First Firing in the Converted Gas Kiln

Pots in the kiln- some with homemade ash glaze made from red and yellow clays found on the property and hickory ashes from the fireplace. I dusted a few more ashes on them just to see what it would do by itself.

Kiln as it was set up for first firing. Always check propane connections for leaks with a bit of soapy water.

           With only a half a day drying time for the pieces I’d dipped in the ash glaze, I started the firing at 1 o’clock at very low flame, just enough to keep the torches from going out. About two hours later, I turned it up to a strong yellow flame and an hour on, to a loud blue flame. I heard no cracking or pinging from inside the kiln so everything seemed to be doing fine.

Warming up on low flame- 2 hrs

Turned up to halfway on the torches. The pipe elbow bottled up a lot of heat and probably restricted the flow despite the height of the chimney. Also, torches needed more room but backing them out made the flame erratic (I enlarged the holes for the next firing attempt).

After the 15lb tanks ran out, I increased the pressure on the 40lb one and tried to seal the second fire port with a brick. I turned it back again pretty quick...

          I had hoped to see cone 6 bending after four hours or at least five hours but the kiln seemed to level off and the small propane tanks kept running strong. Well, strong, they weren’t- the pressure change was so gradual that it wasn’t till I kicked one in the dark that the contents momentarily pressurized and suddenly the torches reminded me how loud they had been at first. I went ahead and shut off the right tank and unscrewed the line, substituting the new 40 lb. tank and relighting. All seemed to going well again and I alternated between reading in a chair by the kiln and carrying red bricks over to make a floor around the kiln to keep rain runoff away. Despite getting strong reduction flames out the chimney and later out every crevice in the lower 2/3s of the kiln, the cones all remained standing straight by 10pm (9 hours in) at which time I gave up and cut the valves to half and then off completely after 30 minutes. Total gas used was a little under 5 gallons from the 40lb. tank and 7 gallons between the two 15 lb. ones, so 12 gallons all told.

          I waited until the next afternoon to open the kiln and see how the pots had fared. The result was as expected; they were all well-bisqued but the ash glaze was just a dry flaky crust and the pure ash I’d dusted the rims with looked like burnt coffee grounds. The latter could be wiped off leaving a lightly brown stain.

         Well, that's the nature of experiments. Next- to figure out why it wasn't making it higher.

Electric to Gas Kiln Conversion

           Well, I finally made it out to get things on the gas kiln shopping list- propane, sabersaw blades, stovepipe, and firebrick. Two barbeque tanks from Sheetz and a narrow stovepipe with elbow, rectangular flange, hood/cap, and screw clamps came back in the car. A phone call and a drive to a local brickyard turned up forty heavy firebricks rated to 2500 degrees Fahrenheit.After warnings from friends that I'd need more fuel, I picked up a 40lb propane tank from Tractor Supply (I eventually tried to get a second but no luck- and I wish I'd been able to).

Electrical elements pulled out of the sides.

           Back at the farm, I cut the two torch holes in the bottom ring of the old electric kiln, then the slot between them for the exhaust/chimney. I tried to make the latter hole equal to the former two combined to balance the draft. I had already cut the old heating elements at the ceramic plugs in the wall and removed them- several broke on the way out, despite trying to be gentle. The straight pieces of wire that secured the elements were pulled as well. Next, I assembled and test-fitted the chimney, drilling a hole through the stovepipe about halfway for a piece of threaded rod. The rod had a nut at one end to hold it in a spring that was attached to the kiln’s lid hinge. The other end passed through the chimney and was secured with a wingnut.

Torches and stovepipe placement. Torches needed to be suspended outside the kiln so they could get enough air

           I carried the kiln sections, chimney, and bricks over to the ca. 80’ sand ring nearby and began to set it up in the center. I dug pockets into the sand down to the red clay below to seat four bricks that would give the kiln’s steel stand a stable footing. With all the fall leaves cleared from the ring, I set up the floor, rings, and lid, then added a cinder block behind and attached the chimney. The block would support the stovepipe and torches. The firebricks would hold the torches but I didn’t make them into a chimney, wanting to see how well the pipe worked first.

First incarnation, minus gas hoses.

           With rain forecast for the next day and a package of Seger cones only due to arrive the day after, I found four old 4x4s and some boars and rigged a simple frame over the kiln, eight feet high. This I covered with three sheets of galvanized tin roofing after another run to Lowes. I left the sheets loose in case the heat got too high and I needed to pull it off but the stovepipe didn’t do much more than warm the boards in the end.

           Kiln packing was simple as this was mostly to be a bisque firing- I stacked the more fragile and smaller things inside the larger, and made sure to turn jugs and other handled forms so their handles pointed inward, out of the direct path of flames. I threw some play sand between the nested pieces and tried to keep the like-clays together lest things get stuck together/melt. I had pieces made from five different clay sources in the kiln, several of which I dug myself, so I didn’t know what to expect.