Early Modern Fire

Architectural terracotta in modern France was produced through an operating chain where an imposing kiln held a central place. This was no high technology, but required a specific know-how as to the "manner of conducting fire." The oven could be a masonry oven fuelled with wood, or an "open" coal kiln built with the very bricks that were to be fired; both these structures made use of relatively stable techniques from the Middle Ages to the beginning of the twentieth century. The appearance of smoke and the colour of the walls remained the main indicators to handle the firing process. The kilns construction underwent some slow changes aimed at improving the circulation of fire in the firing chamber, but the difficulty of controlling fire, coupled with the economic catastrophe represented by a failed firing, often pushed tile makers to invoke supernatural powers to protect their kilns. Beyond these technical aspects, due to the growing wood shortage that affected modern Europe, tile makers using wood-fired ovens (50 to 100 cubic meters per firing) were subject to increasing pressure as to fuel supplies. Preservation measures were taken by various authorities as of the sixteenth century, but many establishments still found themselves in great difficulty until the mid-eighteenth century. The first tests of coal firing (or more rarely with peat or other types of fuel) were attempted at this time, with mixed results due to low availability of the chosen fuel, an incomplete technical mastery, but also the resistance to culture change. Another possibility was to radically innovate the oven construction, in order to reduce its wood consumption. If this dynamic gave birth in the mid-nineteenth century to new technical solutions, some still in use today, this movement of innovation was ongoing since at least the end of the eighteenth century: some inventors thus proposed the first models of juxtaposed or superimposed kilns, recovering heat from a fire to preheat the nearby oven. These first tests, remaining for the most part without future, did not question the prevalence of the craftsmen's know-how: the superimposed kiln of the baron de La Tour d'Aigues, in 1787, was thus tested by ‘people of the countryside', who still had to rely on their senses to guide the firing, not through sight but the ‘considerable noise [of] the air column'.