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Bead Furnace Burn Jul 18 2009



Creator: Neil
Materials: Cobb (Manure, clay), charcoal, glass
Location: Treheima
Notes: Used blower, small number of experienced beadmakers, lots of video and temperatures


This was the second use of the oval mark V. The base is a 30x60cm oval matching one of the bases found at Ribe. This style can be set with two working ports - one on each short side. The port for the bellows is in the center of the long side. Opposite that port is a chute for loading charcoal currently blocked with a crucible for annealing. At the top are two chimneys with another pot for annealing between them. The chimneys were built a bit smaller than the mark III and the annealing pot a fair bit deeper.

We filled the annealing pot with sieved ash and got some good annealing temperatures in that location. The crucible was rather too warm for annealing this time.

This melt was targetted at a smaller group of experienced bead makers. This allowed us to spend more time making beads, learning more about working with the tesserae, and eliminating one variable (skill) from the annealing problem. We also got some good pictures and video of the activities.

Scaled Drawing Fire zones Turning Reticella Heating tesserae
Winding on tesserae Working in the chimney Marvering for shape Marvering
Pulling stringers Working multiple beads Putting beads in the annealing pot Adding decoration
Taflmaðr Darrell's better beads (and taflmaðr) Rob's better beads Jean's better beads
Maintaining a useful temperature is HARD in these furnaces. A charcoal load gives time to make a single bead at each side. Tiny changes in the direction of air inflow can make big changes to the heat locations inside the furnace. This time we would up in a decent pattern

A type K thermocouple was employed to roughly measure exhaust gas temperatures at one of the top ports over the experiment. A roughly 6 mm (1/4 inch) diameter hole was drilled into the wall of the furnace, just down from the lip of of the port. The probe was extended into the opening about 1 cm. Although the probe was placed early in the experiment, and readings were constantly monitored, unfortunately the recorded data currently extends over a relatively short time sequence. Since the thermometer was included in the frame of the overview video shot we will be able to extend this table when we have time to analyze the video in depth.

TIMETEMPEVENT
1:03900 
1:041000 
1:07900 
1:09700 
1:10800 
1:11 charcoal fill
  change method
1:15755 
1:16655 
  adjust charcoal
1:17925 
1:18810 
1:19850 
1:20890 
  adjust charcoal
1:21910 
1:22830 
1:23860 
1:24870 
1:25840 
1:26850 
1:27820 

We confirmed that Darrell's tesserae method worked repeatably. It is unlikely to be the only usable method but it can work and we have some good video of it

A video of working with tesserae can be seen on youtube

      Updated: 8 Jul, 2009
Text © Neil Peterson, 2009
Photographs © Individual artists
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