Date Started - June 2004
Date Completed - Estimated Public Debut - June 2005
Sources: "Early Irish Ironworking" by B.G. Scott; "The Celtic Sword" by Radomir Pleiner; Viking wood carving from the Sigurd Church Portal, Hylestad, Setesdal, Norway; Assisted with reproduction smelter of same style - Metalworking Symposium October 2004
Notes: This smelter style, while in use on the European continent since ~ 100BCE and used by the Norse ~500CE, was finally adopted by the Irish ~ 900-1000CE. This smelter uses a set of twin single lung bellows worked in alternation. Fueled by charcoal, the smelter and portions of the tuyere are made from clay. The original ore type was typically "bog iron" (limonite), but depsite our best efforts we have been unable to locate a local source. Fortunately, we do have a high quality source (assaying shows 98% pure) of magnetite ore near Port Henry, NY.
Typical charge size is 15#-20# of ore. Estimated bloom result ~5#
03/13/05 - Neo Irish/Norse test smelt. Assembled a smelter of the same type as the final project. This smelter used modern materials but only those that could be reverse engineered back to period materials. The purpose of this smelt was to test tuyere placement, tuyere construction materials, and over all functionality of a smelter of this size. A blower was used in place of bellows but care was taken to assure that maximum output could NOT exceed that of hand bellows.
Crushed hematite ore. Total quantity used to charge the furnace was ~80#; much larger than the original estimated amount that this style of furnace was capable of smelting.
But the flue tile is too thin in it's current state to retain heat, so a 1" thick layer of clay and cellulose insulation was added.
Checking the furnace for level. This seemingly minor point can drastically affect bloom formation. Major problems can occur if the ore falls straight down a crooked shaft.
Initial preheat. Simple wood fire under blast was used to preheat and dry the outer clay covering.
Well under way the furnace has developed some cracks. But the slag is flowing well from the tapping arch and ore is still able to be added at the max rate of 3# per charcoal bucket.
Terra Cotta flue tile. The use of the flue tile allowed us to quickly construct a stack without having to make clay blocks. When the period edition of this furnace is made, the clay will be mixed with straw and other 'organics' and then made into blocks, eliminating the need for step 4.
An intermediate layer of chicken wire was used to stablize the "clay" mixture.
Sighting tuyere placement. Another critical issue is the placement and angle of the tuyere. In this case the top of the tuyere was sited to a point 4" from the bottom of the oppsite wall. This yeilded ~20 degree angle.
Preheat completed and furnace filled with charcoal. Once the charcoal was ignited the first seed charge of ore was added (~.5#)
Thick clump of slag is being re-added to furnace. This slag was iron rich (as evidenced by sparklers when it flowed out) and is being reprocessed.