mel jacobson on sat 8 jan 05
many folks make many assumptions about
cones and there use. often wrong.
cones are a guide. the number one helper
for knowing when a kiln is done.
you learn your kiln and how the cones react
over time. it is not a simple `cones are down, kiln
is done`.
time and temperature are what makes glazes work.
cooling as we are finding out is very important.
long firing vs. short firings.
quick cool vs. slow cool.
all make a difference.
it is not what cone is bending, but how long
has the kiln been on, what is the atmosphere,
and how quickly is the kiln rising in temp.
john britt has helped a number of you with this.
very important stuff. his book information is critical
in this area.
what people say is cone 10, may not even be near that.
as i have said before...i remember the first time i visited
ken ferguson and he had just fired...he said...`damn good
cone 10 firing`. i picked up some old cones at his kiln
and ten was melted. it was cone 12 at the least.
(i learned a lot that day in 1966.)
wonderful glaze surfaces, but surely not cone 10.
i have fired with folks that have turned the kiln off when
cone ten was at 1 o'clock. that is barely nine. cone eleven
is just a few minutes melting after cone 10 is down.
in fact they often fall at the same time.
some folks fire a kiln for twenty hours. cone ten just barely over.
sorry, they hit cone 12 inside. the glazes are all shiny.
they say...`we fired to cone 10`. we do not have all the correct
information.
i find it very important to fire my kilns for at least 10 hours.
i keep the kiln held back for part of that time.
i like cone 11 half over.
cone 10 is just hitting the shelf.
i try for that each time i fire. oxyprobe at .05. and, i keep
it there for the entire firing. (from about cone 08 on.)
the joe koons glazes i fire hotter, and hold the kiln
back a great deal. it is very fussy. my kiln wants to fly
into reduction at a moments notice.
so, the cone is the same, time is the same, atmosphere is the
same. pots should be close to the same. i call it strong cone 10.
but, wind, temperature, humidity, barometric pressure all
play a roll. and of course how you pack the kiln does a great
deal to ruin or save a great firing. i am more and more packing
loose firings. save those pots for the next firing.
i leave a full inch between pots, and often 4 inches between
shelves...and stagger them at four inches.
i hate heat dams. and people still tell me how they
got 126 pots in a kiln that only holds 75. so they
ruin 35, it does not seem to register.
ruined pots is the biggest waste of fossil fuel anyone can
imagine. i go crazy thinking of folks that would never throw
away a soda can, and can ruin a 12 hour gas firing....over
stupid ideas. `but mel, i got so many pots in the kiln...that
makes me proud.` bullshit.
consistency is still the greatest helper for the crafts person.
doing the same things, same way, same timing.
that is why early in your life you do a great deal of charting.
but, then, charting without changing and thinking is just
book work. i never chart anything. i have done that.
i know how the kiln works. i know the timing i want.
why would i write all that down? waste of my time.
but, if something does not work....i change things around.
fast.
it is like the call i got...`mel, my kiln stalls at 1800F. what should
i do?` `how many firings have you had that the kiln stalled?` `103 over
16 years.`
click. my hands curl around the 2x4.
mel
From:
Minnetonka, Minnesota, U.S.A.
web site: my.pclink.com/~melpots
or try: http://www.pclink.com/melpots
new/ http://www.rid-a-tick.com
Ivor and Olive Lewis on sun 9 jan 05
What Mel says explains why we do not rely on one single cone.
We employ a cone pack with a Signal, a Mark and a Guard.
If you fire your Guard Cone down to a puddle of glass you have
ventured into "no man's land"
Get the blanket to repair the kiln this week. A load of birdbaths to
fire and lots of clay prepared for the trials with Talc Wollastonite
glazes on dark clay
Best regards to all for the Year of the Rooster
Ivor Lewis.
Redhill,
S. Australia.
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