Limeburner
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Le Chaufournier | The Limeburner
A lime burner and kiln (sketch in l’Encyclopédie ou dictionnaire raisonné des sciences, des arts et des métiers (1751), L'Histoire de la Chaux, http://chauxboehm.fr).
The chaufournier, or limeburner, was a lime kiln operator. In French, the lime kiln is called a four à chaux.
In the construction of buildings with very thick walls that were meant to be resistant to gunfire or cannonballs, the mason had to bind the stones to each other with a mortar made of sand and cement.
This mortar made of limestones was baked in a kiln at more than 800°C by the limeburner, day and night, for seven or eight days. The secret to success was producing a progressive fire which would start to make the stones crack. Once that happened, the limeburner would accelerate the fire and maintain it at its maximum to reduce the stones to powder. He knew the baking was done when the stones turned the colour of sulfur. At this stage, the limeburner took the resulting hard cake of quicklime (calcium oxide) and added it to water. It would immediately react producing a shower of caustic specks of slaked lime (calcium hydroxide). The crumbly grains were then crushed into lime powder and that was then added to sand to make mortar.
The profession was deemed extremely dangerous because of the toxic vapours like carbon monoxide released by the oven. This could easily make a worker drowsy or even paralyze them and then suffocate them. The limeburner had to wear thick leather gloves to protect his hands. It was a seasonal job, with kilns only operating between the spring and fall, as long as it wasn’t snowing.
This type of oven existed as early as 1686 in Montreal and 1689 in Pointe-de-Lévy.
Known persons that had this occupation: Mathurin Arnault, Jacques Beauvais, Antoine de Lestre
Lime kiln and limeburners ("Four à chaux", sketch by unknown artist, Les Amis du Clocher et du Patrimoine de Caux, http://lesamisduclocherdecaux.wifeo.com).
"Making lime from oyster shells in a kiln" (1625 sketch by Sidney E. King, Fine Dictionary, www.finedictionary.com).
Watch this video to see how lime was made throughout history.
Sources:
Claude Lemay, "Fonctions et métiers délaissés", l'Ancêtre, number 281, volume 34, winter 2008, and number 280, volume 34, winter 2007; electronic edition, Société généalogique de Québec (www.sgq.qc.ca/images/_SGQ/R_LAncetre_plus_libre/ENT-FONCTIONS-METIERS-DELAISSES.pdf).
Jeanne Pomerleau, Arts et métiers de nos ancêtres : 1650-1950 (Montréal, Québec: Guérin, 1994), 143-147.