Nancy Braches on tue 17 oct 06
Fred
I don't know the "right" answer but the cooling part of my kiln, once the cone sitter shuts it off, I leave it until the next day and then open it. Seems to work.
Nancy
Fred Parker wrote: My Skutt 1027 has three high/med/low switches, a kilnsitter and no timer.
I have no pyrometer. Does anyone with a similar kiln have a recommended
slow cool procedure? Couldn't find anything specific in the archives,
although there's much discussion on the topic there.
In my last glaze firing (various glazes) I did a "SWAG" and came up with
the following, which rendered some good, some ok -- and some pretty
crappy -- results:
At ^6 reset drop switch and set all 3 switched to med.
After 30 minutes, set all switches to low.
After 12 minutes, set all switches to med.
After 14 minutes, set all switches to low.
After 15 minutes, set all switches to med.
After 15 minutes all switches off.
Looking back over it, I now realize this wasn't enough total time, even if
the cooling rate was what I needed (which I don't know). Without a
pyrometer, I'm afraid I'll cool too fast if I just go to medium and leave
it there? Is it ever ok to set (for example) two switches to medium and
the other to high? Many thanks for any suggestions.
Fred Parker
who finished six more fairly decent terra cotta mugs yesterday...
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Nancy
Hilltop Pottery
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Fred Parker on tue 17 oct 06
My Skutt 1027 has three high/med/low switches, a kilnsitter and no timer.
I have no pyrometer. Does anyone with a similar kiln have a recommended
slow cool procedure? Couldn't find anything specific in the archives,
although there's much discussion on the topic there.
In my last glaze firing (various glazes) I did a "SWAG" and came up with
the following, which rendered some good, some ok -- and some pretty
crappy -- results:
At ^6 reset drop switch and set all 3 switched to med.
After 30 minutes, set all switches to low.
After 12 minutes, set all switches to med.
After 14 minutes, set all switches to low.
After 15 minutes, set all switches to med.
After 15 minutes all switches off.
Looking back over it, I now realize this wasn't enough total time, even if
the cooling rate was what I needed (which I don't know). Without a
pyrometer, I'm afraid I'll cool too fast if I just go to medium and leave
it there? Is it ever ok to set (for example) two switches to medium and
the other to high? Many thanks for any suggestions.
Fred Parker
who finished six more fairly decent terra cotta mugs yesterday...
Cindy Gatto on tue 17 oct 06
Usually you just go to med then to low then to off I don't understand why
you are going up and down?If you want to slow cool when the kiln shuts off just
reset it to med for x amount of time then go to low for x amount of time then
off other things you could do is shut down the vent or vary the switches for
example the kiln goes off you turn one switch to med 2 left on high for 15
min then 1 more to med for 15 min then the third switch to med for 15 min then
1 to low for 15 min then a second to low 15 min then third to low 15 min
then 1 to off etc, etc or any combination but with the temp going down not down
then up Also keep in mind some glazes look better with a fast cooling You
need to learn your glazes and what cycle you like It isn't as simple as slow
cool everything We have several glazes that look like crap with a slow cool
but are beautiful with a fast cool and I have learned this by experimenting and
firing accordingly. There is no one way to do anything in clay it is what
works for you
Cindy Gatto & Mark Petrin
The Mudpit
228 Manhattan Ave
Brooklyn, NY 11206
718-218-9424
_www.mudpitnyc.com_ (http://www.mudpitnyc.com/)
mudpitnyc@aol.com
Snail Scott on tue 17 oct 06
On Oct 17, 2006, at 11:22 AM, Fred Parker wrote:
> My Skutt 1027 has three high/med/low switches, a kilnsitter and no
> timer.
> I have no pyrometer. Does anyone with a similar kiln have a
> recommended
> slow cool procedure?
>
> In my last glaze firing (various glazes) I did a "SWAG" and came up
> with
> the following, which rendered some good, some ok -- and some pretty
> crappy -- results:
>
> At ^6 reset drop switch and set all 3 switched to med.
> After 30 minutes, set all switches to low.
> After 12 minutes, set all switches to med.
> After 14 minutes, set all switches to low.
> After 15 minutes, set all switches to med.
> After 15 minutes all switches off.
>
> Looking back over it, I now realize this wasn't enough total time,
> even if
> the cooling rate was what I needed (which I don't know). Without a
> pyrometer, I'm afraid I'll cool too fast if I just go to medium and
> leave
> it there? Is it ever ok to set (for example) two switches to medium
> and
> the other to high?
First: setting some switches to one setting
and the others to another is a really useful
way to even out an uneven load, and to
fine-tune your firing results. If you've been
denying yourself this handy option, cut it
out! It's totally OK to do.
Second: I don't have a pyrometer either. I
slow-cool my electric kiln by keeping a
higher cone in the sitter, and using witness
cones to tell me when to stop. That way I
don't have to fuss with re-setting anything,
since it never turns itself off, and I get to
pick the exact turn-off point more precisely
than a sitter cone.
When I hit temperature, I don't do anything
as fancy as your schedule. I just turn all the
knobs to medium, and set the timer for three
hours. At that point, I turn the thing off and let
it cool naturally. I don't know what the exact
temperature range is when I do this, but I
do like the results with my matte glazes.
I know from experience that 'all on medium'
allows the temperature to eventually drop
below the point where it has much effect on
mid-range glazes, but it spends enough time
in the 'zone' to be useful. I doubt that a
significantly longer time on 'all medium'
would add improve results much.
For a _very_ long cool/soak, a combo of
medium and high would be needed. I use
high for the top and bottom, and medium
for the middle - this will hold the temperature
somewhere at the high end of the earthenware
range indefinitely, depending on the condition
of your elements. A little cooler may be best,
but you'd have to tweak the settings a bit -
some time on medium, then back to high for
a bit, etc.
Remember, slow cooling is great for matte
glazes, as it gives time for microcrystalline
development, which is what makes 'true' matte
glazes matte. If your 'matte' glazes are actually
just undervitrified, the extra soak might make
them more glossy instead. And if your glazes
are supposed to be glossy, well, some may
stay that way in spite of a long cool-down,
and some may not. It all depends on the
formulation, and your intentions. Slow cooling
ain't for everything.
-Snail
Craig Clark on tue 17 oct 06
Fred, I have a 1027 and have been firing down since I got religion
and learned about the wonderful results that one gets when firing down a
kiln. This all came about a few years back after first hearing about and
then reading Ron and Johns book.
What has worked for me is to hold the kiln at peak temp, (firing to
cone 6?) for about 30 minutes and then start the firing down. Initially
I played around a bit looking for a formula of some type but pretty much
figured out that the method to be used depends upon the load of pots in
the kiln. The more pots, the heavier the heat mass, the slower the temp
will drop seems to be a rule of thumb.
After the initial peak soak I let the temp free fall, by turning all
the controls to low, until the temperature gauge from the pyrometer
indicates 2000 F. At that point I start to slow the drop by first
turning the top element to high, and then the middle control if
necessary. I just go for a combo of high and medium that let's the kiln
temp continue to drop, but at a speed of no faster than 75 degrees F per
hour. Ideally, I'm after about 50 Degress F per hour from 1950 F, or so,
on down to a bit under 1600 degrees F. This speed of decent gives me the
results which I am after. Speeding up or slowing down will yield
appreciable differences with some glazes.
If the kiln temp doesn't seem to be dropping enough once you get
down below 1900 F with two controls on high and one on medium, try going
for a two one medium and one on high. Next just click down to all on
medium. If I have a good heavy load, all the controls set to medium
seems to do the trick. I have also made sure that I keep the upper most
control on a higher setting than the middle. If I need two controls set
to high, and one to medium, it will be the top and bottom elements on
High and the middle on Medium. I do this since the kiln seems to loose
heat more quickly out of the bottom and top. I also place the pyrometer
as close to the center of the kiln as possible, without the tip being in
the immediate proximity of either a shelf, shelf support, or a pot that
is too close.
Hope this helps
Craig Dunn Clark
619 East 11 1/2 St
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
Fred Parker wrote:
> My Skutt 1027 has three high/med/low switches, a kilnsitter and no timer.
> I have no pyrometer. Does anyone with a similar kiln have a recommended
> slow cool procedure? Couldn't find anything specific in the archives,
> although there's much discussion on the topic there.
>
> In my last glaze firing (various glazes) I did a "SWAG" and came up with
> the following, which rendered some good, some ok -- and some pretty
> crappy -- results:
>
> At ^6 reset drop switch and set all 3 switched to med.
> After 30 minutes, set all switches to low.
> After 12 minutes, set all switches to med.
> After 14 minutes, set all switches to low.
> After 15 minutes, set all switches to med.
> After 15 minutes all switches off.
>
> Looking back over it, I now realize this wasn't enough total time, even if
> the cooling rate was what I needed (which I don't know). Without a
> pyrometer, I'm afraid I'll cool too fast if I just go to medium and leave
> it there? Is it ever ok to set (for example) two switches to medium and
> the other to high? Many thanks for any suggestions.
>
> Fred Parker
> who finished six more fairly decent terra cotta mugs yesterday...
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
>
Ron Roy on sun 22 oct 06
Hi Fred,
You are going to need a pyrometer - they are not expensive - but until you
have one you will not be able to estimate temperature drop.
Knowing which parts of your kiln tend to be cooler will also help so put
cones on every level to find out.
Keep in mind - the slow cooling that does the most good is between 1000C
and 800C so turning all the switches off till the kiln drops to 1000C is
the better way to do it (after a soak period to even out the firing.)
Then you can fiddle with the switches - and remember - all on medium is not
the only option - one on high and two on medium might be useful for
instance.
A soak or very slow cool for a few minutes at the end of a firing is very
beneficial - just make sure you have stopped the cones at the right level
so you don't overfire during the soak.
RR
>My Skutt 1027 has three high/med/low switches, a kilnsitter and no timer.
>I have no pyrometer. Does anyone with a similar kiln have a recommended
>slow cool procedure? Couldn't find anything specific in the archives,
>although there's much discussion on the topic there.
>
>In my last glaze firing (various glazes) I did a "SWAG" and came up with
>the following, which rendered some good, some ok -- and some pretty
>crappy -- results:
>
>At ^6 reset drop switch and set all 3 switched to med.
>After 30 minutes, set all switches to low.
>After 12 minutes, set all switches to med.
>After 14 minutes, set all switches to low.
>After 15 minutes, set all switches to med.
>After 15 minutes all switches off.
>
>Looking back over it, I now realize this wasn't enough total time, even if
>the cooling rate was what I needed (which I don't know). Without a
>pyrometer, I'm afraid I'll cool too fast if I just go to medium and leave
>it there? Is it ever ok to set (for example) two switches to medium and
>the other to high? Many thanks for any suggestions.
>
>Fred Parker
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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