Steelmaking in a tiny open furnace

Donald B. Wagner
3 September 2010

Click on any image to see it enlarged.

At the annual conference of the Historical Metallurgy Society in West Dean, 2–3 September 2010, I was fascinated to see Lee Sauder, Steve Mankowski, and Shelton Browder convert mild steel (ca. 0.1% C) to tool steel (ca. 1% C) in a remarkably elegant way.

Lee tells me that this method was developed by Skip Williams, inspired by Ole Evenstad’s description in 1790 of a traditional Norwegian steelmaking method.

Janet Lang, Tim Sauder, and Steve Mankowski. In the background Jake Keen and two others.

The furnace was a shaft formed of clay with inside diameter 10 cm and height ca. 20 cm. The square chamber which can be seen at the side is merely an adapter to fit a large blast pipe to a small blast hole, ca. 6 mm i diameter.

	After drying, the clay was fired using wood both inside and outside the shaft. After firing, the shaft was filled with charcoal and ignited with full blast.
		12:00

The input material was eight rods of mild steel weighing in all 675 g.

A spark test shows that the carbon content of the bars is low.

	Charcoal was continually added to top up the furnace. One at a time the rest of the rods were added.
12:08		12:10


12:12	12:14	12:19	12:21	12:24	12:25

When all the rods had been charged, the charcoal was allowed to burn down.
	12:27	12:28

What remained was a layer of liquid slag over a solid button of steel.
	12:29	12:30


12:31	12:31	12:32
		Diameter ca. 10 cm, weight 392 g.

A spark test shows that the button’s carbon content is in the neighbourhood of 1%.
	12:35

To divide the button in half it was first cut halfway through with an angle grinder, then broken with a hammer.

The section, partly cut and partly fractured, shows that the steel contains virtually no slag.

Later Skip Williams sent me this picture of a different steel ingot, cross-section and micrographs. Carbon ca. 1.5%.

Lee Sauder is an artist-blacksmith and metal sculptor whose major passion for the last decade has been exploring the techniques of bloom smelting. He has run over 120 smelts, producing over a ton of bloom iron, most of which he forges into sculpture.

Stephen Mankowski is a journeyman blacksmith at Colonial Williamsburg, in Williamsburg Virginia. Has been doing traditional blacksmithing for almost 30 years and smelting iron traditionally for about 6 years.

Shelton Browder is a journeyman blacksmith in the Anderson Blacksmith Shop at Colonial Williamsburg in Williamsburg, Virginia. The focus of the work is to reproduce 18th century iron objects using the technology of the period. Shelton has been doing blacksmith work for thirty years with the last seventeen being at Colonial Williamsburg.

Skip Williams is an electrical engineer who has redirected his life toward working and building with simple technology.

When the furnace was hot enough, the first rod was charged.
	12:04