Charcoal production

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Background

In nineteenth century Pennsylvania, charcoal was produced primarily to fuel iron production. Charcoal is the result of the destructive distillation of wood to yield a fuel that is primarily carbon[1]. Charcoal retains the texture of wood, is black in color, and is fragile under pressure[2]. Charcoal was used in iron production rather than pure wood because charcoal burns much hotter and more consistently[3]. In the 19th century, when iron production was at its peak, the demand for charcoal as fuel for furnaces directly impacted forests. As a result, the charcoal industry was one of the first to think about sustainability and forestry.

Types of Wood

While most types of wood can become charcoal, hard woods generally produced the best quality charcoal. Trees like oak, hickory, chestnut, and elm were greatly preferred to softer woods, such as gum and poplar[4]. However, heavier hardwood required a longer burning period[5], so sometimes a mixture of hardwood and softwood proved to be a combination that yielded the greatest quantity of charcoal[6] without compromising the integrity of the material. The condition of wood was also important to the quality of the charcoal output, as knots in the wood, decay, and moisture all negatively impacted carbonization[7]. The burning process reduced the weight of the wood by roughly a quarter and the volume of the wood by half[8].

The wood was cut by woodcutters primarily during the winter months[9], as the trees would have less moisture inside[10]. Two type of wood were cut: lap-wood and billets[11]. Both were cut in a particular fashion that allowed them to slant inward when piled together[12].

Charcoal Production Process

Making the Hearth

Charcoal hearths required a large, flat, solid, and dry area[13] that was typically thirty to forty feet in diameter[14]. They were often constructed on hillsides to facilitate dirt movement and were usually round. A triangular chimney was constructed from stacked wood in the center of the hearth. In the chimney, a large stick called the Fagan pole was inserted[15]. The Fagan pole was used to mark the center of the pit (the term "pit" is not an accurate descriptor of the appearance of the hearth, as the structure was entirely above ground) and would be also be removed to provide draught just prior to the process of burning the wood[16].

Piling the Wood

After the chimney and the pole were constructed, the collier leaned thick pieces of hardwood inward against the chimney and filled the gaps with lap-wood[17]. After the first layer (the "foot") was created, the second layer (the "waist") was built up four feet in height[18]. Then, a third layer (the "head") was added to the chimney, completing the structure[19]. A pit may have held anywhere from twenty-five to fifty cords of wood at a time[20].

Covering the Wood

Piles were first covered with a layer of leaves or straw that is about an inch thick[21]. Then, a four inch layer of charcoal dust and dirt was added[22]. The leaves acted as a barrier between the wood and the dirt, helping to ensure even charring of the wood by restricting air flow[23].

The Burning Process

Charcoal hearths were likely lit at the top and burned downwards[24]. To ignite the wood, kindling was placed within the the chimney and the fagan pole was removed[25]. Then, hot coals were dropped into the chimney and the opening was covered with a flat wood pieces called the "bridging." The bridging was then covered with leaves and straw[26] before the burning began.

The process typically took between ten to fourteen days; however, if conditions were unfavorable, the burning period could take three weeks[27]. The type of wood, its quality, the way the wood was piled, and the number of cords also factored into the length of the burning process[28]. During the process, the pit was carefully observed and tended to by colliers to ensure that the wood was burning evenly[29]. White smoke was one of indicators of a proper burning[30]. At five hundred degrees Fahrenheit the wood began to break down; the maximum temperature reached during the process was about seven hundred and fifty degrees Fahrenheit[31].

The process was ended before all the charcoal had finished burning because this helped colliers maximize production[32].

Removing the Charcoal

To remove the finished charcoal, colliers used a large rake with long tines[33]. The tines ensured that the pieces of charcoal were dragged through the dirt on their way out of the hearth. This made sure that no fires would flare up and destroy the charcoal[34].

Sustainability

The need for charcoal in the iron industry created a significant demand for wood and a great deal of trees were chopped down for its production. The average output of furnaces between 1750 and 1800 was one hundred to four hundred tons of pig iron per year. This required two hundred to four hundred bushels of charcoal and fifty acres of trees to produce that amount[35]. Even though the increased efficiency of furnaces decreased the necessary amount of charcoal, increased production required one hundred and fifty acres of wood by 1850 and one thousand four hundred acres by 1900[36].

Since forests regenerated at different rates, this impacted sustainability. In the Western United States, woodlands took decades to regrow to maturity; so, forest sections usually were cut on a twenty-year cycle[37]. Old-growth forests would typically have higher yields[38]. Eastern furnaces were some of the first to manage forests to ensure a sustainable yield[39]. Several early proponents of sustainable forestry were involved in the making of charcoal, like Bernhard E. Fernow, the manager of the Lehigh Furnace from 1879 to 1883. He advocated for coppicing of wood and protection from fire and cattle grazing to speed up regrowth of forest used for charcoal[40].

Charcoal versus Coal

The transition to coal as the primary fuel for furnaces began around 1840, but in 1859 around three-quarters of furnaces in America (particularly in Ohio, Pennsylvania, and New York) still primarily used charcoal[41]. Charcoal remained a source of fuel in some places until 1945[42]. Coal was chosen as a replacement for charcoal in part because it was less expensive to transport[43].

Charcoal, compared to coal, tended to produce a higher quality of iron with fewer impurities, partially because of its density[44]. The use of charcoal also created less smoke using the production process[45]. Iron made from charcoal had a "fine grain" and maintained a better cutting edge[46] in comparison to coal. However, as coal became the primary source of fuel, production moved out of the forests and into cities, which allowed the forests to begin to recover from the impacts of charcoal production.

Collier Life

Historically, the collier profession was not one for the faint of heart, as great skill was required in order to successfully maintain multiple charcoal hearths at one time for months on end[47]. Living alone, or occasionally with a son or apprentice, colliers could not afford to lose concentration for even one moment, as the slightest wayward breeze or hole in the charcoal hearth could cause irreparable damage to the charcoal[48]. The quality of charcoal was important to colliers' livelihood as high quality charcoal rated higher prices[49]. The collier profession required almost constant twenty-four-hour surveillance of the hearths [1]. A dangerous role a collier must perform was called"jumping the pit." This crucial job required a collier to climb onto the hearth and place more wood into any "soft spots" in the pile[50]. If anything went awry, the collier risked falling into the smoldering charcoal fire[51]. While making charcoal, colliers lived in Collier huts. During the winter months, colliers became wood-cutters in order to get a full-years wage, as the ideal season for production of charcoal was during the warmer months of the year[52].

Notes

  1. ↑ Straka 2014, 106
  2. ↑ Svedelius 1875, 20
  3. ↑ Straka 2014, 106
  4. ↑ Straka and Ramer 2010, 59
  5. ↑ Straka and Ramer 2010, 59
  6. ↑ Straka 2014, 106
  7. ↑ Straka 2014, 106
  8. ↑ Straka and Ramer 2010, 59
  9. ↑ Straka and Ramer 2010, 59
  10. ↑ Svedelius 1875, 6
  11. ↑ Straka and Ramer 2010, 59
  12. ↑ Straka and Ramer 2010, 59
  13. ↑ Straka 2014, 106
  14. ↑ Straka and Ramer 2010, 61
  15. ↑ Straka and Ramer 2010, 61
  16. ↑ Straka and Ramer 2010, 61
  17. ↑ Straka and Ramer 2010, 61
  18. ↑ Straka and Ramer 2010, 61
  19. ↑ Straka and Ramer 2010, 61
  20. ↑ Straka and Ramer 2010, 61
  21. ↑ Straka and Ramer 2010, 61
  22. ↑ Straka and Ramer 2010, 61
  23. ↑ Straka and Ramer 2010, 61
  24. ↑ Straka, 2014, 107
  25. ↑ Straka and Ramer 2010, 61
  26. ↑ Wagner, 2008
  27. ↑ Straka and Ramer 2010, 61
  28. ↑ Straka and Ramer 2010, 61
  29. ↑ Straka and Ramer 2010, 61
  30. ↑ Straka and Ramer 2010, 59
  31. ↑ Straka and Ramer 2010, 59
  32. ↑ Wagner, 2008
  33. ↑ Straka and Ramer 2010, 61
  34. ↑ Wagner, 2008
  35. ↑ Straka 2014, 105
  36. ↑ Straka 2014, 106
  37. ↑ Straka 2014, 111
  38. ↑ Straka 2014, 105
  39. ↑ Straka 2014, 111
  40. ↑ Straka and Ramer 2010, 60
  41. ↑ Straka and Ramer 2010, 59
  42. ↑ Straka and Ramer 2010, 61
  43. ↑ Straka and Ramer 2010, 59
  44. ↑ Straka and Ramer, 2010, 59
  45. ↑ Straka and Ramer, 2010, 59
  46. ↑ Straka and Ramer 2010, 59
  47. ↑ Straka and Ramer 2010, 60
  48. ↑ Wager, 2008
  49. ↑ Straka 2014, 106
  50. ↑ Straka and Ramer 2010, 60
  51. ↑ Straka and Ramer 2010, 60
  52. ↑ Kemper 1941, 10

References

  • Agriculture and Rural economy – Charcoal → . 2010. The Encyclopedia of Diderot & d'Alembert Collaborative Translation Project. Ann Arbor: Michigan Publishing, University of Michigan Library. http://hdl.handle.net/2027/spo.did2222.0001.346 (accessed [fill in today's date in the form April 18, 2009 and remove square brackets]). Originally published as "Agriculture et économie rustique – Charbon de bois," Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers, vol. 1 (plates) (Paris, 1762).
  • Jones, Claude A. 1976. Making Charcoal at Jacobsburg. In Slate Belt Bicentennial Heritage, edited by Marjorie May, Maryann Repsher, Robert R. Saltern, Gordon E. Wilson, and Albert M. Toth, 32–33. Heritage Committee of the Slate Belt Bicentennial Commission.
  • Straka, Thomas J. 2014. Historic Charcoal Production in the US and Forest Depletion: Development of Production Parameters. Advances in Historical Studies: 104-114. http://dx.doi.org/10.4236/ahs.2014.32010
  • Svedelius, G., Joseph Leonard W. Nicodemus, and Björn R. Anderson. 1875. Hand-book for Charcoal Burners. New York: Wiley.
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