Mounting Fire Based Activities
Considering Ground Surface Impact
Introduction
A physical demonstration of many crafts activities requires the use of high temperatures as a transformational method. Those involved with living history presentations have a secondary problem, as modern generated heat sources (torches) or containments (metal ‘fire bowls’) are obviously not historic methods.
Land owners may have established a ‘no ground fires’ rule. There are several underlaying (logical?) reasons :
- Not wanting surface lawns to be damaged.
- Not wanting to have pits dug into the ground
- Concern about transportation of fire wood, or gleaning activities
- Concern about potential dangerous spread of a poorly managed fire
- Concern about the liability aspects of burn injuries
Generally these concerns are expressed by three commonly stated rules :
- Only fires on raised metal fire bowls
- Only fires in specific pre-determined and equipped locations.
- No open fires of any kind
Event organizers need to be fully informed of the technical requirements related to individual craft methods. The physical size or working dynamic of a specific activity may itself impose limitations on how to properly and safely layout a fire based heat source. This is especially the case for historic demonstrations which will require the use of wood or charcoal fuel. A good example would be glass bead making, where modern practice is to use bottled gas torches the historic method is using a small enclosed clay furnace, charcoal fueled.
Often the response when contacting event Organizers, who may be constrained by simple rules dictated by land owners, is something like ‘You can work at the edge of the single shared camp fire.’ This is not a workable solution, as craft working requires considerable control of fire sources, if not specialized builds entirely. The desire for a companionable ‘fire circle’, or need for group cooking are just not compatible for the technical requirements for metals casting as one clear example.
There are a number of possible solutions that can be utilized by conscientious and experienced crafts workers that should fulfill at least the requirement for general safety and prevention of ground surface damage. Artisans need to explain these solutions in clear detail, Organizers need to understand physical requirements.
Contained Fires
Many historical craft techniques utilize fires inside specifically fire proof containers. Examples would be small glass bead making and metal casting furnaces. Larger and longer duration fires for ore smelting, pottery firing, even bake ovens, again all require durable containments. In all cases the purpose of these builds is specifically to hold the fire inside, concentrate and control these fires for correct function over time. Because of this technical requirement for fine control of heat, constant management of a very specific sized fire is necessary. In all these cases, the fires are normally contained inside clay or brick walled structures, and can not be in any way considered ‘open’.
Even the most extreme of all the potential fire based historic methods, bloomery iron smelting, requires a structure intentionally designed to withstand internal temperatures in excess of 1350 °C, over a day long operation.
Surface Protection
Often land owner rules will state ‘raised fire, just because this is the easiest description. It is expected that Organizers will be logical when considering the following long proven options for safety and limiting surface damage. The question needs to be considered : ‘How high does ‘raised’ actually mean?’
Iron Smelting Furnace built on concrete pavers preserving a grass lawn. At Western Michigan University, International Congress in Medieval Studies, 2013.
Smaller furnaces can be built on special purpose refractory plates, such as pottery kiln shelves, or even on slabs of thin stone.
Demonstration
of the high temperature Aristotle iron re-melting
furnace. This furnace is about 20 cm at the base, and safely sits on
a refractory plate. At a Society for Creative Anachronism event.
If absolutely
conserving lawn grass is a consideration, lay down a standard wooden
shipping pallet, then place the same concrete slabs on top. This
method was first devised in 2005, when a full iron smelting
demonstration was mounted on archaeologically sensitive ground
(Canadian National Blacksmith’s Conference at Annapolis Royal NS).
It has been used repeatedly to also conserve concrete flooring and
decorative lawns, and proven to have virtually no impact after being
removed. Positioning several lengths of 4 x 4 lumber will also leave a protective air space below the concrete plates.
For smaller furnaces, the same effect can be achieved by laying down a couple of cut to fit pieces of standard 2 x 4 lumber. In either case, and potential heat transmitted downwards through the fire proof plate is vented by the air space created underneath
Faced with the problem of not damaging archaeological ground in Britain, but still wanting to create a historic looking solution, the long standing living history group Regia Angolorum (back about 1990?) developed a protective design suggested by a panel from the Bayeux Tapestry.
In it’s simplest form this is a set of clay bricks, placed loosely on the ground, contained in a wooden framed box. These can be covered with a thin layer of sand, which both hides the more modern bricks and also will fill any gaps between bricks. The basic design can be improved by laying a piece of light sheet metal down first. More elaborate equipment is also constructed along the same principle, with use of short legs to lift the entire surface clear of the ground. This form is more commonly seen in European re-enacting, where the problem of not marring archaeologically significant ground is always present.
No details of who / where. The fire surface appears to be a 10 cm deep bed of sand seen to the left end. – uncredited internet source
These fire boxes, on the ground or raised, were introduced as a response to a specific problem inside a specific region, they are also being applied for cooking purposes only. A slightly smaller version may be suitable for supporting smaller furnaces (metal / glass bead work). These activities require quite specific heights for safe and efficient working. Again, physical transport needs to be considered, with table frames, crates of bricks and pails of sand.
It is worth remembering that the most common solution suggested, a completely modern stamped steel dish, is not suitable physically for containing a craft working furnace or kiln. What is required for any of this equipment is a flat supporting surface, not a depressed bowl.
Value of Experience
Organizers need remain aware of the value of the accumulated experience of individual Artisans. This may be considerable, and certainly any long working artisan will be fully aware of the operating dynamics of their heat sources and safety measures involved. Rather than applying a simple blanket rule, individual cases need full consideration. Organizers should never forget the considerable effort undertaken by Artisans, and the overall value any physical demonstration brings to their event.
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