Second Firing .... April 3rd, 2000
Kiln Log Book
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Hopefully we had learned a lot from the first firing .... a lot about wood, about stoking
rhythm, about loading, etc. For our second firing one of the issues we wanted to work on was the apparent imbalance
of heat within and between chambers, another was everyone's desire for some more ash deposit.
In an attempt to address these issues we rebuilt the first chamber bag wall to open it up to allow
flame to draw across the kiln floor more easily and hopefully allow more ash to deposit. The first firing used
mostly discarded construction materials which did not produce the heat or ash we desired, the second firing used
"real" wood (split down to forearm size) and cedar shingles. We hoped the combination would give us better
heat and ash ...
This firing we would be able to "salt" the second chamber as the first firing had set the
ITC coating. Rather than use the standard table salt (which is extremely hard on the kiln surface), we decided
to get the sodium vapor another way. After some research we decided on a mixture of bicarbonate of soda (baking
soda) and water which would be sprayed into the second chamber stoke holes at regular intervals. We used about
three pounds of baking soda mixed into a large garage-sale pressurized garden sprayer to produce the sodium vapor.
Our plan was to load on Sunday, fire Monday, and open the following Friday. We had left some glazing
to the last minute and were applying glazes as we loaded the pieces into the kiln. We loaded the salt chamber first
and realized, after it was about half loaded, that we had packed it too tightly and now we hadn't enough pieces
to continue the same packing density. We put in a lot of re-fire pieces to take up the slack, but the load was
not well balanced at the bottom. That in addition to the large, open pieces on the upper shelves would hamper us
later in the firing.
The firing crew was basically the same as the first firing ...
Don, May, Tea, Don, Bob, Beth, Richard, and Diane. We used propane overnight to warm the kiln and help with initial
draw. We started a fire in the main firebox at 5:30AM using some ceremonial chopsticks from a going away party
we had had for a fellow potter from Club Mud.
To improve ash deposit one of our goals this time was to spend more time "fluffing" the
fire bed in an attempt to get more ash into the air early in the firing. The cedar shingles were excellent in producing
a light ash that we could easily get airborne. For as long as we stoked the main firebox we would fluff up the
coals on a regular basis.
The firing went well and it appeared our changes had improved the flame path and heat distribution;
however, the poor load balance in the second chamber resulted in the back-bottom never getting up as hot as the
other parts of the kiln despite our best efforts.
The kiln stalled at around cone 9(ish) and we struggled for a few hours (even splitting wood at 9:30PM)
to get the temperature up in the second chamber, but finally at midnight we agreed that we were about as hot as
we were going to get and shut down. Before leaving we mudded up the peeps and stoke holes, moved any remaining
wood away from the kiln area, and prayed the kiln gods would reward our efforts ...
On Friday morning the excitement level was high. The firing crew and assorted friends arrived by 11AM
to open the kiln, those too anxious to wait for everyone started by chipping the mud off the kiln doors and clearing
the area to stack the shelves and bricks. With the toss of a coin we decided to open the salted second chamber
first and were rewarded with wonderful (no fantastic!) pieces. The new salting technique had produced an extremely
nice effect on all the pieces and everyone was ecstatic at the results.
By the time we had unloaded both chambers we had two plus tables full of excellent pieces. The wine
flowed, the congratulations were extensive, we took time to enjoy the success of our many months of labor and began
to plan the next firing (June 2000)
...
