Future site of kiln before ground-breaking
Kiln site excavated...much easier soil to dig compared to North Carolina red clay. Bourry-type firebox will be located in the foreground followed by a (sprung-arch) chamber (2 total; one on each terrace) and the flue and chimney on the uppermost terrace. The first chamber will be unglazed wood-fired work (cone 9 to 11). The second chamber will probably act as the spark arrestor (along with a stainless steel mesh at the top of the chimney). This second chamber will have cone 6 glazed ware. During the rainy season, this chamber will be sidestoked and soda-fired (cone 8 - 9).
Kiln site excavated (Early Oct. 2010)...more photos to come in January. Materials are on order, including cinderblock and materials to build a shed over the kiln site
Me for scale, plus a break
Kiln site excavated (Early Oct. 2010)
Break for the snow
Bracing for the cold
Some of us deal with the cold better than others...it's a tough life for Oscar.
Designing firebox floor as it steps into the main ware chamber
Setting cinderblock with a mix of concrete and fireclay. I scored the surface of the wet mix to hold the levelling sand layer onwhich the firebrick will sit.
Ready to lay firebrick
Mixing mortar and setting refractory cinderblock and firebrick
Figuring placement and setting the "stairstepping" grate system and airways for the floor of the Bourry box
Ramping of block; not only helps flame ride up into the main chamber, but also allows for a triangular-shaped sagger space beneath
Refractory cinderblock walls go up as well as the beginning of the chimney. Concrete cinderblock is used as supportive shell for the interior veneer (hotface surface), which consists of firebrick and heat-set mortar
Cross-sectional view of the vertical stack. Notice the interior hard refractory brick. Photo also shows 1 of 3 built-in spark arrestors (1/4" square stainless steel mesh) that will be installed in the chimney
I have the option of inserting steel bars to act as an "elevated" grate if I feel that it is necessary to get more air circulating under the wood. My primary solution for a grate is to build 2 small arches on the floor of the firebox (see photo below) instead of the use of customary hobs for a Bourry box
View inside the main chamber looking back through to the firebox
My apologies...steady progress and dealing with the cold aparently interfered with my photo documentation. As you can see, the arch is in place. The kaowool, as well as every bit of brick is recycled, primarily from the demolition of my old "Train-kiln" which was located in Raleigh, NC. 22,000 lbs. of brick were loaded into an commercial cargo truck and hauled 1800 miles to Golden, CO. I have figured that I hauled around 55,000 lbs. from our driveway to the kilnsite. I had to carry all of the brick and gravel in two 5 gallon buckets, because nothing else could make the climb up the slope of our backyard. This does not include cutting and splitting a great deal of beatle-kill pine trees and dead aspen. At least I am saving from having to buy into a gym membership
3-4 inches of kaowool insulation in place, along with the support covering of wire mesh. This mesh is stong enough to support the "adobe" slurry that will be spread over the entire kiln. It is important not to matt-down or compress the kaowool fiber. The thicker and "fluffier" it is, the better an insulator it will be
Looking at the front view of the kiln. Notice the wire mesh is anchored (wrapped around) 3/4"x 4' black steel plumbers pipe housing the 2 steel cables and 2 stainless steel straps tightened with marine grade stainless turnbuckles (aluminum can melt). The strapping, along with 1" angle iron at the kiln corners, help brace and support the walls and arches during temperature rise (kiln expansion)
Same front view but with "adobe" coating. The kiln not only takes on a look of homogeneity, but also makes the kiln relatively air-tight. This feature will allow me much better control of the atmospheric fluctuations during firing. As cracks and chips occur, they can easily be patched, even while firing
A view of the arched floor grates as mentioned earlier. The angled block (also mentioned earlier) have been temporarily removed for the construction of the arch
Burners set on a removable brace. These burners are used strictly for the purpose of "candling" the kiln so that I can get some sleep before I begin stoking with wood early the next morning. The main chamber can reach a temperature range between 700-1200 F at daybreak. This not only allows me to have a headstart and easy ignition of the first wood, but also preheats the ware to allow for the direct contact with flame produced by the first stoking of wood.
View of the back of the main chamber as it steps up into the flat-top flue chamber. I will leave a sidestoke area at the base of the step.
Finished chimney stack with fabricated six feet of a galvanized, tapered extension (should have spent the extra money for a stainless steel extension that would resist corrosion...next time). Total height of rise from the floor of the firebox to the top of the chimney is 17.5 feet. The tapered extension, height of the chimney as well as the 30 degree sloping kiln site should provide ample draw. It is better to have too much draw than too little. I can now control this with passive dampers, and a physical sliding damper.
View peering inside primary (first) chamber. Notice the 9 inch thick (all hardbrick) walls. This kiln will take some time to reach temperature, but will also cool slowly, allowing time for some micro-crystalline structure within the natural ash drips and glazes.
Exposed chambers (firebox to the left, primary chamber to the right) showing the demolished arch support. The doors were too tight to remove (and therefore, salvage) the forms.
View of the ware loaded in the primary chamber. Many are resting on seashells on their sides.
Both firebox door and primary chamber have been sealed. Notice the 6 brick cluster protruding from the firebox door. These have been wrapped in clay-slipped newspaper. They are softbrick that will be used to as the stoke hole block. They can easily be pulled, and will remain cool to the touch on the handling end. Once again, notice the straps and cables that wrap around both the firebox and primary chambers. These cables/straps are also enclosed in black metal plumbing pipe to protect from the elements, especially from direct flames that will be constant from the removal of the stoke hole block.
View of the kiln from the roof of our house.
Another perspective from the roof top.
Final addition; a 1/8 inch capping arrestor constructed from 2 pieces of 1/4 inch stainless wire mesh fashioned so that the squares overlap.
Chimney cap spark arrestor
Chimney cap spark arrestor in place with support cables. The winds at the kiln site can reach gust speeds of 50-70 mph. These support cables will also help stablize the 6 foot galvenized stack extension.
This is the amazing view of Coal Creek Canyon from the kiln site. I could not ask for much more.
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