Charcoal kiln remains vary greatly. Smaller remains are usually those of farm kilns, which can be found at the base of hills with roads nearby, while larger remains oriented with a square stone base and occasional steel shells surrounding the base are commercial kilns, and usually placed near railroads. Commercial kiln locations can be found on historical maps from the nineteenth and early twentieth century.
Kilns vs. Pits
The use of the charcoal kiln had several advantages over the pit. Kilns were more expensive to manufacture, yet saved money in the long run—1.5 cents per bushel to be exact. Kilns were also able to produce more yield than pits, and the charcoal that was made was cleaner and fresher, as it was not in contact with the forest floor. Kilns were also conveniently able to be placed where they could be watched with more ease, as opposed to a pit, where colliers had to spend months in isolation. Kilns also reduced overall labor, as the covering was permanent, whereas the pit had to be covered manually each round. Transportation costs and damage to the charcoal also decreased with kiln use, which made it all the more popular. Charcoal kilns had the ability to produce 45 to 50 bushels of charcoal per wood cord.
The first charcoal kilns were made of brick or stone foundation and rectangular or round in shape; Typically 45 to 50 feet long and 12 to 15 feet high and wide. On average, onee kiln could fit 55 to 70 cords of wood, yielding 45 to 50 bushels of charcoal per cord of wood. Rounder kiln shapes were common in New England while rectangular shapes were more common in the south. Round New England kilns were typically 8 to 30 feet in diameter and 12 to 16 feet high with either vertical or battered walls. Additionally, round kilns had ankles, knee, and waist vents. By the late 1870’s conical kilns were replacing circular kilns. It is important to note that there are also kilns used to create limestone. The structure and function of limestone kilns are slightly different.
Limestone kilns were documented to have been found in Rhode Island and were 16 feet in diameter at the top, 13 feet in diameter at the center, and 10 feet in diameter at the bottom. These intermittent kilns that were small and operated by local farmers often produced irregular quality products.
- McVarish 2008, 265
- Straka 2014, 110
- Straka 2014, 110
- McVarish 2008, 262
- McVarish 2008, 259
- McVarish, Douglas C. 2008. American Industrial Archaeology: A Field Guide. Walnut Creek, Calif.: Left Coast Press, Inc.
- Straka, T. J. 2014. Historic Charcoal Production in the US and Forest Depletion: Development of Production Parameters. Advances in Historical Studies, 3, 104-114. http://dx.doi.org/10.4236/ahs.2014.32010