FAY & RALPH LOEWENTHAL on mon 12 aug 96
Hi all on CLAYART. My wife, Fay, and I are potters and have a small potters'
supply business which we run from home. We live in Port Elizabeth the "Friendly"
city of South Africa. Some would like to add "Windy" as well, but we are not as
bad as some other coastal cities.
The problems I am having with 1 kiln (5.48 cubic feet) is as follows: The last
firing the bottom overfired, the middle was sort of OK and the top the glaze did
not melt. I measured the amperage which was almost 50 amps. We have a 220/240
volt supply it means the kiln was using almost 11kilowatts an hour, which is far
higher than what I think it should be. The 10 elements are Kanthal A1 wire 2mm
(milimetre) thick. They each consist of 80/90 coils with a interior diameter of
12mm (half inch), Which makes them about 2.5 to 3 metres long. They are arranged
in two parallel series of 5. I have tried putting in elements with more coils
and made of 2.4 mm A1 Kanthal wire, but then the kiln took forever to reach
bisque temperature (950 C). I am at my wits end.
To: Whoever was looking for a Turquoise Glaze. I have 2 recipes for glazes a
pottery teacher gave me. We call them Brilliant Matt Purple and Brilliant Matt
Turquoise. They are volatile so be very careful with your kiln shelves. There is
Barium Carbonate in the recipes, so they are poisonous whilst in the raw state.
Please wear masks and gloves and if possible work at an extractor fan. I just
put a normal fan pointing out the window and work behind it. I hear from
production potters that Barium can leach thru your skin. Be careful and practise
Good Safety Habits.
Brilliant Matt Turquoise Brilliant Matt Purple
% %
Nepheline Syenite 55 19
Silica 7 10
Barium Carbonate 26 40
Lithium Carbonate 2 5
China Clay / Kaolin 6 19
Copper Carbonate 4 7
As you can see they both use the same ingredients, but in different proportions.
I have a friend / customer (they usually become friends) who is a production
potter (with a 200 cubic foot parafin fired kiln), who uses the BMT and is
delighted with it. He fires to cone 6 (1200/1220 C)You have to watch your
application thickness to get the result you want. We have fired the BMP from 950
C to almost 1300 C with different results but always pleasantly surprised. Do
not expect consistancy with these glazes.
Alan Ambrose on wed 14 aug 96
Hi,
Your kiln is doing something odd. They tend to be hotter at the top and
cooler at the bottom. One thing that would cause the reverse is a broken element
or bad connection at the top of the kiln. Since your problem is one of heat
distribution (some bits are hot, some cooler) rather than total quantity of heat
(can't get to temperature) the element layout and insulation layout are the
important things. Maybe your kiln lid (I'm assuming you have a top loader)
doesn't seat too well.
Other things to try - checking exact difference with cone packs placed middle,
top and bottom. Switch elements at different levels with different regulators
(if possible). It is unlikely to be due to element layout or size unless the
kiln was very badly designed. I recommend Harry Fraser's book "The Electric
Kiln" for all sorts of good electric kiln explanation, including some basic
element calculations. By the way 11kW/50A is on the high side but not
unreasonable for 5.5 cubic feet. Harry Fraser suggests 1.7 kW per foot for 4-12
cubic feet (9.4kW for 5.5 feet). This is for stoneware with (I think) 2.5 inch
bricks.
Regards, Alan
Tish Cook on thu 5 nov 98
Hi to all of you out there,
I am a new subscriber and thought I would try to get some info. on the
problem I have been having with my propane fired downdraft California
kiln. My last firing took 17 hours to reach cone 10, but I really want
to go to cone 11 at least to the 2 or 3 o'clock position. I would like
the firing to last 8 to 10 hours because I use a rutile glaze that runs
badly if fired too long. It seems to just stall and won't go any
higher. I just replaced my bag walls and repaired a few minor cracks
but it didn't seem to help. Any suggestions???
Lana Reeves on fri 6 nov 98
Tish-- Try turning the gas DOWN when it stalls. Less gas = more oxygen, gas
can burn more efficiently therefore hotter. You're not saying what cone
you're at when you stall. If it's around ^7 or 8, it probably won't hurt
your glazes to ease off into light reduction. Lana
-----Original Message-----
From: Tish Cook
To: CLAYART@LSV.UKY.EDU
Date: Thursday, November 05, 1998 9:47 AM
Subject: Kiln problems
>----------------------------Original message----------------------------
>Hi to all of you out there,
>I am a new subscriber and thought I would try to get some info. on the
>problem I have been having with my propane fired downdraft California
>kiln. My last firing took 17 hours to reach cone 10, but I really want
>to go to cone 11 at least to the 2 or 3 o'clock position. I would like
>the firing to last 8 to 10 hours because I use a rutile glaze that runs
>badly if fired too long. It seems to just stall and won't go any
>higher. I just replaced my bag walls and repaired a few minor cracks
>but it didn't seem to help. Any suggestions???
>
Marc Ward on fri 6 nov 98
Hey folks,
Someone said;
<<to go to cone 11 at least to the 2 or 3 o'clock position. I would like
the firing to last 8 to 10 hours >>>
Speed is a function of BTU per hour per cubic feet. Not enough, and the kiln
takes too long. On some occasions, too many BTU's can stall a kiln also. Now,
the BTU's per hour can be affected, in your case, by low regulator capacity,
too small a propane source, excessive distance between kiln and tank,
inadequate burners, the wrong burners/orifice, altitude, too much tertiary
air, not enough secondary air, wrong stack height, ect. Simple questions like
this don't have simple answers....there's just too many variables. Feel free
to give me a call to discuss your situation.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
June Perry on fri 6 nov 98
Make sure your burners/orifices are really clean and make sure that you're not
over reducing at the end. Putting the kiln in neutral or oxidation at the end
(between cone 9-10) may help you reach temperature sooner.
You might also consider giving it a coating of ITC - 100 which can help the
insulating qualities a bit.
Is it a commercial kiln that you're using or one you built yourself? Is there
enough air space around the burner ports,is the flu the right size in relation
to the port openings,etc.
Regards,
June
Jennifer Boyer on sat 7 nov 98
Hi Tish,
Coating my old softbrick gas kiln with ITC, and filling cracks helped, but
I had the most dramatic improvement in firing time when I added 2 inches of
fiberfax blanket to my arch.
I just shut off my kiln at cone 10 today after firing for 5 hours on one
burner overnight, then usual turn ups starting at 6 AM and ending at 4:45
PM! Before ITC and Fiberfax, I was firing from 5 AM to 9 PM after
candling. Anyone against candling?? I don't want to hear it !
;-)
Jennifer with 2 more glaze kilns to go before Nov 18......
Tish Cook wrote:
> ----------------------------Original message----------------------------
> Hi to all of you out there,
> I am a new subscriber and thought I would try to get some info. on the
> problem I have been having with my propane fired downdraft California
> kiln. My last firing took 17 hours to reach cone 10, but I really want
> to go to cone 11 at least to the 2 or 3 o'clock position. I would like
> the firing to last 8 to 10 hours because I use a rutile glaze that runs
> badly if fired too long. It seems to just stall and won't go any
> higher. I just replaced my bag walls and repaired a few minor cracks
> but it didn't seem to help. Any suggestions???
--
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer jboyer@plainfield.bypass.com
Thistle Hill Pottery
Vermont USA
http://www.vermontcrafts.com/members/JenniBoy892.html
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Chess Denman on mon 9 nov 98
Late in the firing are you firing with the damper too closed?
Earlier in the firing are you firing with the damper too open?
Chess
-----Original Message-----
From: Jennifer Boyer
To: CLAYART@LSV.UKY.EDU
Date: 08 November 1998 01:59
Subject: Re: Kiln problems
>----------------------------Original message----------------------------
>Hi Tish,
>Coating my old softbrick gas kiln with ITC, and filling cracks helped, but
>I had the most dramatic improvement in firing time when I added 2 inches of
>fiberfax blanket to my arch.
>I just shut off my kiln at cone 10 today after firing for 5 hours on one
>burner overnight, then usual turn ups starting at 6 AM and ending at 4:45
>PM! Before ITC and Fiberfax, I was firing from 5 AM to 9 PM after
>candling. Anyone against candling?? I don't want to hear it !
>;-)
>Jennifer with 2 more glaze kilns to go before Nov 18......
>
>
>Tish Cook wrote:
>
>> ----------------------------Original message----------------------------
>> Hi to all of you out there,
>> I am a new subscriber and thought I would try to get some info. on the
>> problem I have been having with my propane fired downdraft California
>> kiln. My last firing took 17 hours to reach cone 10, but I really want
>> to go to cone 11 at least to the 2 or 3 o'clock position. I would like
>> the firing to last 8 to 10 hours because I use a rutile glaze that runs
>> badly if fired too long. It seems to just stall and won't go any
>> higher. I just replaced my bag walls and repaired a few minor cracks
>> but it didn't seem to help. Any suggestions???
>
>
>--
>~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
>Jennifer Boyer jboyer@plainfield.bypass.com
>Thistle Hill Pottery
>Vermont USA
>http://www.vermontcrafts.com/members/JenniBoy892.html
>~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
>
Elias Portor on sun 14 mar 99
I have a small cress kiln that has the thumbwheel, and speed control box
on it. The thumbwheel is no longer turning independently during firing
therefore nothing goes to full fire, can anyone tell me what might be
wrong with the kiln mechanisms. It will fire fine if I turn the
thumbwheel manually and watch the cones carefully. Otherwise if I put
the thumbwheel setting on one it will stay there forever until the kiln
shuts off. Is it the thumbwheel or the speed box that could be not
working? E. Portor
Kim Marie on fri 19 oct 01
I have a L & L electric J230 kiln. It wasn't reaching temp ^6. I've
changed the elements and also had to change 2 of the 3 jump wires. I ran
the first load after repairs and it was a beautiful load. Fired it again
yesterday. It ran ALL night and never reached temp. Any ideas on why?
Kim Marie
in Spafford NY with other headaches now
Jonathan R Smith on fri 19 oct 01
Kim Marie wrote:
> I have a L & L electric J230 kiln. It wasn't reaching temp ^6. I've
> changed the elements and also had to change 2 of the 3 jump wires. I ran
> the first load after repairs and it was a beautiful load. Fired it again
> yesterday. It ran ALL night and never reached temp. Any ideas on why?
>
> Kim Marie
> in Spafford NY with other headaches now
>
Check the fuses,
I had some on my wife's American Beauty get wierd,
and it fired to temp after replacement.
The 60A cartridge fuses were crystallized inside,
but still passed a continuity test.
JOn
Penni Stoddart on thu 13 mar 03
Hi all,
I am being VERY frustrated with a new-to-me-kiln. I'm hoping someone out =
there can help.
Here's the story......
Over fired the kiln 2 weeks ago (went to about cone 12 - all the witness =
cones etc were melted to puddles and my cone 6 clay was bloated.) I =
figured out today as elements were breaking in my hands that I pooched =
the elements.
Did a glaze firing last Saturday - did not get to temp. I tried again =
Monday (after checking that all elements were working etc etc) still =
stalled at 1700 (got the new pyrometer working)
Drove 200km to Toronto yesterday to pick up new elements - an entire =
set! After getting rid of both kiddies today I installed said elements. =
Everything seems hunky dory. NOT!
Turned the kiln on low (only 2 elements - seems to be working fine). =
Left to watch daughter's circus camp show, came home to find kiln light =
on but no one is home!!! Not one element is on but the kiln has not =
switched off.
Okay - I'm frustrated, stumped and feeling foolish.
HELP!
What the &*$# did I do wrong this time? What should I change, re-wire, =
check, screw with blah blah blah........??????
The stuff in there now is student work and has been through 2 (& 1/2) =
failed glaze firings - is it still okay to fire it again? Or will I ruin =
things drastically?
Your opinions and advice are greatly appreciated.
Penni
where today, more then just the extra snow we got here in London, Ont. =
is bugging me.
Lily Krakowski on fri 14 mar 03
Penni, dear. This is just dreadful, terrible, and so on. It happens to all
of us.
It seems likeliest from reading your description that something beyond the
elements got cooked when you overfired. So when you turned the kiln on,
after a while that thing disconnected or broke or whatever.
You can run around and drive yourself crazy. I don't think so. There are
potters in/near London, O. and you might give one a call and say: Who is
your kiln electrician.
Call the electrician. Have him/her come and check out the entire thing---
I know this costs money: but it will save you time, and sanity, and moe
important it will be done once and for all.
As to dangers of refiring: in my experience they are minimal, if the thing
never got to temp. but a lot depends on variables which I cannot guess at
from here.
Penni Stoddart writes:
> Hi all,
> I am being VERY frustrated with a new-to-me-kiln. I'm hoping someone out there can help.
> Here's the story......
> Over fired the kiln 2 weeks ago (went to about cone 12 - all the witness cones etc were melted to puddles and my cone 6 clay was bloated.) I figured out today as elements were breaking in my hands that I pooched the elements.
> Did a glaze firing last Saturday - did not get to temp. I tried again Monday (after checking that all elements were working etc etc) still stalled at 1700 (got the new pyrometer working)
> Drove 200km to Toronto yesterday to pick up new elements - an entire set! After getting rid of both kiddies today I installed said elements. Everything seems hunky dory. NOT!
> Turned the kiln on low (only 2 elements - seems to be working fine). Left to watch daughter's circus camp show, came home to find kiln light on but no one is home!!! Not one element is on but the kiln has not switched off.
> Okay - I'm frustrated, stumped and feeling foolish.
> HELP!
> What the &*$# did I do wrong this time? What should I change, re-wire, check, screw with blah blah blah........??????
> The stuff in there now is student work and has been through 2 (& 1/2) failed glaze firings - is it still okay to fire it again? Or will I ruin things drastically?
> Your opinions and advice are greatly appreciated.
>
> Penni
> where today, more then just the extra snow we got here in London, Ont. is bugging me.
>
> ______________________________________________________________________________
> 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.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Brian Haviland on fri 14 mar 03
HI Penni..
I don't know what kind of controller you have on your
kiln. Sitter , electronic controler,ect .ect... But if it is a kiln
sitter you need to check the contactor inside the sitter and see if
contacts are burnt ..Please have a pro look at it if you are not versed in
electronics contacts . taking an ohm reading accross them when you manually
close them.(PLEASE MAKE SURE ITS UNPLUGED FIRST) IF YOU SHOW THEM TO BE
OPEN THEY NEED REPLACED.If this is an electronic controler solid states are
a total diffrent story and can only be troublshot when you have power to
them (GET A PRO. TO DO THAT) But anyway be careful. And no your student
work should be ok . As long as you did not overfire it.... just test fire
the kiln with cones in place before you put more work into it again.
Good luck and be careful !!!!!!!
At 10:36 PM 3/13/03 -0500, you wrote:
>Hi all,
>I am being VERY frustrated with a new-to-me-kiln. I'm hoping someone out
>there can help.
>Here's the story......
>Over fired the kiln 2 weeks ago (went to about cone 12 - all the witness
>cones etc were melted to puddles and my cone 6 clay was bloated.) I
>figured out today as elements were breaking in my hands that I pooched the
>elements.
>Did a glaze firing last Saturday - did not get to temp. I tried again
>Monday (after checking that all elements were working etc etc) still
>stalled at 1700 (got the new pyrometer working)
>Drove 200km to Toronto yesterday to pick up new elements - an entire set!
>After getting rid of both kiddies today I installed said elements.
>Everything seems hunky dory. NOT!
>Turned the kiln on low (only 2 elements - seems to be working fine). Left
>to watch daughter's circus camp show, came home to find kiln light on but
>no one is home!!! Not one element is on but the kiln has not switched off.
>Okay - I'm frustrated, stumped and feeling foolish.
>HELP!
>What the &*$# did I do wrong this time? What should I change, re-wire,
>check, screw with blah blah blah........??????
>The stuff in there now is student work and has been through 2 (& 1/2)
>failed glaze firings - is it still okay to fire it again? Or will I ruin
>things drastically?
>Your opinions and advice are greatly appreciated.
>
>Penni
>where today, more then just the extra snow we got here in London, Ont. is
>bugging me.
>
>______________________________________________________________________________
>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.
william schran on fri 14 mar 03
Penni wrote:Not one element is on but the kiln has not switched off.>
Penni - You replaced the elements, but only turned on low. Have you
turned all elements on high until each one begins to turn red? That's
the way to check they're all working.
As to why your "kiln light" is on but no elements on - could be any
number of things. Could simply be a pilot light that comes on if
power is coming into kiln but element switches are turned off. Check
your kiln manual to see if it explains. Without the brand of kiln and
more information it's hard to give a more specific answer.
Bill
mel jacobson on fri 21 may 10
big, tall bag walls are sort of out of fashion. i have never had a bagwall=
in
any kiln i build.
just to test that theory, i have been firing
pots on bricks in my flame way.
they look just like all the other pots in the firing. direct flame on
them.
don't let your bag wall become a heat dam. just keeping
the heat away from your pots. and, ask yourself the question:
`what the hell is that bag wall doing in there?...defend it.` and, you
have to heat all those bricks with every firing. why are you heating
50 bricks. they are not doing anything in your kiln. just consider
the cost of heating stuff that you don't need.
bag walls are fine when you want to keep sticks and
crap off your pots, but in a gas kiln, what is it doing?
others have given great advice, listen to them.
start that kiln and kick it in the ass. turn it to high
and let it go, you can turn it down after it hits cone 8.
remember, high gas pressure moves the heat around,
same for low. find out the difference. how does turbulence
move the heat, and where?
if i fire with really low pressure, the heat rises.
big fire, heat at the bottom. so that is why i turn
my kiln way down at the end. it evens out very nicely.
i also have a brick in the flame way and use it in different
configurations to move the heat around...read nils' book.
he gives a diagram and explains tuning bricks.
with a bit of knowledge and experimentation, you can hit four
sets of cones over at the same time. cone 10 X 4.
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
new book: http://www.21stcenturykilns.com
alternate: melpots7575@gmail.com
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