As a continuation of the ongoing experimental research under Neil Peterson, DARC mounted a combination demonstration and hands on session with a possible Viking Age bead working furnace. The furnaces are clay & horse manure construction, fire charcoal, and are based on 'possible' footprints suggested by the archaeology primarily from Ribe Denmark. For a more complete background, see Neil's published research.
|Overall view of the set up - inside the 'forge' duggout area|
|Working in the stack, heating new rod to apply decoration|
|Streaks are small pieces of burning charcoal in the vent|
Two primary problems are plaguing us with this specific design, which is based on the size of one of the uncovered 'base plates' :
1) Although high enough temperatures can be produced to effectively work the glass, the actual effective time is quite short. Our skill levels are mid level at best, and typically only one semi complex (base plus two colour patterning) can be created in one charcoal fill cycle.
2) Marred surfaces, from flying ash and small particles of burning charcoal are common, almost universal. Artifact beads do not show these effects as common. This strongly suggests we are doing something 'wrong'.
Our next prototype furnace is abandoning the profiles suggested by the artifact bases. Instead I have suggested a design based more on the dynamics of burning charcoal, gathered from experience working with charcoal forges. The concept is to contain the hot gasses to produce an effect more like a torch - then work inside that blast. (An earlier post describes this system.)
There will be a workshop this weekend at Wareham where a few of us will be working with a new prototype. Hopefully there will be a field report with some images later in the week describing the results...