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Overview
May 30, 2009
Nov 8, 2008
Oct 12, 2008
Jun 14, 2008
Apr 13, 2008
Oct 27, 2007
Oct 8, 2007
Jun 10, 2007 - Excav.
Jun 9, 2007 - Second
Jun 9, 2007 - First
Nov 5, 2006
Sep 1-2, 2006
Jun 10, 2006
Jun 10, 2006 - Tools
Nov 4, 2005
Sep 1, 2005 - CanIron V
Jun 11, 2005
May 14, 2005 - OABA
Jan 14, 2005 - Consolid.
Oct 24, 2004
Jun 3, 2004
Jun 3, 2004 - Design
Jun 3, 2004 - Questions
May, 2003 - Analysis
May 2003
May 2002

Iron Production Experiment - Sep 2005

Date: 1 Sep, 2005

Location: Annapolis Royal, NS

Premise: All proper equipment, done in costume. The presentation at CANIRON 2005.

Experiment Notes - Norse Short Shaft Smelter

The Team:

Leader Darrell Markewitz
Staff Kevin Jarbeau
Dave Cox
Mark Pilgrim
Recorder Neil & Karen Peterson

Smelt_cd Reports of all of our iron smelting efforts along with more articles and information are available on the "Iron Smelting in the Viking Age" CD from the Wareham Forge.  Copies of the CD can be purchased here.

Setting up the smelter:
The majority of the stage dressing was done the day before the smelt (Aug 31). The presentation included a norse tent as a background, a "sand table" forge, displays of tools, a table with displays of previous results and handouts, and the actual smelter and tools required for the planned smelt.

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Mixing cobb to build the smelter Patching flaws Rocks around the outside Reverse view
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Where the tap arch will be On the back - tuyure location Smelter from above Quick discussion of plans

The day of the smelt dawns anything but bright and sunny... Rumour was that this was pushed in by Hurricane Katrina. The good news was that it cleared out by lunch and the day turned out lovely, although some sunburns did occur.

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Sand table forge Removing the inner form Hole for the tuyure Mark on the bellows
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Darrell receiving some advice Kevin's turn on the bellows Adding the charcoal Darrell lectures Dr. Wallace
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Spreading the ore Pumping bellows is exhausting Checking the tap arch Jake helping on bellows
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Connecting the air Checking the airflow Flame from tap arch Slag running
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Charcoal scooped out of the smelter. Chipping the bloom free. Dave removes the bloom.
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Reducing the bloom. Compression drives out bubbles and slag. Crowd watching the pounding. Pulling the bloom again.
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More consolidation. The final result (before theft) Movie of extraction
The morning after
As usual we deconstructed the site the morning after the smelt taking a variety of measurements to assist in our experiments.

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Several shots showing the placement of the tuyure and its inlet for air inside the smelter. A look at the slag adhesions
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The wall changes colour multiple times Various grades of product Bit of the bloom


Time  Event Measures
Relative Absolute Total
Relative Elapsed Charcoal Ore Sand
0:00 00 addition rough charcoal, occasional gentle air blast (begins at 1120h)          
0:32 32 first graded charcoal added          
0:45 13 charcoal 1 4 lbs* 4 lbs    
1:02 17 charcoal 2 4 lbs 8 lbs    
1:22 20 charcoal 3 4 lbs 12 lbs    
1:40 18 charcoal 4 4 lbs 16 lbs    
1:42   seed charge 1 .75 lbs*   .75 lbs  
1:58 18 charcoal 5 4 lbs 20 lbs    
2:00 18 seed charge 2 .75 lbs   1.5 lbs  
2:19 21 charcoal 6 4 lbs 24 lbs    
2:21 21 seed charge 3 .75 lbs   2.25 lbs  
2:46 27 charcoal 7 4 lbs 28 lbs    
2:47 26 seed charge 4 .75 lbs   3 lbs  
3:06 20 charcoal 8 4 lbs 32 lbs    
3:09 22 seed charge 5 .75 lbs   3.75 lbs  
3:32 26 charcoal 8 4 lbs 36 lbs    
3:32 23 seed charge 6 .75 lbs   4.5 lbs  
3:49   sand 1 1 scoop      1 scoop 
3:58 9 sand 2 1 scoop     2 scoops
3:58 26 charcoal 9 4 lbs 40 lbs    
3:59 27 seed charge 7 .75 lbs   5.25 lbs  
4:16 18 charcoal 10 4 lbs 44 lbs    
4:17 19 sand 3 1 scoop     3 scoops
4:17 18 seed charge 8 .75 lbs   6 lbs  
4:40 24 charcoal 11 4 lbs 48 lbs    
4:43 26 sand 4 1 scoop     4 scoops
4:43 26 seed charge 9 .75 lbs   6.75 lbs  
5:07 27 charcoal 12 4 lbs 52 lbs    
5:07 24 sand 5 1 scoop     5 scoops
5:08 25 seed charge 10 .75 lbs   7.5 lbs  
5:51 44 charcoal 13 4 lbs 56 lbs    
5:55 48 sand 6 1 scoop     6 scoops
5:56 48 seed charge 11 .75 lbs   8.25 lbs  
6:42   Changed to Electric Blower          
6:46 55 charcoal 14 4 lbs 60 lbs    
6:46 51 sand 7 1 scoop     7 scoops
6:47 51 seed charge 12 .75 lbs   9 lbs  
6:54 8 charcoal 15 4 lbs 64 lbs    
6:55 8 seed charge 13 .75 lbs   9.75 lbs  
6:56 10 sand 8 1 scoop     8 scoops
7:03 9 charcoal 16 4 lbs 68 lbs    
7:11 8 charcoal 17 4 lbs 72 lbs    
16 ore charge 14 1.5 lbs   11.25 lbs  
7:20 9 charcoal 18 4 lbs 76 lbs    
ore charge 15 2.25 lbs   13.5 lbs  
19 sand 9 1 scoop     9 scoops
7:30 10 charcoal 19  4 lbs 80 lbs    
ore charge 16 3 lbs   16.5 lbs  
sand 10 1 scoop     10 scoops
7:42 12 charcoal 20 4 lbs 84 lbs    
ore charge 17 3 lbs   19.5 lbs  
7:52 10 charcoal 21 4 lbs 88 lbs    
ore charge 18 3 lbs   22.5 lbs  
8:01 9 charcoal 22 4 lbs 92 lbs    
ore charge 19 .75 lb   23.25 lbs  
8:03    reduce air flow          
8:10 9 charcoal 23 4 lbs 96 lbs    
8:22 27 reduction charge 20 .75 lbs   24 lbs  
8:22 12 charcoal 24   100 lbs    
8:35 13 charcoal 25   104 lbs    
8:42   reduce air flow          
8:45   reduce air flow further          
8:47   air flow reduced to minimal - remaining charcoal removed          
8:52   consolidate bloom with wooden thumper          
9:02   remove bloom and consolidate          
9:06   return bloom to smelter          
9:11   remove bloom and consolidate          
    return bloom to smelter          
    remove bloom and consolidate          
    return bloom to smelter          
    remove bloom and consolidate          
    return bloom to smelter          
    remove bloom and consolidate          

NOTES:
Charge times recorded at END of unit addition

*  All charcoal charges are based on a 'standard pail' - weight of 4 lbs 
All ore charges are based on a 'standard scoop' - weight of 3/4 lbs
All sand charges are based on a 'standard scoop' - weight of ??? lbs
  Estimated from known marks

YIELD:  5 lbs (estimated)

Our presentation at CANIRON was a partial success.

As a smelting history demonstration, it was excellent - and very well received. The fact that equipment problems and substitutions put us into early evening for the bloom extraction made the showering sparks extremely impressive.

Dr Brigitta Wallace was an observer for most of the day long smelt - plus for the forging contest the next day. As with other archaeologists who have seen us at work, she felt she had a much better understanding now of how the physical remains relate to actual process.

What happened:

Slag
We used the pure taconite ore, which has almost no silica in it
We researched and used a commercial high temperature clay for the smelter walls, no melting means no silica.
No silica and no silica means NO SLAG. No slag means no carbon control.
We thus (predictably) produced a block of CAST iron.
Although an attempt to create more slag via addition of beach sand - this was done on the spur of the moment and without real science. With some thought we should have been able to run the numbers on this.

By the way - the finished bloom mass was stolen late the night of the smelt. We have one tennis ball sized fragment. With image evidence we should be able to guess the total weight from the fragment - but really do not have any yield measurements.

Air
The large bellows continues to create problems. Modifications to the bag and plate construction, new handle shape, new frame - all made these physically easier to use.
There remains a problem with air delivery. Right now there is no downstream valve set up.  We think what happened is that as soon as slag / sintered ore started to obstruct the tuyere, we actually were pushing air from one chamber into the other as much as pushing air to the smelter. Simple flap valves should help with this. With use of a mechanical air system - the reaction kick started almost immediately.

Lesson Learned: we should make sure we have a mechanical system on hand regardless. A hand cranked blower at least.

Kevin points out (via his reading of Pliener):
Historic iron production sites often show three or four types of smelter construction - one each. Then there will be dozens (or hundreds) of one of these styles. Likely explanation is that they tried a couple of different set ups to utilize local materials. Once something worked - they duplicated that over and over. Ore / clay / smelter shape /  charcoal /air system all fit together to produce a 'best possible' combination. Our major problem is that we keep changing multiple variables almost every time. If you look at the smelts with good results - you see they are times when only one (or two) variables are changed.
Smelt_cd Reports of all of our iron smelting efforts along with more articles and information are available on the "Iron Smelting in the Viking Age" CD from the Wareham Forge.  Copies of the CD can be purchased here.
      Updated: 4 Dec, 2007
Text © Neil Peterson, Darrell Markewitz, 2007   Photographs © Individual artists   Copyright details
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