jcullen on thu 28 sep 00
I like to candle for 1 - 2 hours (depending on when I glazed). The I start
on 2 for 1 hour. Bump it to 4 for 1 hours Bump it to 6 for 1 hour. Then on
HI til it shuts down. Then I soak for 1 hour and shut it off. I won't open
until it's room temp.
That's my plan and I'm stickin' to it.
KEEP CENTERED
Cullen
Naperville, Illinois
----- Original Message -----
From: "Millie Carpenter"
To:
Sent: Thursday, September 28, 2000 7:02 AM
Subject: slower electric firing?
> I have a question about ^6 electric firing. I was taught to fire by
leaving it on
> two bottom switches on low all night, close the lid and turn all switches
on low,
> after a half hour shut the peeps and put it on med, after an hour on med,
put it on
> high and let it rip. when it shuts, off it shuts off. open as soon as it
is cool
> enough.
>
> I have modified this to leaving it on low for an hour and a half, and two
hours on
> medium, then high till it shuts off, when the cone sitter shuts it off, I
turn it
> back on high on the bottom two, med on the top for about an hour and then
low on
> the bottom two for another hour, then shut it off and let it cool, this
give me a
> flat ^5 and a Bending ^6. People talk about ramping and holding and
firing
> slowly, well I don't have a pyrometer or an auto controller, yet, and I
am not
> sure what to try to get more depth to my glazes. I do layer them. but...
>
> this kiln has variable speeds, not just hi, med, & low, but I am not
clear on how
> I figure out how to use the numbers and time in combination to bring it up
one or
> two hundred degrees an hour. Some suggestions please
>
> Millie in MD, where the sun is shining!!!
>
>
> > I would suggest you try to slow down your firing rather
> > than 'fire down' on cooling.
> >
> > Some glazes, especially those that can develop micro crystals,
> > benefit from a slow cooling. This give the crystals time
> > to develop, and is why slower cooling brick kilns can be
> > better for this.
> > Often, people think reduction fired pots look better than
> > oxidation fired pots, but what they are really seeing
> > is the slow cooled glaze from a typical gas kiln compared
> > to the rapid cooled glaze from an electric kiln
>
>
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Millie Carpenter on thu 28 sep 00
I have a question about ^6 electric firing. I was taught to fire by leaving it on
two bottom switches on low all night, close the lid and turn all switches on low,
after a half hour shut the peeps and put it on med, after an hour on med, put it on
high and let it rip. when it shuts, off it shuts off. open as soon as it is cool
enough.
I have modified this to leaving it on low for an hour and a half, and two hours on
medium, then high till it shuts off, when the cone sitter shuts it off, I turn it
back on high on the bottom two, med on the top for about an hour and then low on
the bottom two for another hour, then shut it off and let it cool, this give me a
flat ^5 and a Bending ^6. People talk about ramping and holding and firing
slowly, well I don't have a pyrometer or an auto controller, yet, and I am not
sure what to try to get more depth to my glazes. I do layer them. but...
this kiln has variable speeds, not just hi, med, & low, but I am not clear on how
I figure out how to use the numbers and time in combination to bring it up one or
two hundred degrees an hour. Some suggestions please
Millie in MD, where the sun is shining!!!
> I would suggest you try to slow down your firing rather
> than 'fire down' on cooling.
>
> Some glazes, especially those that can develop micro crystals,
> benefit from a slow cooling. This give the crystals time
> to develop, and is why slower cooling brick kilns can be
> better for this.
> Often, people think reduction fired pots look better than
> oxidation fired pots, but what they are really seeing
> is the slow cooled glaze from a typical gas kiln compared
> to the rapid cooled glaze from an electric kiln
Cindy Strnad on thu 28 sep 00
Hello, Millie.
See if your kiln can make ^6 on medium. My small one can, and it does help
to slow down the firing. These smaller kilns are capable of very quick
firings, but it doesn't always do the glaze justice. Also, it may simply be
that you don't like your glazes and need to try something else.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
www.earthenvesselssd.com
John Baymore on fri 29 sep 00
People talk about ramping and holding and firing
slowly, well I don't have a pyrometer or an auto controller, yet, and I =
am
not
sure what to try to get more depth to my glazes. I do layer them. but..=
..
this kiln has variable speeds, not just hi, med, & low, but I am not
clear on how
I figure out how to use the numbers and time in combination to bring it u=
p
one or
two hundred degrees an hour. Some suggestions please
Millie.
You'll probably hate me fo this suggestion ...... but I think you ough=
t
to invest AT LEAST in a pyrometer. It will give you more information tha=
n
is currently available to you through your human senses..... and will spe=
ed
the learning curve. =
Rate of climb of a kiln depends on many things.....one of the more
significant is the mass of the load in it and the ability of the partular=
load to (for lack of a better term) "absorb" heat. So each load can alte=
r
the firing rate a bit even if the controls are set the same. The same
"switch settings" for one firing load density can be a bit different rate=
of climb from another load stacked at differnt density. This makes for a=
"pain in the butt" if you assume that one switch setting always results t=
he
same rate of climb. (No different relative to heat input on a gas or woo=
d
kiln.)
So....with a pyrometer you can get a general feel for the rate of climb a=
t
any particular switch setting......... but it will be a "guideline" only.=
=
Also as the temperature rises and heat loses through the refractory linin=
g
change due to increasing hot face/cold face differential ...... the rate =
of
climb at a particular given switch setting will change a bit depending on=
the temperature inside the kiln.
"Cookbook" type firing works OK when the loads are about identical firing=
to firing (common industrial firings are set to specific "programs"......=
...
because the loads are about identical firing to firing)..... but to gain=
real control of kilns it helps to really understand how they work and wha=
t
the clay and glaze materials are doing at any given point in time. To us=
e
this knowledge it also helps to have some information available....like
current temperature and current rate of climb.
Hard to tell out without knowing .
A pyrometer will help you see how fast the kiln is climbing within the
level of accuracy of the particular unit you purchase. You can get a
pretty good digital one these days for $200 bucks or so. Compared to usi=
ng
nothing, even the "cheapie" $90 analog ones will give you some general
information that will head you in the right direction. A few screwed up
pots saved will pay for the pyrometer if you sell your wares.....and the
cost of the pyrometer is just part of your "tuition payments" for "Millie=
's
School of Ceramics" if you are more of a student or hobbiest type potter.=
BTW....... One of the reasons that the computerized electronic controller=
s
are so prevalent these days is that if you want to gain fine control over=
electric firing..... you can spend your life running back and forth turni=
ng
element switches up and down . The controller allows you to "get a
life" outside timing of switch changes .
So...... easy for ME to spend YOUR money, huh ?
Best,
..............................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JBaymore@compuserve.com
John.Baymore@GSD-CO.com
"Earth, Water, and Fire Noborigama Woodfiring Workshop August 18-27,
2000"
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