metal blades with precisely spaced teeth. Guided by the rose cam, the mug's body came into contact with the teeth at regular intervals, creating the perfectly aligned repeating pattern. Next, the entire area of incised decoration was covered with a layer of black slip. Then, using a flat blade on the lathe, the slip was scraped away, exposing the white earthenware body inlaid with the black checked pattern. Although not obvious in the photograph, the resulting peaks and valleys across the surface are evident to the touch. The misshapen squares and rectangles, the fringed edges and sides, and the overlapping corners (see Pl. V) were byproducts of the turning process and the probable inattentiveness of the lathe operator, or turner. Perhaps distracted by the fast tempo of the hectic work environment and the desire to increase his output, the turner speedily removed just enough of the black slip to reveal the individual blocks, leaving remnants of the slip behind in his haste.

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The sgraffito (from the Italian for scratched) fluting on a coffeepot recently acquired by Shelburne (see Pl. I, second shelf down, center, and Pl. IV) was achieved by first coating the entire exterior of the vessel with a buttery-colored slip and then using custom-made blades to create the tall narrow flutes by cutting through the light yellow slip to expose the white earthenware body beneath. The brick red slip stripes mimic the common industry practice of layering multiple colors of slip over one another and using blades set at varying depths to expose the contrasting colors in complicated offset designs. The stripes on the coffeepot, however, were not achieved by turning. Instead, they were applied individually by hand, as is revealed by the inconsistencies in the opacity of the quivering stripes and the rounded top and bottom edges that overlap the right-angled corners of the scratched flutes. The stripes were painted on after the handle and spout were attached to the body judging by the small red dot on the lower acanthus terminal (see Pl. IV) of the handle, which was perhaps accidentally laid down as the decorator attempted to steady his hand to apply the stripe directly above the leaf.

If unable to afford an expensive rose-and-crown engine-turning lathe, smaller potteries could adapt rouletting wheels to produce delicate linear and intricate geometric patterns on their mocha ware (see Pls. VI, VII). A tool that already existed for decorating ceramics, a rouletting wheel is similar to a pie crimper in both appearance and function. Examples were made of metal, wood, or clay, with the edge of the roulette disk decorated with simple designs that are rolled onto the earthenware surface. This tool was first employed by mocha ware manufacturers to create horizontal bands that served as borders between colored slip fields. The thin lines of incised decoration were impressed into the leather-hard body by the rouletting wheel while the vessel was attached to a simple wood-turning lathe or a less expensive rose-cam lathe known as a dicing lathe. Next, while slowly rotating the vessel on the lathe, the decorator applied a coat of colored slip over the rouletted areas, filling the interstices of the impressed patterns. The excess slip was then removed with a flat blade, leaving the rouletted pattern inlaid with colored slip. This process lacked the stability of the stationary blades and the control of the engine-turning lathe's mechanized movement. Shifts in the decorator's weight and wobbly rouletting wheels produced uneven impressions in the vessel's surface that were only perceptible after the excess slip was removed, exposing incomplete decoration (see Pl. VI). Sometimes the decoration was misaligned, possibly because the decorator was overworked or distracted (see Pl. VII).

The introduction of a specialized decorating tool known as a three-chambered slip cup spawned an entire subcategory of mocha ware decoration, namely cat's-eye, common cable (or earthworm), and twig decoration. As implied by its name, the three-chambered slip cup has three distinct compartments to hold colored slip, each outfitted with a nozzle (often a goose quill). When the cup is tilted down, the three colors of slip pour out, producing a tricolor dot resembling a cat's-eye marble (see Pl. IX). (6)

The orange, blue, and white colors of the large cat's-eyes on Shelburne's barrel-shaped jug (see Pl. I, bottom shelf, right) are each differentiated. However, they exhibit two flaws commonly associated with this type of decoration. First, the white line (see Pl. IX) around the periphery of each cat's-eye indicates that the white slip was over-saturated with water, causing it to run and become more transparent and allowing the field of olive green slip below to show through. Secondly, the presence of a smaller identical cat's-eye in the white wedge of each larger cat's-eye resulted from excess drips off the spouts of the three-chambered cup.

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The two-color cat's-eyes (see Pl. X) on a cream jug in the Shelburne Museum collection (see Pl. I, top shelf, left) were probably caused by either a tool malfunction or error on the part of the decorator, (7) because traces of another slip color in the cat's-eyes confirm that three were intended. Dried slip often accumulated in the passageway of the goose quill nozzles, blocking the flow of the liquid clay, which may have been the case here. Equally likely, one of the chambers may have run dry, and, in the interest of time, the decorator continued to exhaust the remaining slip in the other two chambers before stopping to replenish his supply.

Whether meandering or looped, the type of mocha ware decoration known as common cable was made by simply overlapping a series of cat's-eyes, one on top of the other: A large cat's-eye (see Pl. VIII) marks the beginning and ending point of this type of design on a water pitcher of about 1830 in the Shelburne Museum's collection (see Pl. I, bottom shelf, left). The size of this initial cat's-eye also acted as a gauge to help the decorator calibrate the size of the continuous decoration by raising or lowering the height of the slip cup. By lowering it--that is, holding it closer to the vessel being decorated--the decorator created a smaller pattern.

Among the oldest and most common types of surface decoration used to camouflage and enhance the humble materials often used for architectural elements, furniture, and pottery were faux finishes. Thin layers of variegated slip gave pallid earthenware surfaces the illusion of solid stone. The asymmetric mineral inclusions characteristic of semiprecious stones such as marble, agate, granite, and porphyry inspired the colorful patterns of three distinct types of mocha ware decoration: marbleized, dendritic, and so-called tesselated inlay. Marbleized decoration--so-called because of its resemblance to the striated veins common in marble--is believed by many scholars to have originated in northern Italy during the late sixteenth and early seventeenth centuries. (8) The writhing marbleized swirls of brick red, black, and white slip found at the bottom of the well of the pearlware plate of about 1790 in Plate III, newly acquired by the museum, were created by joggling--a process that relied on the viscous compatibility of the variegated slips and the movement provided by centrifugal force. (9) The turbulent veins were created by twisting and turning the plate by hand while the slip was still wet. The path of the streak of white slip that starts at the top of the plate well charts the direction of the movement. The centrifugal force also caused the slip field to spread out over a large area of the plate. Evidence that excess slip was subsequently removed can be seen where the outer edge of the swirling mass is abruptly cut off at the lower left, indicating that the decoration originally extended further up the curved cavetto of the plate.

The treelike mineral inclusions found in moss agate--a semiprecious stone commonly used in stylish jewelry during the late eighteenth and early nineteenth centuries (see Pl. XI)--inspired the silhouetted dendrites that decorate some mocha ware and provide an example of creative cross-pollination between two independent worlds of fashion. The branching dendrites found in moss agate were created by mineral deposits of managanese and iron trapped in fissures within the rock. Indigenous to Arabia, moss agate was exported in great quantities from the port of Mocha (al-Muhka in Yemen) to London jewelers, giving it the nickname "mocha stone," from which the term mocha ware is derived.

To achieve this decoration, potteries concocted so-called mocha teas, which were acidic solutions typically composed of vinegar, hops, tansy (an aromatic herb), and urine and colored by either tobacco juice or printer's ink. A paintbrush was used to dab the tea onto a ground of dried slip; the interaction between the acidic mocha tea and the surface of alkaline slip was similar to that of oil on water, with the result that the brown tea solution ramified, or bloomed, into dendrites. Like secret family food recipes, the ingredients of mocha tea concoctions varied from pottery to pottery, and results ranged from vivid, well-articulated dendrites (see Pl. XIV) to blurred faint apparitions (see Pl. XIII). (10) Free-floating horizontal dendrites, such as those on the quart mug in Plate XIII (see also Pl. I, third shelf from the top, left), are sometimes referred to as seaweed decoration. The faint, runny appearance of those on the mug most likely resulted from an oversaturated mocha tea solution diluting the coloring agent. The darker pools of coloring agent in the lower half of the seaweed indicate that the mug was turned upright from its side after the tea was applied, and gravity pulled the heavier coloring agent downwards.

Gravity also played an important role in the production of the decoration on the bowl of about 1810 in Plate XIV (see also Pl. I, bottom shelf, center). (11) With the bowl held upside down, the tea solution was applied with a loaded brush and flowed downward, the solution expanding randomly as it crossed over the alternating narrow strips of exposed earthenware and brown slip before branching out over the wide orange field of slip.

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The so-called tesselated inlay decoration on a recently acquired teapot of about 1800 (see Pl. I, top shelf, center) represents the third and final type of faux-stone mocha ware in the museum's collection. The teapot's specked and flecked surface was most likely inspired by the metallic oxide surfaces of Wedgwood's granite and porphyry wares dating from the 1770s. (12) Two types of igneous rock, granite and porphyry, are both embedded with small crystals of quartz, feldspar, and mica. (13) To create the illusion on Shelburne's mocha ware teapot, small particles of dried, variegated wedged clay were thoroughly mixed into a larger batch of blue clay. The blended clay was then formed into a brick, a thin slice of which was inlaid into a shallow recessed channel around the body of the teapot and adhered with wet slip. The body of the teapot (without handle and spout) was then turned smooth on a lathe. The area of loss high-lighted in Plate XII illustrates the intrinsic flaw in tessellated inlay decoration: particles were apt to become dislodged as the thin strip of mixed clay was bent around the oval teapot. (14)

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Without a historically accurate term, the variegated slip decoration on the orange pint mug in Plate II (see also Pl. I, top shelf, right) is often referred to by collectors as tobacco leaf, balloon, feather, or fan ornament. The shape and diameter of this type of motif is dependent on the size and curvature of the vessel being decorated, ranging from tall narrow feathers, or fans, on half-pint and pint mugs to large circular balloons, commonly found on coffeepots. For consistency, this article will refer to the decoration as fan.

Fan decoration was achieved by dipping the sides of a vessel into a shallow dish filled with variegated slip. Because the central portion of the dipped area was the initial point of contact between the porous and liquid surfaces, the middle of the fan accumulated a thicker coating of slip. After the process was repeated three or four times to create the corresponding number of fans, the vessel was turned upright and allowed to dry. Because the outer edges of the fans were coated with a thinner layer of slip, they were the first to dry; still wet and fluid, the more thickly coated centers of the fans slid down the sides of the vessel due to gravity, and created the characteristic stem.

The noticeable discrepancies in the size, shape, and overall pattern of the fans on the pint mug pictured in Plate II illustrate the inherent variability associated with this type of decoration and provide a timeline of manufacture. (15) The repetitive process of dipping the sides of the mug into the pool distorted the surface of the slip, which expanded as the mug was pushed into the pool and contracted as it was removed. With each successive dunking, the rays of the fans grew larger and less distinct. Thus, the stripes of the fan visible in Plate II are crisper and smaller than the more amorphous and wider stripes of the fans on the other side (see Pl. I, top shelf, right).

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The technical inconsistencies described here as slipups provide visual documentation of the mechanized and hand-manufacturing processes involved in mocha ware decoration. The predictability of mass production is always accompanied by the possibility of human inaccuracy. The resulting idiosyncrasies make each piece of mocha ware truly unique and enhance our understanding and appreciation of these remarkable objects.

The author would like to thank Jean Burks, curator of decorative arts at the Shelburne Museum for her guidance and assistance throughout this project. The objects included in this article, along with 90 percent of the Shelburne Museum's mocha ware collection, are on permanent display in the museum's primary decorative arts gallery, the recently renovated Variety Unit building. Comprised primarily of mugs, jugs, pepper pots, and bowls, the collection also includes such rare pieces as a plant pot with matching saucer, a mug with its original cover, a covered sugar bowl, and a unique French water cooler.

(1) Known by many names, including banded creamware, mocha ware has been the subject of three articles in this magazine: Robert J. Sim, "Banded Creamware," The Magazine ANTIQUES, vol. 48, no. 2 (August 1945), pp. 82-83; Susan Van Rensselaer, "Banded Creamware," ibid., vol. 90, no. 3 (September 1966), pp. 337-341; and Jonathan Rickard, "Mocha ware: Slip-decorated refined earthenware," ibid., vol. 144, no. 2 (August 1993), pp. 182-189.

(2) Sumpter Priddy, American Fancy: Exuberance in the Arts, 1790-1840 (Chipstone Foundation, Milwaukee, Wisconsin, 2004); Donald Carpentier and Jonathan Rickard, "Slip Decoration in the Age of Industrialization," Ceramics in America, 2001, pp. 115-134; and Jonathan Rickard, Mocha and Related Dipped Wares: 1770 to 1939 (University Press of New England, Hanover, New Hampshire, forthcoming fall 2005).

(3) I wish to thank Jonathan Rickard for reviewing the Shelburne Museum's mocha ware collection with Jean Burks, the curator of decorative arts at the museum, and me in the fall of 2004.

(4) For more information on this practice see Frank Burchill and Richard Ross, A History of the Potter's Union (Ceramic and Allied Trades Union, Hanley, Staffordshire, 1977), pp. 9-11. Although this source claims that only the potters involved in the production of the objects prior to the biscuit firing were paid according to the "good from oven" wage system, it is generally accepted that all workers, including the decorators, were subject to the pay practice (telephone conversation with Patricia A. Halfpenny, director of museum collections at the Winterthur Museum in Winterthur, Delaware, January 25, 2005).

(5) For the information about the engine-turning lathe and its uses, see Jonathan Rickard and Donald Carpentier, "The Little Engine That Could: Adaptation of the Engine-Turning Lathe in the Pottery Industry," Ceramics in America, 2004, pp. 78-99.

(6) For the information about the three-chambered slip cup and its use, see Carpentier and Rickard, "Slip Decoration in the Age of Industrialization," pp. 126-128.

(7) Conversation with Rickard, September 21, 2004.

(8) Leslie B. Grigsby, English Slip-Decorated Earthenware at Williamsburg (Colonial Williamsburg Foundation, Williamsburg, Virginia, 1993), p. 59.

(9) Michelle Erickson and Robert Hunter, "Dots, Dashes, and Squiggles: Early English Slipware Technology," Ceramics in America, 2001, p. 107.

(10) Margaret E. Turnbull, "Mochaware," Antiques Journal, vol. 29 (August 1974), p. 43.

(11) Rickard, "Mocha ware: Slip-decorated refined earthenware," p. 185. For a demonstration of the application of dendritic decoration, see Donald Carpentier's video Great American Craftsmen: Secrets of Traditional Crafts: Mochaware (Carpentier and Deitz Productions, Eastfield Village, New York, sponsored by Historic Eastfield Foundation, 1996).

(12) For examples of Josiah Wedgwood's granite and porphyry wares, see Robin Reilly, Wedgwood: The New Illustrated Dictionary (Antique Collectors' Club, Woodbridge, Suffolk, 1995), pp. 208, 316, 439, 442.

(13) Materials and Techniques in the Decorative Arts: An Illustrated Dictionary, ed. Lucy Trench (University of Chicago Press, Chicago, 2000), pp. 208, 389.

(14) Jonathan Rickard and Donald Carpentier, "Methods of Slip Decoration on Fine Utilitarian Earthenware," American Ceramic Circle Journal, vol. 10 (1997), p. 41.

(15) Conversation with Rickard, September 21, 2004.

KORY W. ROGERS is an intern in the curatorial department at the Shelburne Museum in Shelbourne, Vermont.