GSM_ENT on fri 27 aug 99

Hi Wendy!

Kiln elements do wear with use, particularly if you do reduction fires, and
high firing. Although there is no specific formula a guidelien is 10% over
the resistance of the heating elements. Resistance is measured in Ohms and
you would need an Ohm Meter to take the reading. Everyone should maintan a
Firing Log or Firing Record, this will not only tell you the number of
firings you have done but also assist you in calibrating the kiln sitter
which should be done every 20 firings. WP Dawson, manufacturers of the Kiln
Sitter, recommend that if you are a business and fire repeatedly, to change
the tube assembly every year. Hobbyist should change it every 2-3 years.
Calibration of the kiln sitter requires a calibration gauge which came with
your kiln when new. Most people throw this gauge away because they believe
it is just a packing item. In your manual there should be a section on
calibration of the kiln sitter, if not pls let me know and I will send you
some.

In order to obtain the maximum number of firings from you heating elements
the very first firing should be "an oxidation firing" for the heating
elements. With the kiln totally empty, no peephole plugs and the lid vented
during the low and medium portion of your firing schedule, fire the kiln to
cone 01. Lab. testing has determined that any cooler firing doen not do the
job properly. During the high segment close the lid but do not install the
peephole plugs. The second firinjg should be a "test firing" using the
average number of shelves and posts you intend to use. The cone should be
the average cone you intend to use. Testing must be done at the hottest and
coldest cones to be used. Calibration is made via the firing cone. It is
better to use "cones" vs bars as the shape of the cone allows you to
position the firing cone towards the thicker part of the cone thus achieving
an approximate 1/2 cone hotter. Witness cones, in set of three -one hotter
and one colder in addition to the cone value of the firing-must be used in
all firings. If during the first test firing the kiln fires colder (the
witness cone did not achieve the 6 o'clock position, then you must refire in
a second test firing. This time position the firing cone towards the thicker
side as explained before. If this does not do it then do a third test firing
but this time us a firing cone of a value hotter that what is intended to be
reached on the shelf. It is normal for larger kilns to have a "Delta" or
difference between the firing cone and the witness cones.

I hope I shed some light on the subject. For more information I suggest:
reading the kiln manual, and joining the Orton Firing Foundation (now Orton
Firing Institute).

Cordially,

Manuel R A "Tony" Diaz Rodriguez
MAJ., US Army (Ret.)
Master Kiln Repair Technician




-----Original Message-----
From: Wendy Hampton
To: CLAYART@LSV.UKY.EDU
Date: Thursday, August 26, 1999 8:49 AM
Subject: Kiln elements


>----------------------------Original message----------------------------
>I have had my kiln for a few years and have fired it a little over 100
times.
> I am noticing that it takes about an hour longer for it to fire than it
used
>to. I am assuming that the elements are wearing out but don't know when I
>should replace them. Is there some kind of maintenance schedule that most
>people keep?
>Thanks
>Wendy

wschran@erols.com on sun 29 aug 99

Patsy - The best way to check when to replace elements is to take an
ohm reading. When the elements are down 20% from the reading when they
are new, it's time to replace them. Do I do this? No. I've got a school
situation with 5 kilns in constant use. When do I replace them? When
the time required to reach temperature becomes unreasonable (beyond the
time for me to go home at night - No I don't walk away and expect the
kilns to shut off automatically). Others with more critical firing
schedules (crystalline glazes, etc.) will monitor their kilns more
carefully. I'm considering coating my next new set with an ITC coating.
Anybody have any experience with this?
Bill

Susan Fox Hirschmann on tue 31 aug 99

My own experience has been that i change the elements every 50 high
firings.(Since i keep accurate records of all firings, it is not a problem
knowing when i approach the 50 mark) Most of the time , when they are
changed the elements are pretty brittle and about to break about that time
anyway.
So i try and do it before i have a problem.
Chances are, that if your firings are starting to slow down, that it is
indeed time for new elements.
hope that helps!
susan
in delightfully cool northern virginia


s

David Hewitt on thu 2 sep 99

If it is of interest I achieved the following with my last set of
elements in a Cromartie CTL 75 top loader.
Biscuit to 1000oC 71
Cone 6 glaze firings 61
Cone 8 glaze firings 60
On-glaze lustre - 800oC 13
____
205
With my current set, the mix is probably similar, I have reached 114 and
going strong.
David
In message , Susan Fox Hirschmann writes
>----------------------------Original message----------------------------
>My own experience has been that i change the elements every 50 high
>firings.(Since i keep accurate records of all firings, it is not a problem
>knowing when i approach the 50 mark) Most of the time , when they are
>changed the elements are pretty brittle and about to break about that time
>anyway.
>So i try and do it before i have a problem.
>Chances are, that if your firings are starting to slow down, that it is
>indeed time for new elements.
>hope that helps!
>susan
>in delightfully cool northern virginia
>
>
>s
>

--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm

Susan Fox Hirschmann on thu 2 sep 99

David,
I appreciate your sharing that info with me.
Because i often soak at cone 10 for 4 hours and then fire down, and my 10 cu.
ft.s sometakes 18-24 hours to get to cone 10, (I am doing some larger
porcelain plates that seem to require slooooowwwww going up and down)---I
feel there is definitely more stress on the elements, and towards the
50th-60th glaze firings the kilns seem to be "cranking" to meet the temps.
When i did a "normal" glaze firing, slowly going up but without any kind of
soak and letting the sitter cut it off, i found that my elements appeared to
last for more firings.
I did not state in that i probably also do about 100 bisques interspersed
with the glaze firings.
What brand of kiln do you have that can give you such qunaitity of (I am
assuming good) firings with the same elements?
always happy to share information and understand what others are doing.

susan fox hirschmann
annandale, virginia

John Jensen on thu 2 sep 99

I fire to 2135 F in Skutts. I fire just about every day. I have a km1027
and two km1227's. There is always one of the three firing if not two or all
three. I've been getting about 200 to 250 firing before it won't reach
temperature. So far I've been replacing elements with factory replacements,
since they were covered under my 2 year warranty. Starting sometime next
spring I'll be buying my own elements. So I've been interested in the
Euclid option.

John Jensen, Mudbug Pottery, Annapolis

Tom Wirt on fri 3 sep 99

Subject: Re: Kiln elements


> ----------------------------Original message----------------------------
> My own experience has been that i change the elements every 50 high
> firings.(Since i keep accurate records of all firings, it is not a problem
> knowing when i approach the 50 mark) Most of the time , when they are
> changed the elements are pretty brittle and about to break about that time
> anyway.
> So i try and do it before i have a problem.
> Chances are, that if your firings are starting to slow down, that it is
> indeed time for new elements.
> hope that helps!
> susan


Susan.....I'm sure you've had this from others but, your element life seems
way short. We used to do both bisque and glaze firings in our electrics, (2
28x27 Cone Arts and a 1027 Skutt) cone 10 generally twice a week firings and
would normally replace elements maybe once a year unless glaze got on one.

Now we're dipping in ITC 213 and doing mostly just bisque, but elements
1-12/ years old show no sign of deterioration and they are still flexible.
Suggest you give Alice a call and check it out. 1-904-285-0200.

Tom Wirt

Susan Fox Hirschmann on fri 3 sep 99

In a message dated 9/3/99 9:13:18 AM EST, claypot@hutchtel.net writes:

<< Susan.....I'm sure you've had this from others but, your element life seems
way short. We used to do both bisque and glaze firings in our electrics, (2
28x27 Cone Arts and a 1027 Skutt) cone 10 generally twice a week firings and
would normally replace elements maybe once a year unless glaze got on one.

Now we're dipping in ITC 213 and doing mostly just bisque, but elements
1-12/ years old show no sign of deterioration and they are still flexible.
Suggest you give Alice a call and check it out. 1-904-285-0200.

Tom Wirt >>


Thanx tom!
What i probably failed to add was that i am also doing about 100 bisques, but
that my glazes firings are REALLY slow, with several hour soaking at 10 and
then firing down. Even in my 10 cu ft. kilns, i tend to do 20 -24 hour
firings, and do not let kiln setter cut it off, but rather, closely approach
10, soak, and then fire it down manually. (I found that works best for me on
large porcelain PLATES and other thin porcelain wall pieces--that is the
reason for my "unusally" long firings.
So now that you know my methods to my own "madness" over here, you wil
probably realize why at about 50-60 cone 10's, the elements are cranking to
reach temperature, and the firings do slow down. and that is why i change
them at that point. If i were :"merely firing up, letting the sitter cut it
off, etc, i of course s\would have shorter firer, putting less "strain" on
the elements.

I do appreciate your advise....always more to learn, huh?
susan

susan fox hirschmann
annandale, va

T. Howard on sun 22 oct 00

Thank you for answer to my Barnard Clay question. Here is another query-
about the flattening of kiln elements - does anyone know if opening the kiln
"early" i.e. before it has really cooled down- causes elements to flatten?

mudlark on mon 9 apr 01

Was talking with a friend and she told me her local kiln repair guy said that kiln
elements will pop out of the grooves in the walls do to firing to only low temps
(bisque) all the time. Now she had two of their kilns elements replace and only
one had this happen. This is not my experience firing to 03 all the time. Anyone
hear of this?

--
Clyde Tullis
Mudlark Pottery
320 G Street
Salida, CO 81201
719-539-1299
mudlark@chaffee.net
http://www.mudlarkpottery.com

Arnold Howard on wed 11 apr 01

Yes. Fire to cone 05 occasionally to keep the elements in the
grooves. An exception: kilns with horizontal grooves that do not
angle downward.

Arnold Howard
Paragon

--- mudlark wrote:
> So you are recomending to fire past 05 at least once to "set" the
> elements in
> their grooves?
>
> Arnold Howard wrote:
>
> > When elements are fired past cone 05, they soften to the point
> > where they cannot support their own weight. Thus, they conform
> to
> > the shape of the element grooves. This prevents element
> bulging.
> >
> > If your elements bulge out of their grooves, you can work them
> back
> > into place with a propane torch (available from a hardware
> store
> > for about $20).
> >
> > 1. Unplug the kiln.
> >
> > 2. Heat the bulging section until the element becomes pliable.
> >
> > 3. With long-nose pliers, squeeze the coils together slightly.
> >
> > 4. When the element is positioned above the groove, use a blunt
> > knife to press it into the groove.
> >
> > Note: if the element cools and you try to squeeze the coils
> > together, you will break the element. The element does not have
> to
> > be red hot, but must be hot enough to be pliable. You can feel
> that
> > through the handles of the pliers.
> >
> > Arnold Howard
> > Paragon
> >
> > --- mudlark wrote:
> > > Was talking with a friend and she told me her local kiln
> repair
> > > guy said that kiln
> > > elements will pop out of the grooves in the walls do to
> firing to
> > > only low temps
> > > (bisque) all the time. Now she had two of their kilns
> elements
> > > replace and only
> > > one had this happen. This is not my experience firing to 03
> all
> > > the time. Anyone
> > > hear of this?
> > >
> > > --
> > > Clyde Tullis
> > > Mudlark Pottery
> > > 320 G Street
> > > Salida, CO 81201
> > > 719-539-1299
> > > mudlark@chaffee.net
> > > http://www.mudlarkpottery.com
> > >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Get email at your own domain with Yahoo! Mail.
> > http://personal.mail.yahoo.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.
>
> --
> Clyde Tullis
> Mudlark Pottery
> 320 G Street
> Salida, CO 81201
> 719-539-1299
> mudlark@chaffee.net
> http://www.mudlarkpottery.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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Get email at your own domain with Yahoo! Mail.
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Joe Brecha on mon 23 jan 06

In regards to sizing elements for kilns. The easiest way to determine =
this is to check to see how many amps are required by commercial kilns =
of similar size. Test kilns this size are generally made to fire on 120 =
volts. In a household situation you are often restricted to a 20 amp =
circuit. You will find that the max amps you could put on a 20 amp =
breaker on a 120 volt circuit would be about 16 or 17. Multiply amps by =
volts and you will get the watts required. 17 x 120 =3D2040 watts. =
This kiln element would commonly be made with 16 guage wire. 14 guage =
would require two elements in parallel. This would require so much wire =
it would be difficult to fit into the space. Joe Brecha