Mary Molinaro on thu 5 jun 97
>Subject: Kiln Soaking
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>Help please! How exactly do I go about soaking at ^5-^6 electric without
>overfiring? I've gone from a 3.5 cu.ft. to 7 cu ft. kiln and I'm finding
>it fires faster/hotter, resulting in bubbled glazes and clay. It has 3
>separate element switches: low - med - high on each switch.
>Thanks.
>
Louis Katz on fri 6 jun 97
1. Try firing off the kiln with all switches on Medium
2. If that doesn't work try 6 hours with the bottom switch on High
3. If that doesn't work try the top switch on high also.
If that doesn't work I am not sure what to offer you as an easy solution
other than leaving more spy holes open.
Louis
Louis Katz
Texas A&M University Corpus Campus
lkatz@falcon.tamucc.edu
http://www.tamucc.edu/~lkatz
Karen Gringhuis on fri 6 jun 97
Dear Mary - It helps greatly (is critical to me) to have a digital
pyrometer. (See the Bailey catalog & talk to me more if you
decide to go this route.) When I get the cones almost over, I turn
the middle burner from 11 down to 10 & the top from 12 down to 11.
I try not to lose much temp but have over 2 hrs. lost as much as
20 degrees. This stalls the kiln for as long as I want.
How you manage this with only low-med-high settings on the
burners, I don't know but maybe turn down the middle only.
If you have no trouble getting to top temp, maybe get there more
slowly. (I fire C/9-10 so I put top & bottom on high w/
middle on 11 when I turn the kiln on initially - so I get to
temp efficiently.)
As an aside, I fervently recommend a digital pyrometer. If
all my cone packs fell apart I could fire by the numbers
if I had to. It also gives me a great track record of each
firing & I could see when the elements were on their death
bed by the elapsed time, etc.
Good luck Karen Gringhuis
Ron Roy on fri 6 jun 97
>>Help please! How exactly do I go about soaking at ^5-^6 electric without
>>overfiring? I've gone from a 3.5 cu.ft. to 7 cu ft. kiln and I'm finding
>>it fires faster/hotter, resulting in bubbled glazes and clay. It has 3
>>separate element switches: low - med - high on each switch.
>>Thanks.
There are three ways of soaking and they all have a slightly different
effect on glazes. Which one to use depends on what you are trying to do. In
all cases you need to watch you large cone go down - cones measure time and
temperature (heat work) so they are always the best policy. I recommend
having them in different parts of a kiln - excellent indicators of what
happened so you can make adjustments.
1. Slowdown as you approach your top temp. This is useful when your kiln
fires unevenly - to slow down turn one switch down - the one that heats the
hottest part of your kiln. This is not the best soaking for eliminating pin
holes. Watch your cones and/or your pyrometer.
2. Try to maintain top temperature by turning down your switches enough to
prevent further rise - tough to do unless you have a controller. You will
find a pyrometer very helpful. The cones will drop quite quickly compared
to #1.
3. Getting to temperature (cone starting to bend) and turning down your
switches enough so the temperature falls slowly. This is the best kind of
soak to get pinholes to seal over - of crawling isn't too wide it will help
the glaze get together.
Fast firings are uneven usually - slower firings - particularly at the end
- are more even. A rise of 50C per hour or less for the last 200C will help
even out firings, improve glaze quality and allow a better glaze/clay bond
to develop.
If uneven firing is a persistent problem and you need even firings I
recommend the Orton controller with two pyrometers. The controller will
then send extra heat where needed. My firings are now perfectly even from
start to finish in my electric kiln.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/ronroy.htm
David Woodin Set Clayart Digest on sat 7 jun 97
If you have switches that are low medium high, you will have trouble
controlling the kiln if it fires uneven. This is because, depending on the
kiln mfg., medium could put the elements in series for that kiln ring which
would allow the ring to be at 50 % power. If you have infinite type switches
than you can set them at any rate you want to compensate for uneven or too
fast firing. The very best way to control the kiln is with a two zone
controller like Ron Roy suggested. This would be a very expensive retrofit.
Another way to go is to change to infinite type switches and /or get a
digital controller. Your kiln mfg. could help or try the 1-800-304-6185
number these people were at NECCA and could certainly help.
David
Cheryl L Litman on sat 7 jun 97
Snip from Ron Roy
>Fast firings are uneven usually - slower firings - particularly at the
end
>are more even. A rise of 50C per hour or less for the last 200C will
help
>even out firings, improve glaze quality and allow a better glaze/clay
bond
>to develop.
Question?
How does one control the temperature rise in a Skutt for example with
nothing more than low, medium, high switches? Do we have to get a
pyrometer to know the temperature, can you intuit it from witness cones?
To control I guess I'm back to turning one or more of the switches from
high to medium to slow it down?
Ron Roy on sun 8 jun 97
Question?
>How does one control the temperature rise in a Skutt for example with
>nothing more than low, medium, high switches? Do we have to get a
>pyrometer to know the temperature, can you intuit it from witness cones?
>To control I guess I'm back to turning one or more of the switches from
>high to medium to slow it down?
As the previous post pointed out - different switching systems work in
different ways and I don't know about that part. I do recommend a pyrometer
to establish soaking periods - low fire ones will help but it will be very
difficult - once the cones have melted (expect a puddle) it is useless.
I should add as well : The Orton controller is about $900 in Canada - that
should be US $650. Quite a price breakthrough for this type of controller -
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/ronroy.htm
Fay & Ralph Loewenthal on mon 9 jun 97
I was horrified to see the price of controllers in the USA,
as against what I pay here in the backwoods of ceramic
Hillbilly country in South Africa. When refurbishing kilns I
usually go to a supplier who has refurbished controllers.
I pay SA R400.00, less than US$100.00 for one that new
goes for 4 times the price. I can get a programmable
controller with 8 programs and 10 steps in each for
US$400.00. It could be our kilns are of such an old
design that we can make do with simpler controllers. It
always struck me that the equipment that one could buy
in the States was so much more sophisticated than what
we can get here.
After all that I soak on the way up at 573C for half an
hour and at the top for at least another half an hour.
Soaking means to set your temperature control at the
required temperature and letting it stay there for the
time required. Here I have to do it manually as I do not
have one these fancy programable controllers. I asked
one the potters who uses only cones, no controller, and
she said she sets her energy regulator, basicly a stove's
oven switch, to 5.5 which is just below the top setting, 6.
This switch switches in and out and tends to hold the
temperature correctly.
I hope this helps, if you want any wiring diagrams or any
further info email me direct at fayralph@sprintlink.co.za
Ralph in PE SA
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