asim mahmood on mon 6 nov 06
I have been working on cone 6 glazes in a skutt kiln fitted with
Kiln Sitter without putting any witness cone. The results have never been up
to my entire satisfaction. This time instead of having cone 6 in the sitter
I put cone 7 with witness cones 5 and 6 just across the spy hole with a view
to ensure proper monitoring and soaking.
At the terminal stage of the firing once cone 5 was properly bent (
not touching the shelf and cone 6 was its down ward journey to 10 O’clock
position ) and I was just thinking about soaking and shutting the kiln
manually the sitter tripped off automatically, shutting the kiln. I spent
the day in agony and waited for the kiln to cool down. Next day once I un
loaded the kiln I found the results were better than before except my folk
pottery having brown stain appeared to be a bit over fired. Now I have a few
questions in this back drop:-
a. Since the sitter tripped off at cone 7 when the witness cone 6 was still
its down ward journey clearly suggests that the temperature in the kiln was
not uniform and it had not reached to cone 6. So what is the best way to
achieve a uniform ^ 6 temp inside and at the sitter? Is there some thing
wrong with the sitter? Or does it needs calibration? If so how and from
where.
b. How to achieve soaking after attaining ^ 6 temp as cone in the sitter
(^6) would not allow you to do that.
c. How to achieve gradual cooling down with manual control system.
I need your guidance and thanks in advance.
Asim
Mahmood.
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Arnold Howard on mon 6 nov 06
From: "asim mahmood"
So what is the best way to
achieve a uniform ^ 6 temp inside and at the sitter? Is
there some thing
wrong with the sitter? Or does it needs calibration? If so
how and from
where.
b. How to achieve soaking after attaining ^ 6 temp as
cone in the sitter
(^6) would not allow you to do that.
c. How to achieve gradual cooling down with manual
control system.
----------------
It is normal for the Kiln Sitter to require a hotter cone
than the witness cone. I wouldn't worry about that.
You will need a firing gauge to calibrate the Kiln Sitter.
It is a disk that slides onto the two cone supports. The
actuating rod goes through a center hole in the firing
gauge. With the gauge in place, adjust the trigger (on the
outside of the Kiln Sitter) so that it barely touches the
release claw. This is much easier to do than to describe.
You might find the disk in the instruction packet that came
with the kiln.
To soak after the Kiln Sitter shuts off, raise the weight,
press in the plunger, and gently lower the weight. Turn the
switches to a medium setting. You will need to shut off the
kiln manually since this procedure by-passes the Kiln
Sitter. To do a slow cooling, lower the switch setting.
To hold and soak accurately, you will need a pyrometer.
Otherwise you can estimate the temperature by noting the
color of the kiln interior.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
asim mahmood on mon 6 nov 06
Arnold,
Thanks a lot for explaining me so well and in simple terms,
clearing all the haze and leaving no doubt in my mind. I must acknowledge
and appreciate the prompt response and concern being shown by members to one
and other. Having no fromal training in ceramics, I feel proud and lucky to
be on this forum and getting advice from professionals with just Klick of a
Key. Thank you once again.
Asim.
>From: Arnold Howard
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: Glaze Firing ^ 6
>Date: Mon, 6 Nov 2006 14:03:27 -0600
>
>From: "asim mahmood"
>So what is the best way to
>achieve a uniform ^ 6 temp inside and at the sitter? Is
>there some thing
>wrong with the sitter? Or does it needs calibration? If so
>how and from
>where.
>b. How to achieve soaking after attaining ^ 6 temp as
>cone in the sitter
>(^6) would not allow you to do that.
>c. How to achieve gradual cooling down with manual
>control system.
>----------------
>
>It is normal for the Kiln Sitter to require a hotter cone
>than the witness cone. I wouldn't worry about that.
>
>You will need a firing gauge to calibrate the Kiln Sitter.
>It is a disk that slides onto the two cone supports. The
>actuating rod goes through a center hole in the firing
>gauge. With the gauge in place, adjust the trigger (on the
>outside of the Kiln Sitter) so that it barely touches the
>release claw. This is much easier to do than to describe.
>You might find the disk in the instruction packet that came
>with the kiln.
>
>To soak after the Kiln Sitter shuts off, raise the weight,
>press in the plunger, and gently lower the weight. Turn the
>switches to a medium setting. You will need to shut off the
>kiln manually since this procedure by-passes the Kiln
>Sitter. To do a slow cooling, lower the switch setting.
>
>To hold and soak accurately, you will need a pyrometer.
>Otherwise you can estimate the temperature by noting the
>color of the kiln interior.
>
>Sincerely,
>
>Arnold Howard
>Paragon Industries, L.P., Mesquite, Texas USA
>ahoward@paragonweb.com / www.paragonweb.com
>
>______________________________________________________________________________
>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.
_________________________________________________________________
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John Hesselberth on mon 6 nov 06
Hi Asim,
I'll give your questions a try. See below.
On Nov 6, 2006, at 1:20 PM, asim mahmood wrote:
> a. Since the sitter tripped off at cone 7 when the witness
> cone 6 was still
> its down ward journey clearly suggests that the temperature in the
> kiln was
> not uniform and it had not reached to cone 6. So what is the best
> way to
> achieve a uniform ^ 6 temp inside and at the sitter? Is there some
> thing
> wrong with the sitter? Or does it needs calibration? If so how and
> from
> where.
I never let a kiln turn off with a sitter. They are usually off by at
least a cone and doing that doesn't allow for a good soak unless you
overide the sitter--something I do not recommend. I put a cone 9 in
my sitter and just use it as a safety backup (which is what it is
intended to be anyhow). Then I use and watch witness cones. When cone
6 is about 10 o'clock I would turn the kiln down to medium in the hot
spots and leave it on high in the cool section. Hold it that way (or
fiddle with it you your cones are not beginning to even out) for
20-30 minutes or until cone 6 is down where you want it. Then turn
the kiln off for about half an hour--if you have a thermocouple turn
it off until you are down to 1900F
> b. How to achieve soaking after attaining ^ 6 temp as cone in
> the sitter
> (^6) would not allow you to do that.
See above. Don't let the sitter turn the kiln off.
> c. How to achieve gradual cooling down with manual control
> system.
When you are down to 1900 turn the kiln back on to medium. Leave it
there for a couple hours then turn it to low for a couple more hours.
Adjust to taste.
Regards,
John
asim mahmood on mon 6 nov 06
John,
Thanks, you have further crystalized answers to my questions.
Regards,
Asim Mahmood
>From: John Hesselberth
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: Glaze Firing ^ 6
>Date: Mon, 6 Nov 2006 18:59:19 -0500
>
>Hi Asim,
>
>I'll give your questions a try. See below.
>On Nov 6, 2006, at 1:20 PM, asim mahmood wrote:
>
>>a. Since the sitter tripped off at cone 7 when the witness
>>cone 6 was still
>>its down ward journey clearly suggests that the temperature in the
>>kiln was
>>not uniform and it had not reached to cone 6. So what is the best
>>way to
>>achieve a uniform ^ 6 temp inside and at the sitter? Is there some
>>thing
>>wrong with the sitter? Or does it needs calibration? If so how and
>>from
>>where.
>
>I never let a kiln turn off with a sitter. They are usually off by at
>least a cone and doing that doesn't allow for a good soak unless you
>overide the sitter--something I do not recommend. I put a cone 9 in
>my sitter and just use it as a safety backup (which is what it is
>intended to be anyhow). Then I use and watch witness cones. When cone
>6 is about 10 o'clock I would turn the kiln down to medium in the hot
>spots and leave it on high in the cool section. Hold it that way (or
>fiddle with it you your cones are not beginning to even out) for
>20-30 minutes or until cone 6 is down where you want it. Then turn
>the kiln off for about half an hour--if you have a thermocouple turn
>it off until you are down to 1900F
>>b. How to achieve soaking after attaining ^ 6 temp as cone in
>>the sitter
>>(^6) would not allow you to do that.
>
>See above. Don't let the sitter turn the kiln off.
>>c. How to achieve gradual cooling down with manual control
>>system.
>
>When you are down to 1900 turn the kiln back on to medium. Leave it
>there for a couple hours then turn it to low for a couple more hours.
>Adjust to taste.
>
>Regards,
>
>John
>
>______________________________________________________________________________
>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.
_________________________________________________________________
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Snail Scott on tue 7 nov 06
At 01:20 PM 11/6/2006 -0500, you wrote:
> ...I have been working on cone 6 glazes in a skutt kiln fitted with
>Kiln Sitter without putting any witness cone. The results have never been=
up
>to my entire satisfaction. This time instead of having cone 6 in the sitter
>I put cone 7 with witness cones 5 and 6 just across the spy hole with a=
view
>to ensure proper monitoring and soaking... Since the sitter tripped off at
cone 7 when the witness cone 6 was still
>its down ward journey clearly suggests that the temperature in the kiln was
>not uniform and it had not reached to cone 6.
This is totally normal in my experience, and is=20
usual for others as well. I always put a higher=20
cone in the sitter to correspond to a lower=20
witness cone. This does't bother me any. Who=20
cares if the cone in the sitter has '7' stamped=20
on it, if it gives you the results you want?=20
This doesn't imply 'unevenness', just a common,=20
almost normal, discrepancy between sitter cones=20
and witness cones in that particular application.=20
If you are really bothered by it, you can=20
recalibrate your sitter.
The nominal correct bend for a sitter cone=20
is 90=BA. If it's not, that should be corrected.
For the 90=BA bend, there is a template you can=20
get from most suppliers, but it isn't really=20
necessary; the adjustment can be done by eye=20
and readjusted based on the results of firing.
If it is 90=BA, then you can adjust the sitter=20
to shut off at a greater or lesser degree of=20
bending. Since yours shuts off at 'almost ^6'=20
when a^7 is in the sitter, you want it to not=20
shut off 'til a greater bend is reached, so=20
that a ^6 will shut it off, but only after=20
true ^6 heat-work has been reached.
To do the actual adjustment, look on the outside=20
of the sitter. On the deadfall flap (the bit=20
that you lift up and set to start the firing,=20
and which flops down at the end) you will see a
tiny set screw. This can be turned with a small=20
screwdriver (like for eyeglasses) or a knife tip.=20
Above that (below, when in the 'off' position)=20
is a piece of flat metal sticking out of the=20
main flap. This is what the set screw holds in=20
place. Sliding that tab of flat metal further=20
into the flap will make the sitter shut off=20
at a flatter bend in the cone (cooler). Sliding=20
that metal tab further out will make the sitter=20
shut off at a greater angle in the cone (hotter).=20
Very small sdjustments make big differences.
You can fine-tune your firings to a high=20
precision, a little hotter or cooler than the=20
nominal cone, or dead on. Not every glaze fires=20
best at exactly some nominal cone number,=20
though, and why should it? Just because we=20
don't have an efficient way of saying, say,=20
^5-3/4, doesn't mean it might not be perfect=20
for what some particular glaze requires.
(Before adjusting the sliding tab, tape it=20
into place! Otherwise, when you loosen the=20
set screw, the tab will just slide freely and=20
you'll lose track of where it started out.)=20
So, you can do this and recalibrate your sitter,=20
or not. Personally, I wouldn't bother. You have=20
more flexibility and accuracy by using witness=20
cones to judge when to shut down, and you can=20
fire a little bit hotter or cooler as the notion=20
takes you without recalibrating the equipment.
When I fire to ^6, I put a ^8 in the sitter,=20
and use it solely as a fail-safe, to shut it=20
down if I get called away or incapacitated,=20
not as the absolute determiner of the correct=20
heat-work. =20
Not everyone can be there for the end of a=20
firing, such as teachers who have to fire=20
after school, but if you are in your own=20
studio, why not? Why abdicate such an=20
important step to a gadget, even one as=20
simple and reliable as a kiln sitter? Witness=20
cones are cheap insurance against bad firings.=20
I don't mind using the sitter to shut down a=20
bisque fire, where I don't really care about=20
precision, but I'd rather make the call=20
myself on a glaze firing.=20
Safer, too. A watched kiln never overfires;=20
mechanical failure is irrelevant if you are=20
there to pull the plug.
-Snail
Randy MCCALL on tue 7 nov 06
I have found that in my Skutt 1027 that if you put a Cone 6 in the sitter
and it falls, cut the kiln back on high and leave for 20 minutes you will
get a good Cone 6.
Just for information.
Randy
South Carolina
Pottery Web site
http://members.tripod.com/~McCallJ/index.html
>From: Snail Scott
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: Glaze Firing ^ 6
>Date: Tue, 7 Nov 2006 09:40:55 -0600
>
>At 01:20 PM 11/6/2006 -0500, you wrote:
> > ...I have been working on cone 6 glazes in a skutt kiln fitted with
> >Kiln Sitter without putting any witness cone. The results have never been
>up
> >to my entire satisfaction. This time instead of having cone 6 in the
>sitter
> >I put cone 7 with witness cones 5 and 6 just across the spy hole with a
>view
> >to ensure proper monitoring and soaking... Since the sitter tripped off
>at
>cone 7 when the witness cone 6 was still
> >its down ward journey clearly suggests that the temperature in the kiln
>was
> >not uniform and it had not reached to cone 6.
>
>
>
>This is totally normal in my experience, and is
>usual for others as well. I always put a higher
>cone in the sitter to correspond to a lower
>witness cone. This does't bother me any. Who
>cares if the cone in the sitter has '7' stamped
>on it, if it gives you the results you want?
>
>This doesn't imply 'unevenness', just a common,
>almost normal, discrepancy between sitter cones
>and witness cones in that particular application.
>If you are really bothered by it, you can
>recalibrate your sitter.
>
>The nominal correct bend for a sitter cone
>is 90º. If it's not, that should be corrected.
>For the 90º bend, there is a template you can
>get from most suppliers, but it isn't really
>necessary; the adjustment can be done by eye
>and readjusted based on the results of firing.
>If it is 90º, then you can adjust the sitter
>to shut off at a greater or lesser degree of
>bending. Since yours shuts off at 'almost ^6'
>when a^7 is in the sitter, you want it to not
>shut off 'til a greater bend is reached, so
>that a ^6 will shut it off, but only after
>true ^6 heat-work has been reached.
>
>To do the actual adjustment, look on the outside
>of the sitter. On the deadfall flap (the bit
>that you lift up and set to start the firing,
>and which flops down at the end) you will see a
>tiny set screw. This can be turned with a small
>screwdriver (like for eyeglasses) or a knife tip.
>Above that (below, when in the 'off' position)
>is a piece of flat metal sticking out of the
>main flap. This is what the set screw holds in
>place. Sliding that tab of flat metal further
>into the flap will make the sitter shut off
>at a flatter bend in the cone (cooler). Sliding
>that metal tab further out will make the sitter
>shut off at a greater angle in the cone (hotter).
>
>Very small sdjustments make big differences.
>You can fine-tune your firings to a high
>precision, a little hotter or cooler than the
>nominal cone, or dead on. Not every glaze fires
>best at exactly some nominal cone number,
>though, and why should it? Just because we
>don't have an efficient way of saying, say,
>^5-3/4, doesn't mean it might not be perfect
>for what some particular glaze requires.
>
>(Before adjusting the sliding tab, tape it
>into place! Otherwise, when you loosen the
>set screw, the tab will just slide freely and
>you'll lose track of where it started out.)
>
>So, you can do this and recalibrate your sitter,
>or not. Personally, I wouldn't bother. You have
>more flexibility and accuracy by using witness
>cones to judge when to shut down, and you can
>fire a little bit hotter or cooler as the notion
>takes you without recalibrating the equipment.
>When I fire to ^6, I put a ^8 in the sitter,
>and use it solely as a fail-safe, to shut it
>down if I get called away or incapacitated,
>not as the absolute determiner of the correct
>heat-work.
>
>Not everyone can be there for the end of a
>firing, such as teachers who have to fire
>after school, but if you are in your own
>studio, why not? Why abdicate such an
>important step to a gadget, even one as
>simple and reliable as a kiln sitter? Witness
>cones are cheap insurance against bad firings.
>I don't mind using the sitter to shut down a
>bisque fire, where I don't really care about
>precision, but I'd rather make the call
>myself on a glaze firing.
>
>Safer, too. A watched kiln never overfires;
>mechanical failure is irrelevant if you are
>there to pull the plug.
>
>
> -Snail
>
>______________________________________________________________________________
>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 tue 7 nov 06
Hi Asim,
Just to add a little - soaking is a very good way to even out a firing -
and slowing down before the end is almost as good.
I second the advice to get a pyrometer - don't trust it to tell you the
actual temperature - use it to tell if you are increasing, holding or
losing temperature.
The best thing would be to find out which combination of switch setting
would hold temperature the best - keeping in mind - where the kiln is
coolest - to have the switch for that section on high.
Put cones at every level in your kiln to see where the hot and cold spots
are - once you know that you won't need as many - I only use one cone now
but I have a two zone controller - that and an element in the floor is the
best system I have ever used.
RR
>From: "asim mahmood"
>So what is the best way to
>achieve a uniform ^ 6 temp inside and at the sitter? Is
>there some thing
>wrong with the sitter? Or does it needs calibration? If so
>how and from
>where.
>b. How to achieve soaking after attaining ^ 6 temp as
>cone in the sitter
>(^6) would not allow you to do that.
>c. How to achieve gradual cooling down with manual
>control system.
>----------------
>
>It is normal for the Kiln Sitter to require a hotter cone
>than the witness cone. I wouldn't worry about that.
>
>You will need a firing gauge to calibrate the Kiln Sitter.
>It is a disk that slides onto the two cone supports. The
>actuating rod goes through a center hole in the firing
>gauge. With the gauge in place, adjust the trigger (on the
>outside of the Kiln Sitter) so that it barely touches the
>release claw. This is much easier to do than to describe.
>You might find the disk in the instruction packet that came
>with the kiln.
>
>To soak after the Kiln Sitter shuts off, raise the weight,
>press in the plunger, and gently lower the weight. Turn the
>switches to a medium setting. You will need to shut off the
>kiln manually since this procedure by-passes the Kiln
>Sitter. To do a slow cooling, lower the switch setting.
>
>To hold and soak accurately, you will need a pyrometer.
>Otherwise you can estimate the temperature by noting the
>color of the kiln interior.
>
>Sincerely,
>
>Arnold Howard
>Paragon Industries, L.P., Mesquite, Texas USA
>ahoward@paragonweb.com / www.paragonweb.com
>
>______________________________________________________________________________
>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
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
asim mahmood on tue 7 nov 06
Snail,
Thanks a lot for taking time out and giving a very detailed
explanation. After getting Arnold, John and your response I am much wiser
and feeling more confident. Now just waiting to go back home to my studio,
fix the things and do the glaze firing.
In addition to putting your mail in to relavent folder, I have taken
its print out just to perserv it. I am very positive that this time results
would be better than before. Once again my fullest appreciations to you all
for putting me wise.
Asim Mahmood.
>From: Snail Scott
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: Glaze Firing ^ 6
>Date: Tue, 7 Nov 2006 09:40:55 -0600
>
>At 01:20 PM 11/6/2006 -0500, you wrote:
> > ...I have been working on cone 6 glazes in a skutt kiln fitted with
> >Kiln Sitter without putting any witness cone. The results have never been
>up
> >to my entire satisfaction. This time instead of having cone 6 in the
>sitter
> >I put cone 7 with witness cones 5 and 6 just across the spy hole with a
>view
> >to ensure proper monitoring and soaking... Since the sitter tripped off
>at
>cone 7 when the witness cone 6 was still
> >its down ward journey clearly suggests that the temperature in the kiln
>was
> >not uniform and it had not reached to cone 6.
>
>
>
>This is totally normal in my experience, and is
>usual for others as well. I always put a higher
>cone in the sitter to correspond to a lower
>witness cone. This does't bother me any. Who
>cares if the cone in the sitter has '7' stamped
>on it, if it gives you the results you want?
>
>This doesn't imply 'unevenness', just a common,
>almost normal, discrepancy between sitter cones
>and witness cones in that particular application.
>If you are really bothered by it, you can
>recalibrate your sitter.
>
>The nominal correct bend for a sitter cone
>is 90º. If it's not, that should be corrected.
>For the 90º bend, there is a template you can
>get from most suppliers, but it isn't really
>necessary; the adjustment can be done by eye
>and readjusted based on the results of firing.
>If it is 90º, then you can adjust the sitter
>to shut off at a greater or lesser degree of
>bending. Since yours shuts off at 'almost ^6'
>when a^7 is in the sitter, you want it to not
>shut off 'til a greater bend is reached, so
>that a ^6 will shut it off, but only after
>true ^6 heat-work has been reached.
>
>To do the actual adjustment, look on the outside
>of the sitter. On the deadfall flap (the bit
>that you lift up and set to start the firing,
>and which flops down at the end) you will see a
>tiny set screw. This can be turned with a small
>screwdriver (like for eyeglasses) or a knife tip.
>Above that (below, when in the 'off' position)
>is a piece of flat metal sticking out of the
>main flap. This is what the set screw holds in
>place. Sliding that tab of flat metal further
>into the flap will make the sitter shut off
>at a flatter bend in the cone (cooler). Sliding
>that metal tab further out will make the sitter
>shut off at a greater angle in the cone (hotter).
>
>Very small sdjustments make big differences.
>You can fine-tune your firings to a high
>precision, a little hotter or cooler than the
>nominal cone, or dead on. Not every glaze fires
>best at exactly some nominal cone number,
>though, and why should it? Just because we
>don't have an efficient way of saying, say,
>^5-3/4, doesn't mean it might not be perfect
>for what some particular glaze requires.
>
>(Before adjusting the sliding tab, tape it
>into place! Otherwise, when you loosen the
>set screw, the tab will just slide freely and
>you'll lose track of where it started out.)
>
>So, you can do this and recalibrate your sitter,
>or not. Personally, I wouldn't bother. You have
>more flexibility and accuracy by using witness
>cones to judge when to shut down, and you can
>fire a little bit hotter or cooler as the notion
>takes you without recalibrating the equipment.
>When I fire to ^6, I put a ^8 in the sitter,
>and use it solely as a fail-safe, to shut it
>down if I get called away or incapacitated,
>not as the absolute determiner of the correct
>heat-work.
>
>Not everyone can be there for the end of a
>firing, such as teachers who have to fire
>after school, but if you are in your own
>studio, why not? Why abdicate such an
>important step to a gadget, even one as
>simple and reliable as a kiln sitter? Witness
>cones are cheap insurance against bad firings.
>I don't mind using the sitter to shut down a
>bisque fire, where I don't really care about
>precision, but I'd rather make the call
>myself on a glaze firing.
>
>Safer, too. A watched kiln never overfires;
>mechanical failure is irrelevant if you are
>there to pull the plug.
>
>
> -Snail
>
>______________________________________________________________________________
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>
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>
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>melpots@pclink.com.
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asim mahmood on tue 7 nov 06
This is another way. Thanks.
Asim
>From: Randy MCCALL
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: Glaze Firing ^ 6
>Date: Tue, 7 Nov 2006 12:19:40 -0500
>
>I have found that in my Skutt 1027 that if you put a Cone 6 in the sitter
>and it falls, cut the kiln back on high and leave for 20 minutes you will
>get a good Cone 6.
>
>Just for information.
>
>
>
>Randy
>South Carolina
>Pottery Web site
>
>http://members.tripod.com/~McCallJ/index.html
>
>
>
>
>
>>From: Snail Scott
>>Reply-To: Clayart
>>To: CLAYART@LSV.CERAMICS.ORG
>>Subject: Re: Glaze Firing ^ 6
>>Date: Tue, 7 Nov 2006 09:40:55 -0600
>>
>>At 01:20 PM 11/6/2006 -0500, you wrote:
>> > ...I have been working on cone 6 glazes in a skutt kiln fitted with
>> >Kiln Sitter without putting any witness cone. The results have never
>>been
>>up
>> >to my entire satisfaction. This time instead of having cone 6 in the
>>sitter
>> >I put cone 7 with witness cones 5 and 6 just across the spy hole with a
>>view
>> >to ensure proper monitoring and soaking... Since the sitter tripped off
>>at
>>cone 7 when the witness cone 6 was still
>> >its down ward journey clearly suggests that the temperature in the kiln
>>was
>> >not uniform and it had not reached to cone 6.
>>
>>
>>
>>This is totally normal in my experience, and is
>>usual for others as well. I always put a higher
>>cone in the sitter to correspond to a lower
>>witness cone. This does't bother me any. Who
>>cares if the cone in the sitter has '7' stamped
>>on it, if it gives you the results you want?
>>
>>This doesn't imply 'unevenness', just a common,
>>almost normal, discrepancy between sitter cones
>>and witness cones in that particular application.
>>If you are really bothered by it, you can
>>recalibrate your sitter.
>>
>>The nominal correct bend for a sitter cone
>>is 90º. If it's not, that should be corrected.
>>For the 90º bend, there is a template you can
>>get from most suppliers, but it isn't really
>>necessary; the adjustment can be done by eye
>>and readjusted based on the results of firing.
>>If it is 90º, then you can adjust the sitter
>>to shut off at a greater or lesser degree of
>>bending. Since yours shuts off at 'almost ^6'
>>when a^7 is in the sitter, you want it to not
>>shut off 'til a greater bend is reached, so
>>that a ^6 will shut it off, but only after
>>true ^6 heat-work has been reached.
>>
>>To do the actual adjustment, look on the outside
>>of the sitter. On the deadfall flap (the bit
>>that you lift up and set to start the firing,
>>and which flops down at the end) you will see a
>>tiny set screw. This can be turned with a small
>>screwdriver (like for eyeglasses) or a knife tip.
>>Above that (below, when in the 'off' position)
>>is a piece of flat metal sticking out of the
>>main flap. This is what the set screw holds in
>>place. Sliding that tab of flat metal further
>>into the flap will make the sitter shut off
>>at a flatter bend in the cone (cooler). Sliding
>>that metal tab further out will make the sitter
>>shut off at a greater angle in the cone (hotter).
>>
>>Very small sdjustments make big differences.
>>You can fine-tune your firings to a high
>>precision, a little hotter or cooler than the
>>nominal cone, or dead on. Not every glaze fires
>>best at exactly some nominal cone number,
>>though, and why should it? Just because we
>>don't have an efficient way of saying, say,
>>^5-3/4, doesn't mean it might not be perfect
>>for what some particular glaze requires.
>>
>>(Before adjusting the sliding tab, tape it
>>into place! Otherwise, when you loosen the
>>set screw, the tab will just slide freely and
>>you'll lose track of where it started out.)
>>
>>So, you can do this and recalibrate your sitter,
>>or not. Personally, I wouldn't bother. You have
>>more flexibility and accuracy by using witness
>>cones to judge when to shut down, and you can
>>fire a little bit hotter or cooler as the notion
>>takes you without recalibrating the equipment.
>>When I fire to ^6, I put a ^8 in the sitter,
>>and use it solely as a fail-safe, to shut it
>>down if I get called away or incapacitated,
>>not as the absolute determiner of the correct
>>heat-work.
>>
>>Not everyone can be there for the end of a
>>firing, such as teachers who have to fire
>>after school, but if you are in your own
>>studio, why not? Why abdicate such an
>>important step to a gadget, even one as
>>simple and reliable as a kiln sitter? Witness
>>cones are cheap insurance against bad firings.
>>I don't mind using the sitter to shut down a
>>bisque fire, where I don't really care about
>>precision, but I'd rather make the call
>>myself on a glaze firing.
>>
>>Safer, too. A watched kiln never overfires;
>>mechanical failure is irrelevant if you are
>>there to pull the plug.
>>
>>
>> -Snail
>>
>>______________________________________________________________________________
>>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.
>
>______________________________________________________________________________
>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.
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asim mahmood on tue 7 nov 06
Hi Ron Roy,
If you recall, I am the one who after purchasing MC^6 out of
my very tight budget declared it as " Poor Man's Treasure " and it has
proved it. I am a self taught potter and did not have the idea of soaking
earlier but now I know how it relates to glaze and what slow cooling means.
Definitely I am going to act upon your advice and pin point the cool spot in
my kiln once for all in the next firing to manipulate with the inside temp
but it never struck me earlier!!!!!!!!!!!!!!!!!! Today I will be going home
much wiser. I wish instead of one I have two lives one for normal living and
other exclusively for Clay Yoga. Thank you once again.
Asim Mahmood.
>From: Ron Roy
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: Glaze Firing ^ 6
>Date: Tue, 7 Nov 2006 13:56:34 -0500
>
>Hi Asim,
>
>Just to add a little - soaking is a very good way to even out a firing -
>and slowing down before the end is almost as good.
>
>I second the advice to get a pyrometer - don't trust it to tell you the
>actual temperature - use it to tell if you are increasing, holding or
>losing temperature.
>
>The best thing would be to find out which combination of switch setting
>would hold temperature the best - keeping in mind - where the kiln is
>coolest - to have the switch for that section on high.
>
>Put cones at every level in your kiln to see where the hot and cold spots
>are - once you know that you won't need as many - I only use one cone now
>but I have a two zone controller - that and an element in the floor is the
>best system I have ever used.
>
>RR
>
>
>
> >From: "asim mahmood"
> >So what is the best way to
> >achieve a uniform ^ 6 temp inside and at the sitter? Is
> >there some thing
> >wrong with the sitter? Or does it needs calibration? If so
> >how and from
> >where.
> >b. How to achieve soaking after attaining ^ 6 temp as
> >cone in the sitter
> >(^6) would not allow you to do that.
> >c. How to achieve gradual cooling down with manual
> >control system.
> >----------------
> >
> >It is normal for the Kiln Sitter to require a hotter cone
> >than the witness cone. I wouldn't worry about that.
> >
> >You will need a firing gauge to calibrate the Kiln Sitter.
> >It is a disk that slides onto the two cone supports. The
> >actuating rod goes through a center hole in the firing
> >gauge. With the gauge in place, adjust the trigger (on the
> >outside of the Kiln Sitter) so that it barely touches the
> >release claw. This is much easier to do than to describe.
> >You might find the disk in the instruction packet that came
> >with the kiln.
> >
> >To soak after the Kiln Sitter shuts off, raise the weight,
> >press in the plunger, and gently lower the weight. Turn the
> >switches to a medium setting. You will need to shut off the
> >kiln manually since this procedure by-passes the Kiln
> >Sitter. To do a slow cooling, lower the switch setting.
> >
> >To hold and soak accurately, you will need a pyrometer.
> >Otherwise you can estimate the temperature by noting the
> >color of the kiln interior.
> >
> >Sincerely,
> >
> >Arnold Howard
> >Paragon Industries, L.P., Mesquite, Texas USA
> >ahoward@paragonweb.com / www.paragonweb.com
> >
> >______________________________________________________________________________
> >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
>RR#4
>15084 Little Lake Road
>Brighton, Ontario
>Canada
>K0K 1H0
>
>______________________________________________________________________________
>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.
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