Hot Enough to Smelt
On a day warm enough to discourage backyard grilling of hot dogs, students and technicians from the Applied Research Center were standing around a yard in Colonial Williamsburg helping to heat a clay oven up to 600 degrees. Celsius.
"The idea at Colonial Williamsburg was to try to rediscover the process of converting local ores to a workable material wrought iron," said Steven Mankowski, a journeyman blacksmith in the CW smithy. "One of the processes that we are experimenting with is the direct method of making iron with what is called a bloomery. We have been curious about this technology for years, and with the 400th anniversary of Jamestown coming up, it seemed like a good time to start."
A bloomery is essentially a clay oven and is an ancient method for smelting iron, long predating the Jamestown colony. Shelton Browder, a journeyman blacksmith in the CW smithy, explained that wrought iron is distinct from cast iron, which requires a blast furnace. The manufacture of bloomery iron basically consists of heating up a mixture of charcoal and iron ore. It's certainly "low tech," but it's also "lost tech." The knowledge, lore, skills and knack that are necessary for getting a consistently good iron bloom have gone the way of flint knapper and the linotype repairman. The blacksmiths set up a bloomery in the side yard of the smithy to produce their own iron from ore, starting with a mix of locally mined ore and commercially purchased ore.
As a shortcut for recovering lost knowledge, the smiths got in touch with Amy Wilkerson, manager of the Surface Characterization Lab at the Applied Research Center in Newport News, usually known as the ARC. Wilkerson presides over an impressive array of instrumentation and for years has incorporated a steady stream of William and Mary students--along with the occasional high-performing high schooler--into the mix as paid interns. Wilkerson and her colleagues agreed to put the smiths' attempts at making 17th Century iron to a series of 21st Century tests.
"There are other people in the country doing this," Brower said. "But we have the best lab in the country helping us out."
William and Mary students (from left) Dina Abdel-Fatah and senior Christopher Hendricks look over a piece of bloomery iron with journeyman blacksmith Shelton Browder.
Go On, Try the Bellows!
The collaboration is highlighted by an exchange of visits between the smithy and the ARC, shops representing the extremes of ferrous metallurgical technique. The apparatus for making bloomery iron is pretty simple: a large bellows connected to a clay oven by an airpipe known technically as a tuyere. Charcoal and iron ore go into the oven, to be baked at a high temperature made possible by a constant draft of air. The bellows, of course, is worked by hand. It looks like fun when you first see it done, but the students found that the bloom needs oxygen long past the time at which working the bellows is entertaining.It's been an ongoing win-win relationship, characterized by learning on both sides. Christopher Hendricks, a William and Mary senior from Baltimore, was put in charge of researching the literature.
"I looked up other examples of old wrought iron--tools, and that kind of stuff--trying to see if our pictures that we were getting on our microscope were similar to examples that other people have used for their work," he said. "I noticed that they did look really similar. One of the articles gave hardness measurements, so we figured that would just be another area to test the local wrought iron that they produced and compare it against some known samples cited in these articles."
At one visit to the smithy, lab tech Olga Trofimova discussed the group's findings after putting the first batch of iron through a battery of tests. The ARC lab team compared the newly smelted iron with samples of old iron provided by the smithy, using techniques such as energy-dispersive X-ray spectroscopy. Trofimova reported early results that showed the bloom had higher carbon content than expected, plus a mystery--presence of copper, despite a complete absence of copper in her analysis of ore samples used in the bloom.
"We know where that's coming from," Browder said, exchanging knowing looks with Mankowski. He explained that the tuyere supplying the oxygen to the bloomery is a heavy copper pipe--the only possible source of the trace metal in the samples. Theoretically at least, the copper should hold up to the intense heat of smelting as long as the supply of air is uninterrupted.
William and Mary student Dina Abdel-Fatah in the lab.
Carbon Content Is Crucial
The smiths were especially interested in the carbon content of their iron. Browder explained that low-carbon iron is more plastic, therefore easier to work on the anvil, but that some uses might call for a higher carbon content. Dina Abdel-Fattah of Yorktown, now a first-year student at William and Mary, assisted Trofimova in analysis of carbon content while still a student at Tabb High School."I basically do a lot of the calculations, like I average the stuff out and see how much carbon, and other elements are present in the samples after we do the EDS scans," she said. "We found higher content than expected of carbon in this batch, and with time we will figure out where it is coming from."
The analysis of new bloomery iron is in the very early stages. There are a number of analytical tools in the Surface Characterization Lab that have yet to come into play. As the smiths learn to refine their understanding of the ancient technology, Christopher and Dina and the other students in the ARC's Surface Characterization Lab have the opportunity to participate in real-world research.
"Instead of getting a sample off the shelf and learning to do analysis, the students can see exactly how their work will be of benefit," Wilkerson explained. "And they don't spend their time wondering why they're doing what they're doing. I really like to see the excitement that they show when they discover something in the lab. It's real. You can see it in their faces--'Hey! I did this!' They gain self-confidence, and it's the kind of self-confidence that they wouldn't get from working in a restaurant or some other job."
By Joe McClain for Ideation magazine
©2009 · Arts & Sciences at The College of William and Mary