Examination of the archaeological record has shown a remarkable consistency across the pipemaking industry in Britain. Fragmentary muffle evidence supports the evolution of cylindrical forms by the mid seventeenth century. These were open top units requiring some form of temporary cover during the firing. Early muffles appear to have been fairly short until the development of tiered stacking with peripheral shelves and compatible furniture. These developments were made during the eighteenth century. With the increase in height the need for a side opening became apparent. The material from which muffles were constructed, and unique to this application, was a light coloured clay with added organic matter supported and reinforced with prefired pipe stems. One documentary source from 1612, by describing this combination of materials implies the existence of muffles by the early years of the seventeenth century. The coverings for the open tops of muffles appear to have been made from a lightweight thin clay sheet formed over paper or cloth from the mid seventeenth to the late eighteenth century. Early in the nineteenth century this evolved into a composite of prefired stems and thin clay sheets rendered over with material which when subjected to the fire formed a slag or clinker. None of the recovered material is consistent with a fixed dome or cover as implied by the early nineteenth century accounts of Good and Rees. If indeed a muffle was constructed according to the drawing published by Rees it would not be possible to fill the upper part with pipes. The stacking could only proceed to include the shelf below the lintel of the side opening. Clearly then this form is unlikely. The development towards taller muffles may have been induced by a desire for a larger unit able to contain more pipes at one firing. It may also have been linked to product changes. The requirement for furniture would increase pro rata with the size of the chamber and any inability of the product to resist squatting under load. Early pipes, with their short stems, thick walls and intrinsically strong organic forms, were clearly able to withstand a greater load than the larger, thinner bowls which came into vogue early in the eighteenth century. Transverse squatting clearly presented a problem to some eighteenth century pipemakers. Examples of pipes deformed in this way are illustrated from St Albans and Waterford (Figure 45). Reduction in thickness and increase in size would both have imposed limits on load bearing capability. In order to maintain a quantative output some additional support would have been required. It is therefore likely that any product change of this nature would have been accompanied by developments in kiln chamber and furniture design. Contemporary accounts offer little help with this problem. There are no surviving descriptions of British tobacco pipe kilns from the eighteenth century. The changes in pipe styles in the first quarter of the eighteenth century could well have triggered developments in furniture and tiered stacking. Whilst at the present time there is no firm artefactual evidence for peripheral shelving prior to the last quarter of the century, the fine quality and delicacy of eighteenth century pipes in general points towards an earlier date for this development.
The early nineteenth century accounts of Good and Rees illustrate and describe a uniform arrangement of props and buns, in one size only, catering for pipes of a single stem length. This clearly does not reflect the true state of affairs. The furniture assemblages from Lewes and Stamford testify to this. Subsequent accounts (see Chapter 10) tend at best to repeat earlier information and at worst to confuse it with eighteenth century descriptions of the industry in France and Holland. It is not until the 1881 account of McLardy's Manchester kilns that there is any new description of pipe kiln furniture. This account describes the standard made up of clay pillars (props), corresponding in size with the steps in the furnace (peripheral shelves), supporting round clay dishes, or bowls, made of fine (fire?) clay in the shape of "sugar loaves". The 1887 account of the same works refers to the dishes as inverted fire-clay mugs or caps, upon which are laid, all round and close together, the pipes to be burned, the ends of all the stems pointing to the centre. It goes on to record that when ranged round they are covered with very thin sheets of clay backed with paper, as protection. These accounts can be matched to the artefactual evidence for dishes and thin sheets. The recovered dishes are from assemblages with terminal dates of 1870, 1875, 1900, 1919 and 1950. The change from bun to dish must reflect the need for a greater stem support area. This would seem to suggest an increase in stem length. Type 2 saggars were introduced for the same reason. Unfortunately the only certain Type 2 saggars are of too late a date to add significantly to the picture. Type 3 fragments, which seem likely to be from similar saggars, come from two assemblages with terminal dates of 1860 and 1875. The term Churchwarden is associated with a clay pipe with an extra long stem. It is recorded by the Oxford English Dictionary as first appearing in print in this colloquial usage in 1863. Fairholt writing in 1859 does not record the term. He writes of long stemmed pipes that they were reverently termed alderman in the last age, and irreverently yards of clay in the present one (Walker 1976, 143). Yards of clay accords well with the Type 2 saggars which would accommodate a pipe of 32 inches. Although the nature of the evidence is somewhat anecdotal, (the introduction of a new saggar form by 1860, a new term by 1863, and the inverted dish by 1870, all concerning exaggerated stem length) it presents a powerful argument for the introduction of this new fashion early in the second half of the nineteenth century.
Evidence concerning the introduction of open flame kilns occurs in both the archaeological record and documentary sources. Any large assemblage of saggar material implies this form of kiln design. The earliest such assemblage is that from Bristol 12 with a terminal date of 1860. From Boston, saggar fragments were not found in contexts dated before 1860 (Wells 1970, 24). A large and varied group of saggar fragments from Gloucester, Westgate Street, comes from a site only occupied by the pipemaker for a short period between 1871 and 1875 (Peacey 1979, 74). Of these, ground plan evidence was recovered only from Boston where, in company with other stratified artefacts, it suggested conversion from a muffle kiln to open flame retaining its single fire mouth. Later open flame kilns from Limerick, Leith, Broseley and Nantgarw are of multiple fire mouth design. In Manchester, McLardy was using open flame kilns with four fire mouths in 1881 (above pp 285-7) but they were certainly in use before that time. The Ordinance Survey map, surveyed in 1852 and published in 1855, shows two kilns in a yard at Tweedmouth one with three and the other with four fire mouths strongly suggesting open flame practice . Open flame technology did not replace the accepted muffle practice. There is evidence from Newcastle that in 1879 plans were conceived to construct a new factory served by two single fire mouth kilns. Whilst not conclusive, the single fire mouth coupled with rectangular external plan suggests adherence to traditional pipe kiln practice and by implication muffle design. Open flame kilns whether adopted from British potters or continental pipemakers are more likely to be circular, of greater diameter and have multiple fire mouths. Although evidence from Boston and Carlisle suggests conversion of established muffle kilns to open flame, without provision for extra fires, the limitations inherent in such a concept make its new construction at this time unlikely. The same arguments apply to the kiln shown in Daft's planning application submitted in Nottingham in 1880, and Fordham's kiln at Pontefract used until 1908 (Figure 79b). There is documentary evidence to show that the developed muffle kiln was used alongside open flame kilns by the larger manufacturers into the twentieth century. The accounts of McLardy's works quoted above clearly describe both types of kiln in contemporary complementary use.
From as early as 1881 some manufacturers were using downdraft kilns in pursuit of fuel economy and improved consistency in temperature achievement. Such improvements came in addition to rather than in replacement of existing forms. In the latter years of the nineteenth century and into the twentieth muffle kilns continued to be used by some manufacturers despite the introduction of open flame kilns of both up and downdraft design. The ability of pipemakers to adapt or experiment is shown by the surviving kiln at Broseley, built c. 1880 as an updraft open flame kiln with four fires and later converted to downdraft.