Making Charcoal at Greenwood Furnace State Park

( A version of this appeared in the July/August issue of Pennsylvania Magazine)

We circle the smoking cone, looking for “the eye of the fire-” a gaping hole with intense heat pouring out. Inside the dirt and duff covered pile of stacked logs, the charcoal “pit,” the temperature soars, turning the wood into charcoal. The hole or “mull” glows in the dark night and when we poke a stick in, there is an empty space, 12 inches deep. As the wood shrinks, it collapses in. Mulls tend to be on the windward side. Before oxygen can get in and burn up the wood inside at a rapid rate, we need to close it up and fast.

We hurriedly stuff in dried leaves and dirt, tamp it down with the back of a shovel and go back to our seats at the picnic table here at Greenwood Furnace State Park. We chat, snack, play harmonica, and learn about the early methods of making charcoal and iron in the furnaces of yesteryear. When you tend a charcoal pit, “there are long periods of inactivity, punctuated by moments of sheer panic,” our instructor and head collier, Paul Fagley says.  

Paul is Cultural Educator here at the state park, the site of an early 19th century iron furnace, and is responsible for putting on a fascinating array of educational programs, about 100 a year. Besides here at Greenwood, Paul travels to a handful of other state parks and historic furnaces around Pennsylvania to re-enact an actual charcoal burn. He  demonstrates how it was done years ago, allowing visitors to take part and interpreting the whole process and history. 

Charcoal tenders, or colliers, back in the 19th century, spent their summers in the forest during the “coaling season,” which spanned from April to October. The colliers pits were 30 feet wide at the base, conical in shape, and contained 35-50 cords of wood each! It took 3-5 days to build it and ten to fourteen days were needed to turn it into charcoal. In total, it took 25 days of work in each pit (compared to our 2!) and they could tend 8-10 pits at a time. These highly colliers were paid by their bundles of charcoal that they made. (2cents a bushel) The master collier could earn $1.50 a day in the late 19th century. Paul has recreated a pit that is fraction of the monstrous ones of old and we expect to turn this stacked and covered hardwood into charcoal in only a two-day weekend.

For this weeknd, Paul takes on the role of furnace owner, John A. Wright, donning period work shirt, wool vest and a rough and tumble slouch hat with a wide brim. He and his wife, Kim, set up a few easy-up tents, cook their meals on a gas camp stove and share shifts in monitoring the pit. Throughout the course of the 2-day burn, visitors stop in to watch the pit being created, monitor its progress and are present for the uncovering and raking out, revealing the finished charcoal.

The whole burn process began early this morning by dropping hot coals from the campfire into the top opening of the conical-shaped “pit” that Paul built. The center is packed with tinder and kindling, called “squaw wood.” These little dead branches that American Indian women used to gather can are found on evergreens and are very high in pitch.

Paul puts three shovelfuls of coals in and after 5-10 min., when the smoke increases, it “takes.” He replaces the “bridging” in a half moon shape- bark up, bark down, just one layer, re-seals it and pokes in air vents. It burns down in a cone shape.

As the hours go by, the oils burn off, as well as water, sugar, tar, and creosote – all the organic components of wood, leaving pure carbon, which is what charcoal is.

Because fire has free oxygen to it, the charcoal could burn down to complete ash and completely burn up. You can’t let that happen in a charcoal burn. It is a balancing act. If you are not careful, you could turn the whole pile into ash.

Even though our small, recreated pit pales in comparison to the monsters the colliers built years ago, ours still needs round the clock attending.

“Cave-in’s happens intermittedly. They breech all the time. Suddenly, the whole pit can reel in on you. It’s why you have to be here to tend it,” Paul instructs.

Local Ned Lynch takes a turn at watching the pit, circling it and looking for “eyes.” His ancestors were involved in the furnace industry as are many of the visitors who attend the charcoal burns. Descendents of furnace workers often return, relaying colorful stories and offering valuable artifacts and insight into charcoaling and furnacing. Paul uses much of this verbal material in his interpretations and presentations.

 This is Ned’s third burn but he feels he still has a ton to learn. Just take the color of the smoke- an indicator of what is occurring inside the pit. Now the smoke is pale and in full of steam since it is a half-day into the burn. If you pass your hand through, you can feel the moisture in the smoke. The water evaporates first, then, the sugars burn and the oils burn/volatilize in the later stages. The smoke is white and moist early on, then dry and yellowish later. (Campfire smoke is blue because of the carbon dioxide and vapors.) Cresote and other oils condense and work their way through the pit in the different stages of the burn. Learning to see and decipher color is like anything that you do over and over. It took a couple of burns for Paul to know what to look for.





Back in the 1900’s, the colliers’ job was a very important one for charcoal was a key heating ingredient in the smelting of iron ore. George Washington was depending on the cannons and iron cannon balls made here at Greenwood Furnace to help win the Revolutionary War. 


Furnaces consumed 800-1,000 bushels of charcoal a day, (about an acre of forest) and stripped 300 acres of forest per year. Five thousand cords of wood were needed to feed the hungry furnace in a single year’s time! Stacked end to end, that pile would be four feet square by seven and a half miles long. They tried to checkerboard the land so they had to go out varying distances but often traveled up to 10-12 miles for wood.

The forest around the state park is solid timber now, in 70 years of operation, the forest was charcoaled approximately three times. 


Although most of the land looked denuded back then, the ironmaster and furnace owner were some of the first conservationists and forest stewards. For unlike the timber industry, whom slashed and moved on, leaving behind devastation, the furnace men had to manage their trees or the furnace could not be fed. When the iron smelting industry was taken over by the coal industry, many of these mountain lands were acquired by the state and became part of the new Division of Forestry as public lands.





Paul sits at the picnic table with oil lamps and chunks of iron ore, limestone, etc. explaining the furnace process to campers who stop by to check on the pit.

We lick the iron oxide rock and it tastes rusty, like iron, like blood (which has iron in it). Paul explains what pig iron is and equates it to baker’s chocolate in the steel-making recipe.


People come here and say, “Tell me about furnaces. Most people who go to historic sites have seen the history channel and have some reference points. History is dull and boring so I tell people about the motivations and passions of those who came before, and suddenly history becomes exciting.”


Paul and the park have developed a genealogical database (of over 6,000) for visitors whose ancestors were involved in charcoal making and the furnace. The project began when they commented on the displays, sharing that they knew a worker from the past or saw their grandparent’s photo in the display case and wanted information. Their stories became incorporated into Paul’s interpretive programs.



Tonight I’m sleeping in a tent, but the smoke-covered woodsmen of old, slept in very crude huts made of wood, earth and logs that they constructed every spring. They were filthy men, covered in black oils from the burning wood and charcoal dust that seeped into their pores and permanently tatooed them. It wasn’t desirable to appear clean, for the unwritten law of the collier said that to be clean was a sign of inexperience. “A clean collier was a green collier.”


They rarely bathed from April through October and the soot made its way into their huts and food. As a rule, the men saw nothing of their families from Monday morning until Saturday night, at which point they were probably told to promptly get in the washtub and scrub!


All sorts of snakes took a liking to their huts and would “drop in” from the ceiling or curl up in the collier’s beds. Since snakes eat toads, the men kept a few in their huts as snake-alarms. When one was missing, they knew to go on a snake-hunt and evict the squatter. After the charcoal-making season ended, the colliers burned their infested huts down!



When Ned and I call it a day, we know Paul’s job is just about to begin. He’ll have to check on the pit every 1/2 hour- take a walk around it, probe it with a 6-foot long pole. Before we leave, Paul reports that the center’s temperature is 1500-1600 degrees and the surface 7-800 degrees. Years ago, a collier never got full sleep from late April/early May to mid October.





A pit burns as the fire moves towards the source of oxygen- the air vents at the base. When the fire line reaches the bottom, it is called “coming to foot.” It means the wood has completely charcoaled, but Paul is having his doubts this morning.


He tests the pit by poking it with a potato fork. He crunches through the charcoal and after only one inch, he can “feel” solid wood. Not good. Last night, the park experienced hurricane rains. The rain blew a 2-foot drain hole in it and rainwater got in. It pooled inside and created steam. If the pit was larger and there was more wood to burn, the fire would have burned hotter and faster. It takes a lot for rain to put the fire out or prevent it from burning hot for the leaves act as shingles. Last night was unusual.


To “damp off the pit,” dirt is piled on top to seal it off, the fire is smothered and normally allowed to sit for a couple of hours before opening it up and raking it out. But when Paul opens up our pit, there is still fire in there and the pit is steaming. Because of the heavy rain, it got pretty wet. At this point, there should be very little smoke. The pit is soaked.


When the charcoal is raked out, it sounds like tinkling, broken glass. A lot of the pieces have iridescent colors in them like a rainbow. As soon as it absorbs moisture from the atmosphere, the color disappears. As Paul introduces oxygen, the fire takes off again.


There are a lot of “brands” – half charcoaled pieces of wood. Normally, they are only found near the edge and a collier aimed for only 1% brands. They were raked to the side and used in the next pit to finish off the process. It was called “foxing the brands.” But we have tons of brands because the charcoaling process was halted.


Paul suspected that the pit was no longer charcoaling in the night. It never mulled once which is very unusual. The rain had cooled the pit off. It was just enough moisture to overcome the heat. We didn’t quite have the volume to surface area to overcome it. The big piles in real life would not have been affected even by a huge amount of rain. It’s been a lesson. That’s why we are here.



Years ago, once the charcoal was finished, it was loaded onto huge wagons that could carry 300 bushels in a load. Iron furnaces ran 24 hours a day, seven days a week, for many months on end and needed tremendous amounts of charcoal. At one time, Pennsylvania was thought to have over 500 furnaces and forges throughout the state. The Commonwealth led the country in iron production because we had every ingredient that was necessary: iron ore, limestone, and waterpower.


Today, the park uses the charcoal Paul creates in the blacksmith shop during demonstrations, which is what they used to before coal was discovered. It is free of sulfurs, no impurities.


We are looking for white, which means the wood is still burning. Ned rakes, Paul squints, looking hard. “Let’s find these smokers.”  There can be a little spark down inside and we’ll need to put it out, just for safety, for it can burst into flames hours later.”


Paul tells me I’ll have to return and attend another, “more successful burn” sometime, but I feel swelled with knowledge and satisfied. I know a lot more than I did before arriving at the state park 24 hours ago, plus I had a lot of fun. Feels like success to me. I toss a few chunks of dead, cold charcoal onto the floor of the back seat of my car, to perfume the air and remind me of the woods, the trees, days gone by, and a lost art that is still alive here at Greenwood Furnace State Park.


Greenwood Furnace State Park

(814) 667-1805




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