Stoneware Manufacturing Processes
The types of kiln used by the Yorktown potters as well as their techniques of manufacture will not be known until the factory site is located and carefully excavated. Until that time, the Yorktown stonewares raise more questions than they answer. The most important of these is the shape of the kilns and how they were fired. The wares run the gamut from such under-burning that the iron-oxide slip has evolved no further than a zone of bright-red coloring, to overfiring which has turned the slip a deep purple and the body to almost the hardness and color of granite. Do these differences result from a lack of control over entire batches, or do they stem from temperature variations inherent in different parts of the kiln? Mr. Maloney's experiments, made without the use of saggers, have shown that close proximity to the firebox can unexpectedly and dramatically affect the wares.
Thus, one mug of his first test series was placed much closer to the direct heat than were the rest, with the result that it emerged with an overall dark, highly glossed surface somewhat reminiscent of Burslem brown stoneware.
The only real evidence of the Yorktown manufacturing process comes from the many sagger fragments that have been found around the town. The largest single assemblage was discovered on the Swan Tavern site, but another group of large pieces was recovered from beneath the Archer Cottage at the foot of the colonial roadway leading down to the river frontage. In neither instance is it likely that the sherds were serving any practical purpose, and so it is hard to imagine why they would have been taken to these widely distant locations.
The Park Service Yorktown collection includes sections through three saggers of different sizes, one for holding quart tankards (fig. 12), another for pint mugs, and a third which might have served for the bowls, the last being 5¾ inches in height and having an interior base diameter of approximately 8 inches, with walls ½ inch thick and side apertures 5½ inches apart.[260] These apertures are pear shaped and are common to all the Yorktown saggers, as they are also to the examples excavated at Bankside in London.[261] The tankard saggers have three such holes plus a vertical slit which extends from the top to the bottom to house the handles, but it is not known whether the wide and shallow example described above would have possessed this feature. If this example was intended only for bowls, a slot would not have been needed and an extra aperture probably would have been substituted: but were it also used for pipkins, a handle opening would have been essential. The purpose of the pear-shaped apertures was to enable the salt fumes to percolate freely around the vessels being fired. For the same reason sagger lids sometimes were jacked up on small pads of clay, or the sagger rim scooped out here and there to let the fumes enter from the top. A careful examination of some of the Yorktown vessels shows that those closest to the salting holes received excessive fuming through the sagger apertures, the outlines of which were transferred to the pots in patches or stripes of heavy greenish mottling.
Figure 15.—Yellow lead-glazed earthenware creampan of local Tidewater manufacture, probably dating from the second quarter of the 18th century. Found in Williamsburg. Rim diameter 34.29 centimeters.
Other kiln furniture found in Yorktown includes fragments of sagger lids having an average thickness of ¾ of an inch and various lumps of clay which served as kiln pads and props.[262] Without knowing the type of kilns used it is impossible to determine how the saggers were employed. It is obvious, however, that they prevented the pots from sticking together in the kiln, from being dripped upon by the fusing brickwork of the roof, and from becoming repositories for the salt as it was thrown or poured into the kiln. But, as Mr. Maloney demonstrates daily, it is perfectly possible to make good stoneware without saggers, though wasters will accrue from the mishaps just described. If a single-level "crawl-in" or "groundhog" type kiln is used, the number of pots discarded as wasters is more than offset by the space saved through not using saggers. It can be argued, therefore, that Rogers' kiln was of a type in which the saggers served the additional function of allowing the pots to be stacked one on top of the other instead of being spread over a wide flat area, in which case it is possible that the kiln or kilns were of the beehive variety.[263]
Figure 16.—Lead-glazed earthenware bowl of typical Yorktown type, probably dating from the second quarter of the 18th century. Found in Williamsburg. Rim diameter 18.95 centimeters.
The manufacture of stoneware requires only one firing at a temperature of about 2300° F., and it takes Mr. Maloney approximately 13 hours to burn them, although at Yorktown the use of saggers may have necessitated prolonged "soaking" of up to 24 hours or more. The salt was thrown in at the peak temperature and repeated at least twice at intervals of about a half hour. When the fire was extinguished the kiln would have been allowed to cool for up to two days and two nights before it could be unloaded. Mr. Maloney has stated that his stoneware kiln, which he considers small, takes approximately three hours to load. Thus, if the Yorktown factory worked at full capacity, it probably would have been possible to fire each kiln once a week. But, not knowing how many workmen were engaged in the operation, we would be unwise even to guess at the size of its output. The listing of stoneware and coarse earthenware included in Rogers' inventory is not particularly large, although £5 worth of "crackt" stoneware might have represented a considerable quantity of "seconds" or wasters when one considers that 26 dozen good quart mugs were worth only 4 shillings more.
Pint mugs are the most commonly found stoneware relics of the Yorktown factory. Following the "26 doz. qt Mugs £5.4.," a value of 4d. per mug, we find "60 doz pt Do 7.10."[264] A stock of 60 dozen would be reasonable because, as Mr. Maloney has stated, a good potter can throw approximately 12 dozen a day.
Figure 17.—A pair of brown lead-glazed local earthenware funnels, paralleled by a fragment from Yorktown, discarded in the mid-18th century. Found in Williamsburg. Rim diameters: left, 18.25 centimeters; right, 18.42 centimeters.
Before leaving the evidence of the inventory it should be noted that the vessels which we usually term storage jars are probably synonymous with Rogers' "9 large Cream Potts 4/6"; but where are the large stone bottles? The "4 doz small stone bottles 6/" were likely to have been of quart capacity. We can only suppose that the large bottles were not included in the batches fired just before Rogers died and that, consequently, he had none in stock.