Metalworking Symposium 2004
Farmer's Museum - Cooperstown, NY (10/9 - 10/11)
Modern Smelter
11th Century Norse
Coupola Smelter		 6th Century Japanese
Tartara Smelter
Michael McCarthy (full time blacksmith at the Farmer's Museum) assembles the tuyeres.
11th Century Norse Coupola smelter. The shaft stood approx 2.5' over all; 1/2 above ground and 1/2 below. This setup offered more support to the base since previous trials had a tendancy to sag once up to operating temperatures. Smelter ID is approx 10", OD approx 12"
The tartara stood approx 5' tall and used 6 - 1" dia tuyeres (3 per side) blown by a single "double lung great bellows". The end of the tuyeres were beveled back creating a gap. This gap would be plugged with a removable wooden wedge so that a probe could be poked through for cleaning slag away from the air inlets.
The entrance for the tuyere is carefully measured and placed at a 15deg downward angle.
The initial firing was done with a wood fire assisted by blowing air into the tapping arches.
The tuyere is in place and once again the surrounding earth is used for additional support.
Michael plugs a crack that developed during the smelt. While the clay had been "lightly fired" once the night before the structure did not have time do truely cure properly. Note that the tuyere manifolds have been covered in clay to stablize and seal them during the 9 hour smelt.
Darrell Merkowitz of L'Anse aux Meadows fame, answers detailed questions about his processes and smelter.
Seven hours into the smelt the clay had fully dried out and cracks rarely form. The flame type indicates CO is burning and the fire is "reducing". The tapping arch (lower right) has been opened and semi fluid slag has been pulled out.
Air was provided by a set of single lung bellows operated at a rate of 1 compression/second
Darrell adds an additional charge of charcoal and ore. By the time the smelt was complete the Norse smelter yielded a bloom weighing about 6#