Iron

Note: This post is a sketch of a topic I hope to cover in more detail in a feature-length story. Stay tuned…

One of my oldest friends is the blacksmith Shel Browder. Shel retired a couple years ago from a long career at Colonial Williamsburg, and now does freelance work for a number of individual and institutional clients. Now blacksmithing is an even smaller profession than, say, archaeology…they ALL know each other, so it’s not too surprising that Shel connected with Lee Sauder. Lee is a well known smith and sculptor from southwestern Virginia, and he’s also one of the country’s real experts in the pre-industrial manufacture of iron. At last weekend’s project at the Virginia Museum of Frontier Culture in Staunton , Lee, Shel, Chris Furr the Museum's staff blacksmith, and a few Museum staff and volunteers helped resurrect the craft of bloomery iron.

Blast furnaces, such as those that operated at Pennsylvania’s Cornwall or Carlisle works or many other places in 18th century America, could produce iron continuously (i.e. remain in blast) for months, the liquefied iron pouring from taps at the base of the furnace into prepared sand molds, and hardening into solid bars called “pigs” (i.e. pig iron). Blast furnaces didn’t appear in Europe or anywhere else much before the 16th century. Prior to that, all the way back to the dawn of the Iron Age in Europe, Africa and Asia, iron was made in bloomery furnaces. These small furnaces persisted for centuries after blast technology appeared, and were likely employed in the earliest American colonies during the 17th century, and in out-of-the-way places worldwide.

Typically, these are small chimneys fashioned from clay, and equipped with a bellows. Equal weights of charcoal and roasted iron ore are fed into the top in incremental and alternating layers, and silica impurities (AKA slag) and molten but not-quite-liquid iron (a bloom) appear at the bottom. The process appears deceptively simple, but in fact is fraught with complexities not easily solved since the real experts have been gone for centuries. The scale also seems very limited, until one considers that the armories and all the tools of three continents were amply supplied by these small pre-industrial workhorses for centuries.

Lee has thrown himself at this process. He has read everything there is to read, talked with archaeologists, metallurgists, and other smiths, and even traveled to Africa to work with smiths who are trying to reconstruct their ancestor’s methods from traditions that may not have died out there until the 1950’s. He has failed spectacularly many times, but he has learned from all of them. He and Shel were kind enough to invite me down to observe last weekend’s demonstration (Lee’s 167th ) and I took some photos and video that will hopefully explain the basics of this nearly vanished industry.

Friday the 18th: Building and Hardening the Furnace

The furnace is constructed of clay tempered with sand and coiled around a wooden form. Each course of clay is bound with twine to help delay slumping and keep it generally in place.

Building the Furnace

When it’s complete, a perforation for the tuyere (a copper tube that will carry air into the furnace) and the mouth of the furnace are scribed in the wet clay, as is a small perforation near the top. Lee learned to put in this perforation from his African friends who explained that it was put there “so God can see”. When Lee asked if it was so God could see out or in, they looked at him like he was a stupid and crazy American (which, he opined, might have been true). A small fire is then built around the outside of the furnace, drying the clay a bit, and helping to keep it from slumping. The mouth of the furnace is then cut open, and the fire is introduced into the interior where it consumes the wooden form. After several hours of burning, the clay is hard enough to begin its life as a furnace.

Completed Furnace

Burning and Hardening the Exterior

Opening the Base and Burning the Interior

Burning and Hardening Friday Night

Mouth of the Furnace

Saturday the 19th : The Bloom

In the morning, preparations are made to actually smelt the iron. The bellows, in our case an electric blower that connects to a copper tuyere, is set in its receptacle at the proper angle. A hand operated bellows can be used, but once the 5 hour long smelt begins, it can never stop pumping or the tuyere will melt. A team of many bellows operators, or a water powered wheel, would be necessary. A preheating fire is kindled, and the mouth of the furnace is sealed with a clay patch. The patch is built in sections that can be removed in sections, first at the very bottom to drain off the slag, and later the rest will be removed to extract the ball of hot iron or bloom.

Setting the Tuyere

After preheating for an hour or so, the process begins. Alternating additions of wood charcoal and roasted iron ore are added at the top of the furnace. The ore is from a local source near Lee’s home, and it’s simply roasted in a wood fire to drive off excess water and make it easier to break into smaller fragments to facilitate melting. Lee also makes his own charcoal in a home-made contraption that, apparently, used to be a dumpster! Equal weights of ore and charcoal (I forget how much) are used in the smelt.

Charcoal

Roasted Iron Ore

The smelt proceeds for five hours or so. The internal temperature of the furnace reaches approximately 2800 degrees Fahrenheit! It sounds like a rocket ship. Longitudinal cracks appear releasing flames and hot gasses, but it holds together, and in fact, can be reused several times.

At about four hours, Lee breaks out the base of the mouth and hot slag pours out and puddles in front of the furnace. The slag is mostly silica with some iron and other inclusions. It flows around and puddles beneath the bloom now formed in the base of the furnace. Apparently there was so much bloomery slag laying around parts of Italy from Roman times, that Mussolini mined it and used it to produce iron and steel in modern blast furnaces during the Second World War. 

Preheating

Charging the Furnace

In Full Blast

Tapping the Slag

At about 5 hours all the ore and charcoal have been added, and the bloom is ready to extract.

Once out of the furnace, the roughly 20 lb bloom is carried to a nearby wet section of log for hammering and consolidation. The log is used because the red hot iron will burn its way into the wood creating a cradle for itself, making it much safer to hammer than it would be on a flat anvil. The hammering consolidates and aligns the bloom, and also eliminates some impurities.

  It’s then cut with an axe and hammers, and the smaller pieces can be reheated in a forge, and hammered into bars on an anvil.

These bars were what a bloomsmith produced and sold to blacksmiths, armorers, and other craftsmen, who then forged them into a variety of good and useful things.




Many thanks to Lee, Shel, and the good folks at the Virginia Frontier Culture Museum for allowing me the privilege of seeing one of the world’s oldest crafts preserved for the future!