The Cold Blast Era of Danville’s Dawning Iron Age.
Danville is well known for its iron heritage, but few people know that this heritage was fueled first by charcoal. In the first iron forges and also the first iron blast furnaces, where iron ore is smelted into iron, charcoal was the fuel. The first 2 local furnaces were the Danville No. 1 and the Liberty (in Mooresburg). They were built in 1838 and were put in to blast by 1839 using charcoal. Anthracite coal was not adopted until a few years later. Prior to the introduction of the hot blast furnace, iron could not be smelted with anthracite coal or coke, so charcoal was the only fuel available.(Fagley) Older charcoal furnaces later were known as "cold blast furnaces," as the air was not heated. By the 1840s, hot blast anthracite furnaces were being built and many charcoal furnaces adopted the technology. Hot blast furnaces captured the heat escaping out of the top of a furnace and used it to heat fresh air being pumped into the furnace. All furnaces that used coal or coke were hot blast, and there are a few surviving examples of charcoal furnaces using the "hot blast method," for example the Joanna Furnace in Berks County PA. (Pawling)
Charcoal is baked hardwood. The men and women who made charcoal were called “colliers.” Colliers spent the winter months cutting hardwood species of trees on Montour Ridge and Sidler Hill and stacking the split, 3-4 foot billets in piles to season or dry. The burning or coaling season was from May – October due to dangerous winter winds and other winter weather conditions that made coaling unfavorable then. The most ideal trees were oak, hickory, chestnut, and other hardwoods. Pine and softer woods were used occasionally but were not preferred.
It takes about 1 acre of forest to make enough charcoal for 3 tons of
pig iron per day (Pawling). The Liberty and Danville No. 1 furnaces
were each producing 20-30 tons of iron per week, that’s 4 tons a day each
(furnaces ran 7 days a week when in blast). That’s 1.3 acres per
day each. This does not include charcoal made for blacksmithing
and forging iron. The demand for charcoal was significant and eventually
caused greater demand for a cheaper substitute, anthracite coal.
(HOPEWELL Village National Historic Site, Pennsylvania)
The coaling process
To make charcoal, split billets of wood 4-5 feet long were stacked in a large mound on a flat surface 30-40 feet in diameter and as high as 20 feet. Each mound or “hearth” held 25-50 cords of wood. As the mound was built, a triangular chimney was created in the middle of the mound. The entire pile would then be covered with a layer of loose top soil about 1 foot thick. A small opening would be left for the chimney. “Firing the pit” was the phrase used for igniting the mound. This was often done in the evening to allow for one last good nights sleep for the collier. For the next few days and nights, the collier would get little sleep as the smoldering mound would need constant watch. If the fire grew to hot, it would consume the entire pit and burn all the fuel. If it burned too slowly the quality would be insufficient.
(Colliers hut with stacked chordwood in background. HOPEWELL Village National Historic Site, Pennsylvania)
The colliers lived in small huts built in the center of several mound locations. An experienced collier would keep watch over several burning pits at one time. If the glow of the fire became visible the collier would spring to action and apply more dirt to the area. This was called “jumping the pit.”
Once the mound was sufficiently burned, the collier would “rake the pit.” The top layer of dirt was removed so the charcoal could be raked into bushel baskets and loaded into horse or mule drawn wagons. 100 parts of wood yield about 60 parts by volume, or 25 parts by weight of charcoal.
(Raking the pit, HOPEWELL Village National Historic Site, Pennsylvania)
It is unclear when the last local charcoal was made because charcoal
making continued long after iron furnaces switched to anthracite coal.
Charcoal was still used by some blacksmiths. Also charcoal is a key
ingridient in black powder, the explosive used in Danville iron ore mines
and limestone quarries. The ore mines all closed by 1889 locally.
The limestone quarries probably switched over to dynamite by the turn of
the century. This is probably when local charcoal making ceased completely.
2007 Charcoal Marking During Iron Heritage Festival
A project is underway to create charcoal in Danville for what is probably the first time in a century. Bradd Mertz, Kristin Joivell, and Van Wagner are leading the effort to turn chords of hardwood into charcoal to then be used for smelting local iron ore into iron. The 2007 charcoal pit will be as historically accurate as possible. The public will have a first hand view of the coaling experience. The sights, smells, and sounds of charcoal will return to Danville in early July 2007.
The charcoal pit will be prepared in early July at the F.Q. Hartman
field in Danville. The public is welcome to visit during preparation
of the pit as well as construction of the mound. The "firing of the
pit" will take place approximately 1 week before the start of the Iron
Heritage Festival. More info TBA.
From the Colliers' Lexicon
Brands: Partly charred billets which remain after the pit has been coaled.
Butt: The final remains of a burned-off pit.
Coaling out: Act of digging and raking charcoal from the pit.
Foxing the brands: Recoaling the partly burned billets after the charcoal has been hauled away.
Dressing the pit: Refilling a mull, where the fire had burned through, with new wood, leaves, and dust so that the exterior of the pit was restored to its original shape.
Head: The uppermost layer of lap-wood forming the rounded top of the pit.
Head dust: Old charcoal dust placed on top of the pit to form a smudge blanket.
Lapping off: Placing lap-wood on the outer surface to make the pit as tight as possible.
Piece: The pit after some of the coal has been removed.
Pit will blow: Gases generated by the charring wood often cause the top of the pit to blow off.
Shoulder: That part of the pit where the second tier of billets meets the top layer of lap-wood.
Waist: The portion of the pit where the first tier of billets meets
the second tier.
American Charcoal Making, Hopewell Village National Park publication (no date)
Richard Pawling History Alive!, Sinking Spring PA
Bradd Mertz, Blacksmith / historian Danville PA
Sis Hause Historian Danville PA
Paul Fagley, Cultural Educator Greenwood
Furnace State Park (PA)