The Great Kiln Wrap of 2008  2y clive tucker

It’s been a full year since ] moved into my
new studio, Straight Up Studios in Port Moody
with fellow potter Jacqueline Sheridan. Now
I can reflect on the progress and joy of setting
up my own space.

The kiln was by far the biggest problem
we had to solve. When we first saw the space
there was a big, fat electric cable hanging out
of the ceiling. It was a sign. This space was
meant for a kiln.

It was a big cable at least 60 amps, two
wires, red and black, it looked like a 240V
single phase supply. Brilliant, we had been
given a 240V single phase electric kiln. It
was a 10-cubic-foot oval from Seattle Pottery
Supply, rated at 48 amps.

Well nothing is quite what it seems, it was
indeed a 60-amp-cable but the supply was
three-phase and the voltage 208V. There are
plenty of three-phase kilns; the Vancouver
school board has three-phase 208V, so I figured

we could just convert it. Three-phase makes

no difference to the efficiency of the kiln; it Wrapping the front of the "free" kiln.
just needs to be wired slightly differently.

Next there was the voltage to consider, 208

V vs. 240V. The trouble with 208V is that it

doesn't deliver as much power as 240V. Power

9 e = Current (amps) X Voltage (volts). The kiln

Greenbarn &§ Ca ls was 48 amps x 240 volts = 11520 Watts. We
, ° | | le | ° had 48 amps x 208 volts = 9984 Watts

now Oo ° ‘This was only 86% of what we needed. The

solution was to call Seattle Pottery Supply and

(oe) buy a complete set of new elements for a 208

volt kiln. I installed them and we were ready

In an effoct to be move erwivonmentally to fire.

i ? by veducing our use of | , We ‘The first fring had 20 mugs in it with lots of
ave i out cue printed catalog, kiln furniture and nine sets of cones, it was a
Verslory glaze firing going to cone 6 and we wanted to

available on our website. map the heat distribution inside the kiln with

cones on three levels at each end and in the
(oe) middle. I had also installed a kiln controller

so the kiln was programmable.

Now you car check prices and item. The kiln was set to fire at 150°F/hr to 2195°F
descriptions just by logging onto and soak for 15 minutes. It was scheduled to

go off at 12 p.m. I arrived at 10 a.m. to log

WWW. gceenbarn corn the temperature rise of the last two hours of
e ‘eo

firing. At 2000°E, the rate was 70°F/hr. As the
temperature crept up the rate slowed even

further. At 5 p.m., I turned the kiln off. Some

anne ] Bret 39 r fe C| \ Tuesday Fiaay at of the cones were down but the rate had fallen
urrey, B.C. (| b aturday 9- : °F/hr. H : fix thi
\) Phone: 604,888.34] 1 IC Closed Long Weekends ce 20°Fihr: How were we going to Bx this
@ Fax: 604.888.4247 POTTERS SUPPLY LTD. greenbam@telus.net m

Continued on Page 5, Heat Balance

COLUMBIA Potters Guild of BC Newsletter - November 2009 4