Jonathan Kaplan on thu 7 apr 05
Why any one would waste their precious time and costly electricity to
fire to cone 10 in an electric kiln is baffling to me and just does not
make any sense.
Some things that might be of interest to add to this discussion. I
reviewed electric kilns for Pottery Making Illustrated. There is, I
believe, still some good information in that article. Its probably in
the archives on their web site. You can take it or leave it, but
FYI......
With few exceptions, most electric kilns that we use, eg the top
loaders, are under powered and under insulated. They are particularly
price pointed and as such, you are not going to find these types of
"hobby kilns" productive to cone 10. Its not going to happen and just
because the tag says they are rated to cone 10 does not mean that you
can do it on a daily basis. They are just not built for that kind of
use. IMHO, firing electric kilns to cone 10 is a waste of money and a
waste of time. You can, fire these kilns to cone 6 day in and day out
and get fabulous results. I never quite understood what the whole thing
is about getting the "reduction look" in an electric kiln anyways.
That's just bad thinking. The electric kiln is a fabulous piece of
equipment and with some knowledge, a kiln controller, a spray booth and
glazes, I don't know why anyone would need anything else. It is a pity
to see all this energy (no pun intended) wasted on the pursuit of the
reduction look in an electric kiln.
If you must have a top loading kiln that fires to cone 10, buy a
Nabertherm. Its huge bang for the buck
There are really good top loading electric kilns in the market place.
You all know the names. For up to cone 6 work, I would look at them all
(with few exceptions and that's my own opinion) as they will all do the
trick. Quite well also.
If you have the money and really have to, again, fire to cone 10 in an
electric kiln get a front loader. Frederikson, Nabertherm, and others
are built for this use. Most people in a home situation don't have the
necessary power to run these puppies. The top loaders , to cone 6, you
can run them every day in your home studio without a problem. Single
phase, 240V 100 amp service. Others available also.
These days, I would not buy an electric kiln without a controller,
mercury relays/contactors, 3" brick, a vent, cool counterweighted lids,
all the bells and whistles etc etc. All the major players have the
goods.
Electric kilns and the work they produce, if, and that's a BIG IF, you
know what you are doing, how to spray, how to layer glazes and use a
cooling cycle, are not in a any way second class citizens. Its just a
pity they have been relegated to such lowly status.
Jonathan
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139
(please use this address for all USPS deliveries)
Plant Location:
1280 13th Street Suite K
Steamboat Springs CO 80487
(please use this address for all UPS, courier, and common carrier
deliveries only!!)
info@ceramicdesigngroup.net
www.ceramicdesigngroup.net
Zuzupetal on thu 7 apr 05
Hey folks,
As an interested novice and someone who can't even rewire a lamp, I've
been following this discussion, feeling intrigued yet a little
despondent as to the limitations of a cone 10 electric. Are all kiln
brands of of recent and current ilk made to similar limited electrical
standards and elements life-spans? Should some be avoided, others
favored, with some considered for value or other reasons? Are there
key elements to look for in good kiln that will favor more cone 10
firings before requiring new elements.
Victoria Cherney,
Montpelier, Vermont
Craig, Do you secretly moonlight as a master electrician?
On Apr 7, 2005, at 2:58 PM, Craig Martell wrote:
> Sam was wondering:
>> Any other ideas for prolonging the life of a high-fire electric kiln?
>
> Hello Sam:
>
> The only other thing I can think of is sufficient insulation. I've
> used
> kilns in the past that had only 2.5 or 3 inch thick walls and they
> really
> struggle to get up to cone 8 and above. If there is sufficient
> insulation
> to cut heat loss the kiln will fire in a reasonable amount of time and
> this
> will give the elements a break.
>
> I rebuilt an Olympic oval many years ago. It was rated to cone 8 but
> didn't function worth a damn. I had to remortar and repair the lid. I
> made fireclay buttons and put 2600 degree fiber on the lid hot face and
> buttoned it and fastened the buttons with 13 guage Kanthal. I wrapped
> the
> lid with quarter inch aircraft cable and tightened it with turnbuckles
> instead of those wimpy hose clamps. I added Insblok 19 to the outer
> walls
> and totally rewired the kiln. Got rid of the interbox plugs and hard
> wired
> everything to get as much electrical potential as possible and cut
> resistance to all the load lines. This made a big difference in the
> firing
> of the kiln and my pots came out much nicer. All of this was
> suggested by,
> guess who, Kenny Simpson who was also the dude who wound elements for
> me. I think he's real glad that I fire reduction now! 8>)
>
> later on, Craig Martell Hopewell, Oregon
>
> _______________________________________________________________________
> _______
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>
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>
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>
Craig Martell on fri 8 apr 05
Hello Electric kiln enthusiasts:
Jonathan's reasoning about hi fire electric is very sound and I really have
no reason to take exception with what he says.
But sometimes you don't do the work you want by adhering to practical
advice or solid logic. When I started doing hi fire oxidation my reason
for upping the temp was claybodies. There wasn't much time being devoted
to cone 6 potters and cone 6 clays. This was in the mid seventies. The
bodies I used were basically crappy so I went to a higher temp so that I
had a better choice of clays. I didn't have clay mixing stuff in those
days so I was stuck with what I could buy at the supplier. When I went to
cone 10 I had a wider range of choices and the clays were a lot better. I
used P-600 porcelain from Plainsman clays in Alberta. This was a very good
porcelain that fired great in oxidation.
I also learned a lot about working on electric kilns and making them
function better at hi temps. A book that helped a great deal was Electric
Kiln Construction for Potters by Robert Fournier. If you can find that
book and you fire electric, it would be a great help. I guess my thought
here is that even though you're paddling upstream there are things you can
do to make things work better.
I should say too that the Olympic Oval kiln that I was talking about in my
last post was made over 20 years ago. It was one of the first that they
did when the company was still in the Seattle area. I have no idea what
they are like now. I was also pleasantly surprised when Arnold Howard
mentioned that some manufacturers are using 12 guage elements now. 12
guage is REALLY beefy and should last for many firings. I have two
electrics that I bisque in. A Skutt 1027 and a Skutt 1227. They are about
17 years old and still cooking along. Very simple kilns. No
controllers. I use a fluke digital pyrometer and standing senior cone paks
to judge the heat work. They will probably go for another 20 years if I
can hang on that long.
The parting shot is that I think people who are enthusiastic about hi fire
electric should go right ahead and fire. If you want some inspiration
about that type of work and why you should do it, check out Kenneth Chin
Purcell's website. Very nice work.
turn on the juice, Craig Martell Hopewell, Oregon
william schran on fri 8 apr 05
Victoria wrote:>Are all kiln brands of of recent and current ilk made
to similar limited electrical
standards and elements life-spans? Should some be avoided, others
favored, with some considered for value or other reasons? Are there
key elements to look for in good kiln that will favor more cone 10
firings before requiring new elements.<
IMHO, anybody planning on purchasing a sectional top loading kiln
that will be often fired to cone 10 should at the least get a kiln
with 3" walls. I also think heavy duty elements are probably worth
the extra cost.
Realizing element life will be shorter by firing higher - ease of
element replacement should also be considered. That said, I'd go with
an L&L for that reason.
But if one really wants to fire to cone 10, then I'd say spend the
money up front and get a better insulated front loader.
Bill
dannon rhudy on fri 8 apr 05
Jonathan said:
>electric kiln is a fabulous piece of
> equipment ..... pity
> to see all this energy (no pun intended) wasted on the pursuit of the
reduction look in an electric kiln....
>
> Electric kilns and the work they produce, if, and that's a BIG IF, you
> know what you are doing, how to spray, how to layer glazes and use a
> cooling cycle, are not in a any way second class citizens. .....
This is not only an informative post, it is a SENSIBLE post.
It is possible with some effort and research to achieve
glazes of depth, interest, and beauty in ANY kiln, including
electric. Certain glazes may improve at cone 10, but
many don't change visually from 6 to 10. Reduction is
a different matter, but many glazes are actually better in
my experience and observation when they are fired in
oxidation. I have often fired in oxidation when using
gas kilns. It depends on the glaze and your intent for
surface appearance. So - if you test and experiment with
your glazes, you can and will achieve an excellent glaze
palette. Doesn't matter what cone or atmosphere. Just
matters that you be willing to try things until you get what
pleases your eye and suits your work.
regards
Dannon Rhudy
Arnold Howard on fri 8 apr 05
Victoria, the discussion seems to boil down to extra insulation in electric
kilns. When enough consumers demand more insulation, kiln manufacturers will
gladly comply.
About four years ago on Clayart, we discussed extra insulation at length. I
brought up the idea repeatedly at Paragon, and we finally produced a
12-sided model with 1" of block insulation behind the firebrick walls. It
even had an optional lid with block insulation on top. However, so few
people bought the model that we discontinued it.
Actually, it is more feasible to add insulation to square kilns than to
top-loading round kilns. If you want a heavily insulated kiln, a square
design is the direction to go. But since round kilns are more economical to
build, that seems to be what most people demand.
Element wire is getting heavier. As I mentioned in another post, 12-gauge
wire is becoming more common. That may improve element life at cone 10.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net / www.paragonweb.com
From: "Zuzupetal"
> As an interested novice and someone who can't even rewire a lamp, I've
> been following this discussion, feeling intrigued yet a little
> despondent as to the limitations of a cone 10 electric. Are all kiln
> brands of of recent and current ilk made to similar limited electrical
> standards and elements life-spans? Should some be avoided, others
> favored, with some considered for value or other reasons? Are there
> key elements to look for in good kiln that will favor more cone 10
> firings before requiring new elements.
>
> Victoria Cherney,
> Montpelier, Vermont
>> Sam was wondering:
>>> Any other ideas for prolonging the life of a high-fire electric kiln?
>>
>> Hello Sam:
>>
>> The only other thing I can think of is sufficient insulation. I've
>> used
>> kilns in the past that had only 2.5 or 3 inch thick walls and they
>> really
>> struggle to get up to cone 8 and above. If there is sufficient
>> insulation
>> to cut heat loss the kiln will fire in a reasonable amount of time and
>> this
>> will give the elements a break.
>> later on, Craig Martell Hopewell, Oregon
Louis Katz on fri 8 apr 05
I am not an electric kiln user for glazes, at least not in the last 30
years. My early experience and watching Frank Faben's glazes develop in
graduate school and after suggests top me that one approach to electric
kiln glazes to give richness is to use complex colorant combinations.
Frank seemed to favor small amounts of nickel in some glazes, One glaze
i was enamored with had 4 colorants some in quantities like 0.1%
The advice of layering and spraying seem like good pieces of advice to
me, they are old pieces of advice for cone 6 which have stood the test
of time.
Cone 6 reduction is something I have thought of converting my school
studio to. It is on my list of things to try to make happen.
Louis
> surface appearance. So - if you test and experiment with
> your glazes, you can and will achieve an excellent glaze
> palette.
Taylor from Rockport on fri 8 apr 05
Hey Arnold,
I have read through those earler postings on thicker insulation. The main
sticking point for the manufacturer was that round kilns would have to
decrease in interior space with thicker insulation because of all the
retooling that would be necessary for changing cases.
As soon as kiln manufacturers begin with the assumption that 4 inch bricks
or whatever is best will be the material and design all main models around
that, the problem of too few customers will be ended. Kiln buyers are
much much smarter now than they were 20 years ago. We want better
insulation.
I still have the square paragon highfire kiln that I plan on turning into
a raku kiln. It has the one inch backer insulation. I just migh have to
keep that kiln as an electric a poo poo my hopes for raku/reduction firing.
I wonder if older kiln models could me made more efficient by adding
ceramic fiber around bricks and under the case. I don't think that is
going to be a good option however because of where it would have to go.
Bummer.
Taylor in Rockport, TX
On Fri, 8 Apr 2005 08:25:12 -0500, Arnold Howard
wrote:
>Victoria, the discussion seems to boil down to extra insulation in
electric
>kilns. When enough consumers demand more insulation, kiln manufacturers
will
>gladly comply.
>
>About four years ago on Clayart, we discussed extra insulation at length.
I
>brought up the idea repeatedly at Paragon, and we finally produced a
>12-sided model with 1" of block insulation behind the firebrick walls. It
>even had an optional lid with block insulation on top. However, so few
>people bought the model that we discontinued it.
>
>Actually, it is more feasible to add insulation to square kilns than to
>top-loading round kilns. If you want a heavily insulated kiln, a square
>design is the direction to go. But since round kilns are more economical
to
>build, that seems to be what most people demand.
...
Maurice Weitman on fri 8 apr 05
Jonathan Kaplan wrote:
>With few exceptions, most electric kilns that we use, eg the top
>loaders, are under powered and under insulated. They are
>particularly price pointed [...]
Arnold Howard wrote:
>[...] the discussion seems to boil down to extra insulation in
>electric kilns. When enough consumers demand more insulation, kiln
>manufacturers will gladly comply.
and
>Paragon [...] produced a 12-sided model with 1" of block insulation
>behind the firebrick walls. It even had an optional lid with block
>insulation on top. However, so few people bought the model that we
>discontinued it.
Hello, Arnold,
I'm no kiln marketing expert, and I might not be a typical purchaser,
but I went out of my way and spent quite a bit of "extra" money on an
electric kiln that was sufficiently-powered and well-insulated.
I live in California and am subject to PG&E's exorbitant rates, aided
by Enron's fleecing and our government's ineptitude and/or disdain
for energy consumers. Perhaps other parts of the country are and
will be immune to the ridiculous increases of energy costs, but it
seems clear that the efficiency of kilns will only become more
important over time.
It therefore seems to me that kiln manufacturers are missing the boat
in not educating the public in the importance of efficiency and the
false economy of buying a kiln on price alone.
I don't understand why quality kiln manufacturers fight for the
low-price title. Leave that spot for the losers and concentrate on
the educated (or educable) user.
It was great seeing you at NCECA.
Regards,
Maurice
Sam Hoffman on fri 8 apr 05
Johnathan-
I agree 90% with your post...two exceptions:
> Why any one would waste their precious time and costly electricity to
> fire to cone 10 in an electric kiln is baffling to me and just does not
> make any sense.
There are certain clays and glazes that simply do not work in the cone
6 range. (true oilspot, macrocrystalline & microcrystalline,
translucent porcelain, some ash glazes, etc.) Many potters are NOT
simply using electric kilns at high temps to reproduce the reduction
look.
I DO agree with you that it is a huge misnomer that electric kilns are
the most fuel efficient to fire. In fact, compared to gas, oil, and
sometimes even wood, electric kilns can be the worst fuel consumers of
the bunch. This is particularly true when firing to high temperatures.
Is firing an electric kiln to cone 10 a waste of time and energy? Not
if it is a carefully considered decision. If efficiency was the only
consideration for firing, we'd all be doing single-fire pit firing. I
feel that fuel consumption is a very important part of the equation,
but for my pottery, at least, aesthetics is the foremost consideration.
I don't fire my Skutt1227P to cone 10 often, but you can bet that when
I do there is a good reason for it.
> It is a pity to see all this energy (no pun intended) wasted on the
> pursuit of the
> reduction look in an electric kiln.
>
While this is perhaps the case with some potters, I think this
argument is getting a little bit dated. There are many things that can
be done in electric oxidation that can NOT be achieved in reduction;
this is often the focus of electric kiln potters. Ron & John are
developing an exciting palette of cone 6 oxidation surfaces that are
totally unique to that firing range. John Britt has inspired several
of us to explore iron glazes in oxidation, gas and electric. (results
are posted at www.samhoffman.com/glazetests)
For my own work, anyway, if I want a reduction look, then I'll fire in
reduction! I also think there is a lot of potential for cone 10
oxidation in gas kilns. But don't totally discount the possibility of
exploring the high-fire range in electric kilns. Again, it should be a
considered decision.
All of this being said, my preference is for a rip-roaring, smoke
belching, wood-fired anagama. But it sure is fun to explore the
breadth of ceramic technology, is it not?
Firing hot,
Sam
S.L. Hoffman Pottery
Corvallis, Oregon
www.samhoffman.com
Steve Slatin on fri 8 apr 05
Taylor --
IIRC, AIM Kilns was making some electrics with 3"
brick and a 1" insulating blanket a few years
back. Never heard of anyone buying one, though.
Steve Slatin
--- Taylor from Rockport wrote:
> Hey Arnold,
>
> I have read through those earler postings on thicker
> insulation. The main
> sticking point for the manufacturer was that round
> kilns would have to
> decrease in interior space with thicker insulation
> because of all the
> retooling that would be necessary for changing
> cases.
>
> As soon as kiln manufacturers begin with the
> assumption that 4 inch bricks
> or whatever is best will be the material and design
> all main models around
> that, the problem of too few customers will be
> ended.
Steve Slatin -- Pump don't work 'cause vandals got the handles.
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Wes Rolley on sat 9 apr 05
Mitch wrote.
> Excellent input on the ^10 electric kiln. Thank you Johnathan and Danno=
n. When I was a lab rat with Robin Hopper at MISSA in Victoria we had the=
option to fire glaze tests at various temperatures and conditions. There=
was no observable difference between those glazes fired at ^6 and ^9 oxi=
dation.
Mitch, while I can agree with you in general, I have to say that your=20
statement about "nobservable difference" is another of those gross=20
generaliaztions that get into the lore of this craft and end up=20
confusing people. I have glazes with significant observables between=20
Cone 7 at 3:00 and Cone 7 just touching. This is definitely a case=20
where "your milage may vary."
--=20
"I find I have a great lot to learn =E2=80=93 or unlearn. I seem to know =
far too=20
much and this knowledge obscures the really significant facts, but I am=20
getting on." -- Charles Rennie Mackintosh
Wesley C. Rolley
17211 Quail Court
Morgan Hill, CA 95037
(408)778-3024
http://www.refpub.com/
Earl Brunner on sat 9 apr 05
I agree Wes, I have seen glazes where 30 degrees made a huge difference and
that is amazing when you think that 30 degrees is maybe 1.5% of the total
firing temperature at cone 6. Further more, I bet some of the glaze guru
types would tell us that "visible" difference isn't the same thing as
"stable" at that wide of a range either.
Earl Brunner
Las Vegas, NV
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Wes Rolley
Sent: Saturday, April 09, 2005 9:11 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: cone 10 electric-all kilns equal?
Mitch wrote.
> Excellent input on the ^10 electric kiln. Thank you Johnathan and Dannon.
When I was a lab rat with Robin Hopper at MISSA in Victoria we had the
option to fire glaze tests at various temperatures and conditions. There was
no observable difference between those glazes fired at ^6 and ^9 oxidation.
Mitch, while I can agree with you in general, I have to say that your
statement about "nobservable difference" is another of those gross
generaliaztions that get into the lore of this craft and end up
confusing people. I have glazes with significant observables between
Cone 7 at 3:00 and Cone 7 just touching. This is definitely a case
where "your milage may vary."
--
"I find I have a great lot to learn - or unlearn. I seem to know far too
much and this knowledge obscures the really significant facts, but I am
getting on." -- Charles Rennie Mackintosh
Wesley C. Rolley
17211 Quail Court
Morgan Hill, CA 95037
(408)778-3024
http://www.refpub.com/
william schran on sat 9 apr 05
Louis wrote:>Cone 6 reduction is something I have thought of
converting my school
studio to.<
We'll be getting our gas fired kiln up & going for this coming fall.
Have thought we'd do cone 6 reduction, but many of my students want
to do cone 10, so I think we'll try that for a while, do some testing
of cone 6 glazes and compare the results.
Louis - Ceramics Monthly, May 1985, had 2 pages of cone 6 reduction
glazes. Also if you look through the archives, the list Marcia Selsor
posted is there. Contact me off list if you can't access either of
these.
Bill, in Fredericksburg, VA, where spring is here and getting ready
to cut the grass for the second time.
william schran on sat 9 apr 05
Sam wrote:>There are certain clays and glazes that simply do not work
in the cone
6 range. (true oilspot, macrocrystalline & microcrystalline...<
Uh, I do macrocrystalline glazes at cone 6, and get pretty darn good
results. Granted I don't get the same results as my colleagues firing
to cone 10, but I get real close.
Bill
Mitch Kotula on sat 9 apr 05
Excellent input on the ^10 electric kiln. Thank you Johnathan and Dannon. When I was a lab rat with Robin Hopper at MISSA in Victoria we had the option to fire glaze tests at various temperatures and conditions. There was no observable difference between those glazes fired at ^6 and ^9 oxidation.
Mitch
Mitch Kotula
Development Plus
PO Box 2076
Hamilton, MT 59840-4076
406-961-5136 (Home)
406-546-6980 (Cell)
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URL Krueger on sat 9 apr 05
Some rambling thoughts on the subject.
A few numbers to refresh your memory:
Cone 6 = 1220 C (at 60 C / hour)
Cone 8 = 1247 C +27C +2%
Cone 10 = 1282 C +62C +5%
Cone 12 = 1304 C +84C +7%
Isn't it interesting that so much debate occurs over such a
small temperature difference.
Am I wrong in saying that:
At 60 C / hour the difference between Cone 6 and Cone 10 is
one hour. If you have a 10 kw electric kiln running on
high that amounts to 10 kwh of extra electicity
consumption. At $0.10 per kwh that means it costs you
$1.00 more per firing.
If a set of elements costs $300 (a guess) and you get 100
cone 10 firings per set (another guess) then the cost for
elements would be $3.00 per firing. That's not too bad.
However, if you only get 20 firings per set then the cost
would be $15.00 per firing. A significant difference.
What is realistic for element life at cone 10?
I can see, as Mel has stated, that people who make their
living from pottery accept that element replacement is just
part of the cost of doing business. But I also believe
that many people doing pottery as a hobby view their kiln
like a refrigerator, as oppossed to a car. They expect it
to just keep on working without having to do any
maintenance or repair. Therefore, when the elements do
burn out it is a major tragedy. Not a good attitude to
have.
Anyway, just some thoughts. Now, the weeds are calling.
--
Earl K...
Bothell WA, USA
John Rodgers on sun 10 apr 05
Arnold Howard wrote:
> Victoria, the discussion seems to boil down to extra insulation in
> electric
> kilns. When enough consumers demand more insulation, kiln
> manufacturers will
> gladly comply.
>
> About four years ago on Clayart, we discussed extra insulation at
> length. I
> brought up the idea repeatedly at Paragon, and we finally produced a
> 12-sided model with 1" of block insulation behind the firebrick walls. It
> even had an optional lid with block insulation on top. However, so few
> people bought the model that we discontinued it.
>
It appears to me that there are marketing issues here that kiln
manufacturers need to address. The education aspect is key. If the
manuifacturers would have their marketing departments to undertake the
education of the buying public, there would be a shift in the purchasing
toward more energy efficient kilns. It happened in the world of
computers when the Energy Star effeciaency standards came out and people
learned about them and what it meant. Same would be true with the
electric kilns.
Educate the customers. They will go for it.
Build a better mouse trap. They will buy it.
Regards,
John Rodgers
Chelsea, AL
John Hesselberth on sun 10 apr 05
Hi Earl,
Small? The old rule of thumb in chemistry is that 10C can double (or
halve) the reaction rate. So if you have a reaction you don't want to
take place (like elements degrading) that rule of thumb would say it
could happen nearly 8 times faster at cone 8 than cone 6--64 times
faster at cone 10. Now rules of thumb are just "guestimates" and pretty
obviously aren't accurate in this situation--but certainly those
"small" temperature differences can make a huge difference depending on
exactly what is happening. Percentage differences in temperature is not
the best way to look at this issue.
Regards,
John
On Apr 9, 2005, at 4:05 PM, URL Krueger wrote:
> Cone 6 = 1220 C (at 60 C / hour)
> Cone 8 = 1247 C +27C +2%
> Cone 10 = 1282 C +62C +5%
> Cone 12 = 1304 C +84C +7%
>
> Isn't it interesting that so much debate occurs over such a
> small temperature difference.
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
UU KRC on tue 12 apr 05
--- Earl Brunner wrote:
> I agree Wes, I have seen glazes where 30 degrees
> made a huge difference and
> that is amazing when you think that 30 degrees is
> maybe 1.5% of the total
> firing temperature at cone 6. Further more, I bet
> some of the glaze guru
> types would tell us that "visible" difference isn't
> the same thing as
> "stable" at that wide of a range either.
>
> Earl Brunner
> Las Vegas, NV
>
A short side note about the % difference between one
temp. and another. 100 degrees F is not actually twice
as hot as 50 degrees F. I believe you have to compare
the temperatures using a scale based around absolute
zero to even attempt to do a ratio comparison of
temperatures. Another thought and one that I think
many people realize, without feeling the need to say
it, is that 5 degrees difference does make a
difference. The best way I can explain this is that
water won't boil if it only gets to 207 degrees F.
(assuming atmospheric pressure at sea level, and all
that)
Jared
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Elizabeth Priddy on tue 12 apr 05
Just think about raku. If you have seen it done without pyrometers,
you look inside and wait for the glaze to "melt" and then you pull it.
One minute it is not ready and bubbling on the surface and literally the next minute,
you need to pull it. So one minute worth of extra heat can make that kind of difference.
UU KRC wrote:
--- Earl Brunner
wrote:
> I agree Wes, I have seen glazes where 30 degrees
> made a huge difference and
> that is amazing when you think that 30 degrees is
> maybe 1.5% of the total
> firing temperature at cone 6. Further more, I bet
> some of the glaze guru
> types would tell us that "visible" difference isn't
> the same thing as
> "stable" at that wide of a range either.
>
> Earl Brunner
> Las Vegas, NV
>
A short side note about the % difference between one
temp. and another. 100 degrees F is not actually twice
as hot as 50 degrees F. I believe you have to compare
the temperatures using a scale based around absolute
zero to even attempt to do a ratio comparison of
temperatures. Another thought and one that I think
many people realize, without feeling the need to say
it, is that 5 degrees difference does make a
difference. The best way I can explain this is that
water won't boil if it only gets to 207 degrees F.
(assuming atmospheric pressure at sea level, and all
that)
Jared
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Elizabeth Priddy
252-504-2622
1273 Hwy 101
Beaufort, NC 28516
http://www.elizabethpriddy.com
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Earl Brunner on tue 12 apr 05
I know, it's just that in this big wide universe we live in, there is this
HUGE spread in temperatures and I am just continually amazed that the range
we live in is really such a narrow part of that spread.....
Earl Brunner
Las Vegas, NV
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of UU KRC
Sent: Tuesday, April 12, 2005 4:28 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: cone 10 electric-all kilns equal?
--- Earl Brunner wrote:
> I agree Wes, I have seen glazes where 30 degrees
> made a huge difference and
> that is amazing when you think that 30 degrees is
> maybe 1.5% of the total
> firing temperature at cone 6. Further more, I bet
> some of the glaze guru
> types would tell us that "visible" difference isn't
> the same thing as
> "stable" at that wide of a range either.
>
> Earl Brunner
> Las Vegas, NV
>
A short side note about the % difference between one
temp. and another. 100 degrees F is not actually twice
as hot as 50 degrees F. I believe you have to compare
the temperatures using a scale based around absolute
zero to even attempt to do a ratio comparison of
temperatures. Another thought and one that I think
many people realize, without feeling the need to say
it, is that 5 degrees difference does make a
difference. The best way I can explain this is that
water won't boil if it only gets to 207 degrees F.
(assuming atmospheric pressure at sea level, and all
that)
Jared
__________________________________
Do you Yahoo!?
Make Yahoo! your home page
http://www.yahoo.com/r/hs
____________________________________________________________________________
__
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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