Evolution of the Copper Oven
Signature Series by Maine Wood Heat Co. & Barry Norling
We built our first Le Panyol oven in our back yard about ten years ago. We knew we might want to move it around from time to time, to show it and share it with others, so we did not pour a footing, build a foundation or create an oven veneer or and oven structure or even a roof. Instead, Albie went to Dan Brown’s steel yard in North Anson and asked Dan if he had any large hand forged iron tire irons for sale. As hoped, Dan had a few in the field out back next to an old fire escape or two. Albie bought the largest one and brought it home. Dave Bentinnen of D&E Metalworks, who makes our steel dampers and by-pass channels, fitted the antique forged iron rim with a welded steel plate. Inside the wagon wheel rim, Dave added a six or seven inch tall thin steel collar to extend the rim height. We measured the circle diameter and transferred this measure to a dry layout of the four tile by four tile Terre Blanche hearth layout of the model 83 Le Panyol floor. With the tiles numbered and marked we cut each tile along the rim with our fourteen inch wet diamond saw and readied the tiles to be fitted inside the wagon wheel rim.
Directly on the welded base plate we laid in dry a 3 inch layer of block insulation, also cut to a circular form in several pieces. Over the years we have experimented with many forms of block insulation, including Foamglas which we learned will crack a good deal under high heat stress conditions. We also have used insulated firebrick and insulating castable refractory. Eventually we found a product line from Denmark called Skamol, which is widely used in the hearth industry. The standard product that many stove manufacturers use is a pressed vermiculite and waterglass board, but under wet conditions the pressed board could soften because waterglass (sodium silicate) is water soluble. Sodium silicate is the standard binder in most wet mix refractory mortars as well but again, because of its water solubility, it is limited in use to areas that do not get wet, such as a firebrick firebox. Eventually we started using another Skamol product, which is made of calcium silicate. This product has good thermal insulating and load bearing characteristics, is non toxic, and does not get soft when wet, although it does absorb a lot of water for a wet mix concrete or mortar application.
Traditional oven builders had no products like Skamol or foamglass or insulating firebrick available to them. Usually, sand was the material of choice used to offer some insulating, however poor, value. We have also seen wooden crib works of logs used as the base of hand made ovens. Covered with clay and sand, the crib works were both a support and a thermal break and did not ignite. Such crib works would not meet modern fire safety codes today.
On top of the block insulation layer we poured and tamped a 1.5″ to 2″ layer of Terre Blanche grog. The grog is the same kiln fired “white earth” that is used to make the hearth and orange slice (voissoir) oven dome sections. With the grog in place, each numbered hearth tile was set and tamped into place with a rubber mallet and mason’s level. On top of the circular layout of hearth tiles, we built the oven dome, starting with the lintel element set in just deep enough to allow the outer two piece lintel/smoke throat elements to be added at the end of the oven dome assembly. We supported each voissoir with a 12″ stick of wood and placed the cone section keystone in place to finish the dome structure. With the key stone in place, the oven was essentially self supporting and we could take out all the propped sticks inside, but first we added a double band of tie wire around the circular base of the elements and attached to two bolts anchored in either side of the one piece lintel element.
We added the front throat/ smoke shelf elements and our first stainless steel throat transition piece (manufactured by our sheet metal craftsman friend, David Belanger) so that we could exit from the throat with a standard American 8″ round pipe. It turns out that for smaller model Le Panyol ovens, a 6″ pipe is generally sufficient and we have successful installations of model l20 ovens using an 8″ pipe. The stainless piece was gasketed and tap con screwed to the oven lintel elements for a secure, tight fit. With a garden hose set to a spray setting we thoroughly moistened the oven dome until the creamy white elements turned a salmon pink. On top of the moistened dome we pargetted the proprietary Le Panyol mortar supplied with the oven core. The first portion we used to fill the gaps in the joints between the voissoirs. The second portion was plastered over the entire dome. We then attempted to create a waterproof stucco finish over the oven dome using standard masonry stuccos.
We set the oven carrying antique wagon wheel rim and plate on a red painted 3′ tall concrete well tile. For the annual Common Ground Fair, we wanted to be able to lift the oven up and carry it safely one hour away to the Fair Grounds in Unity, Maine. The wheel rim and plate projected just enough for us to approach the oven with a fork lift and nudge the rim, plate and oven at one edge up into the air, just enough to slip in a short 2″ by 4″ section. Coming in from the other side, we could lift the plate again and insert a second 2″ by 4″ shim, leaving us enough clearance to slip in under the wagon wheel rim and oven the entire length of the forks and to move it gingerly to our platform trailer where a secured pallet with a layer of 2″ styrofoam awaited the oven. We lifted the tile and secured it on the trailer without a pallet and then with quilts and straps tied down both the oven and the base.
Each year we tend to take a truckload or two and a trailer full of heavy gear to the Fair. Once we have it loaded we call Ray’s Garage and he picks up our forklift with his tow truck and meets us at the Fair. We unload all of our gear and park the forklift near the woods and reverse the whole process when the Fair is over. Amazingly, other vendors regularly bring timber frames, out door boilers, heavy stoves and other equipment but are rarely equipped with a forklift, so our unit gets a lot of requests for use during set up and break down.
The new oven traveled well and worked beautifully at the Fair, but the lifting, palletizing and strapping and loading and unloading were a lot of work. Ultimately, we made a decision to explore a new idea when we saw that the stucco skin wasn’t holding up well and the inner elements were going to suffer from water damage during freeze thaw cycles.
Albie came up with the idea of a copper skin and began to search all over for a gifted copper designer and fabricator. He eventually found a European immigrant in Florida who thought he could make a copper dome. Negotiations were under way when Albie remembered that not ten miles away, we had a copper sculptor friend in Norridgewock, named Barry Norling, whose specialty was custom made sculpted copper weather vanes. We called Barry and he came over and looked at an oven core dry stacked in the barn and said that he thought he could make an attractive weatherproof copper dome for our Le Panyol oven. He showed us his unique welded wire and brown paper design and templating system and soon had a template built for our model 83 dome.
Meanwhile, we were also researching the possibility of making the oven not only fully weatherproof, but also roadworthy on its own custom made trailer. A local family business, Nichols’ Trailers, had already made a 10,000 lb flatbed trailer for us that we were very happy with so we went to Nichols with our design needs for our oven trailer. We wanted a rotating base for the oven so we could land the trailer anywhere and turn the oven to the best side for the public present at that site. We wanted a removable tongue so people wouldn’t trip over it and so the oven landed would look more like a float with a canvas skirt around it, and we wanted springs that wouldn’t let the oven shake and bounce badly as we went down the road with it.
Nichols created the trailer we wanted and Scott Barden added a sustainably harvested teak like deck to the oven platform and Barry built our first copper dome, complete with a removable insulation fill cap on the top and a rain visor over the door and a smoke exit over the door that could receive Dave Belanger’s stainless throat transition and give us a collar to sleeve a removable smoke pipe through. When not in use, the smoke collar also had a waterproof copper cap. We left about two inches or clearance between the oven dome and copper skin and shaved off the front corners of the outer smoke throat elements so the copper skin wold slide over the dome. Lacking any special rim fitting detail, and still working without our original forged wagon wheel rim, we siliconed the rolled welded edge of the copper dome to the wagon wheel rim with clear silicone. Once secure, we poured in vermiculite in the limited gap between the dome and the skin. For the first firing, we left the fill cap off to vent excess moisture from the restored oven. For extra mass we had added a thin skin of castable refractory concrete on top of the Le Panyol proprietary mortar and the open cap and slow settling fire, allowed us to vent this excess moisture safely.
The new copper domed portable oven was a hit wherever it went. We took it to neighbor’s houses, block parties, small catered events and to the Common Ground Fair. Albie drove it twice to Rhode Island to bake pizza at special events held at the culinary campus of Johnson and Wales University in Providence.
It looked like an oven. It was aerodynamic and easy to haul. It was rain proof. It was shiny and said,
“I am copper, think food, think oven, think pizza, think bread.”