Malone & Dean McRaine on fri 14 apr 00
Aloha all: I've been firing ^10 oxidation for many years first in an
electric and now in a 20 c.f. gas kiln. Just in case your brain hasn't had
to work today consider this: One thing that I didn't learn for years until
I took the trouble to calculate the span of degrees between cones is that
not all cones are created equal. We tend to think that the temp difference
between cones is all the same, or I did, but 'taint so. Hence (according
to Chappell in the Potter's Complete Book of Clay and Glazes) ^5-^6=44F,
^6-^7=38F, ^7-^8=17F, ^8-^9=45F, ^9-^10=36F, ^10-^11=36F. To further
confuse the issue of what temp a cone is trying to tell you, try putting
two sources side by side, for instance, Chappell and Hamer. These are two
well respected sources of info, but they can't seem to agree on what temp
causes cones to fall over. Hamer lists two heating rates, since faster
heating causes cones to fall at a higher temp. Even so a comparison looks
like this:
Chappell Hamer; 108f/hr 270F/hr
^5 2201 2151 2185
^6 2245 2194 2232
^7 2283 2219 2264
^8 2300 2257 2305
^9 2345 2300 2336
^10 2381 2345 2381
^11 2417 2361 2399
Try calculating the temp difference between cones in each column for your
favorite range..
This all very confusing if you're being scientific but the most interesting
thing is that some cones are very close temp-wise and others are farther
apart.
the difference between ^10 and ^11 is only 16F or 18F in Hamer's figures.
^7-^8 is only 17F in Chappell's. They, of course don't agree each other.
Any ClayArters understand these discrepancies??
But i digress..the little cones seem to fall when they're supposed to. The
questions on the table are more practical. I like ^ 10 for the range of
fluxes available. At ^6 choices of fluxes seem limited to me hence the
range of color (though brighter) and texture is less than at ^8-10. I've
developed some nice bright colors that resonate well with the brilliant
light of Hawaii. When I fired in my electric kiln I added a layer of fiber
insulation to up the firing range to ^10. This also slowed my cooling cycle
which helps glaze development. I've had very long element life and I don't
think this should be a worry. I sprayed ITC on the kiln walls and elements
and it only made a small improvement in my firings, durability was a big
plus, though. I don't suggest spraying the elements, if you ever have to
take one out you'll destroy the grooves in your bricks trying to get those
ITC-coated elements to squeeze through. If it's more insulaton you're
after, which is a good idea if you've got a regular 2 1/2" thick hobby
kiln, better to take off the stainless jacket of the kiln and wrap it with
1" fiber and replace the jacket. I also added fiber to the top and bottom.
I think that ^8-10 oxidation is an underexplored territory. We carry over
many ideas from the days of Bernard Leach who idealized ^10 reduction.
^8-10 Ox is a great range to work in with many unique colors and easier to
get consistent results than reduction. Reduction tends to mute clay and
many glazes while they tend to be brighter in oxidation. I haven't noticed
a great difference between electric and gas firing but this may be because
I always do a 1-2 hour soak to give my glazes plenty of time to melt.
Good Luck
Dean
http://www.kauaifoods.com/clients/shop_lightwave.html
Hank Murrow on sun 16 apr 00
>----------------------------Original message----------------------------
Snip... One thing that I didn't learn for years until
>I took the trouble to calculate the span of degrees between cones is that
>not all cones are created equal. We tend to think that the temp difference
>between cones is all the same, or I did, but 'taint so.
>Any ClayArters understand these discrepancies??
Dear Dean; Cones are based upon mole ratios. The mole formula for C/10 is
.3 K2O, .7 CaO, 1.0 Al2O3, and 10.0 SiO2. The mole formula for C/9 is the
same except .9 Al203 & 9.0 Si02; and so on down to C/3, where the Al & Si
change more slowly. These formulas can be found in David
Green's,"Understanding Pottery Glazes". Eutectics often change in sharp
jumps, hence the discontinuity of temperature difference between
neighboring cones. Blame it on the moles. Of course, in fairness to the
genius of Mr.Seger, our glazes (being composed of moles) are doing the same
things in the kiln, and that's why the cones are so useful. Hank in Eugene
Frederich, Tim on wed 19 apr 00
Hello,
I wanted to respond to Dean's inquiry about cones. There has always
been a difference in temperature between the different cones. The
combination of the materials and the different melting points do not allow
for an exact spacing between each cone. Different heating rates cause
different equivalent end point temperatures since cones deform based on a
time and temperature relationship called heatwork. You cannot compare
temperatures from different heating rates for the same cone number. I
noticed that the temperatures listed in the Hamer book are not completely
accurate compared to the chart that Orton publishes today. You can go to
www.ortonceramic.com to find the most recent cone chart and download a copy
to use. Our current chart is dated 1996. The equivalent temperatures listed
have changed slightly over the years as our ability through better
technology has enabled us to measure temperatures more accurately. If you
have further questions please contact me.
Sincerely,
Tim Frederich, Orton Ceramic Foundation
> ----------
> From: Malone & Dean McRaine[SMTP:beezer@aloha.net]
> Sent: Friday, April 14, 2000 10:33 PM
> To: CLAYART@LSV.UKY.EDU
> Subject: ^6 vs ^9 (or 10) oxidation and other cone arcanities
>
> ----------------------------Original message----------------------------
> Aloha all: I've been firing ^10 oxidation for many years first in an
> electric and now in a 20 c.f. gas kiln. Just in case your brain hasn't
> had
> to work today consider this: One thing that I didn't learn for years
> until
> I took the trouble to calculate the span of degrees between cones is that
> not all cones are created equal. We tend to think that the temp
> difference
> between cones is all the same, or I did, but 'taint so. Hence (according
> to Chappell in the Potter's Complete Book of Clay and Glazes) ^5-^6=44F,
> ^6-^7=38F, ^7-^8=17F, ^8-^9=45F, ^9-^10=36F, ^10-^11=36F. To further
> confuse the issue of what temp a cone is trying to tell you, try putting
> two sources side by side, for instance, Chappell and Hamer. These are two
> well respected sources of info, but they can't seem to agree on what temp
> causes cones to fall over. Hamer lists two heating rates, since faster
> heating causes cones to fall at a higher temp. Even so a comparison looks
> like this:
> Chappell Hamer; 108f/hr 270F/hr
> ^5 2201 2151 2185
> ^6 2245 2194 2232
> ^7 2283 2219 2264
> ^8 2300 2257 2305
> ^9 2345 2300 2336
> ^10 2381 2345 2381
> ^11 2417 2361 2399
>
> Try calculating the temp difference between cones in each column for your
> favorite range..
>
> This all very confusing if you're being scientific but the most
> interesting
> thing is that some cones are very close temp-wise and others are farther
> apart.
> the difference between ^10 and ^11 is only 16F or 18F in Hamer's figures.
> ^7-^8 is only 17F in Chappell's. They, of course don't agree each other.
> Any ClayArters understand these discrepancies??
>
> But i digress..the little cones seem to fall when they're supposed to. The
> questions on the table are more practical. I like ^ 10 for the range of
> fluxes available. At ^6 choices of fluxes seem limited to me hence the
> range of color (though brighter) and texture is less than at ^8-10. I've
> developed some nice bright colors that resonate well with the brilliant
> light of Hawaii. When I fired in my electric kiln I added a layer of
> fiber
> insulation to up the firing range to ^10. This also slowed my cooling
> cycle
> which helps glaze development. I've had very long element life and I
> don't
> think this should be a worry. I sprayed ITC on the kiln walls and elements
> and it only made a small improvement in my firings, durability was a big
> plus, though. I don't suggest spraying the elements, if you ever have to
> take one out you'll destroy the grooves in your bricks trying to get those
> ITC-coated elements to squeeze through. If it's more insulaton you're
> after, which is a good idea if you've got a regular 2 1/2" thick hobby
> kiln, better to take off the stainless jacket of the kiln and wrap it with
> 1" fiber and replace the jacket. I also added fiber to the top and bottom.
> I think that ^8-10 oxidation is an underexplored territory. We carry over
> many ideas from the days of Bernard Leach who idealized ^10 reduction.
> ^8-10 Ox is a great range to work in with many unique colors and easier to
> get consistent results than reduction. Reduction tends to mute clay and
> many glazes while they tend to be brighter in oxidation. I haven't
> noticed
> a great difference between electric and gas firing but this may be because
> I always do a 1-2 hour soak to give my glazes plenty of time to melt.
> Good Luck
> Dean
>
>
> http://www.kauaifoods.com/clients/shop_lightwave.html
>
Geoff Walker on thu 20 apr 00
Hello Tim,
I don't know whether they are still available, but I remember back in my
first 10 years or so of potting that Harrison-Meyer made cones which
were supposed to bend at 20 degree (Celsius) intervals. Whatever
happened to them? It was so easy then to work out a temperature when
given a cone number. Now I have to constantly look up the charts. Such a
pain.
Geoff.
Frederich, Tim wrote:
> ----------------------------Original
> message----------------------------
> Hello,
> I wanted to respond to Dean's inquiry about cones. There has
> always
> been a difference in temperature between the different cones. The
> combination of the materials and the different melting points do not
> allow
> for an exact spacing between each cone. Different heating rates cause
> different equivalent end point temperatures since cones deform based
> on a
> time and temperature relationship called heatwork. You cannot compare
> temperatures from different heating rates for the same cone number. I
> noticed that the temperatures listed in the Hamer book are not
> completely
> accurate compared to the chart that Orton publishes today. You can go
> to
> www.ortonceramic.com to find the most recent cone chart and download a
> copy
> to use. Our current chart is dated 1996. The equivalent temperatures
> listed
> have changed slightly over the years as our ability through better
> technology has enabled us to measure temperatures more accurately. If
> you
> have further questions please contact me.
>
> Sincerely,
> Tim Frederich, Orton Ceramic Foundation
>
> > ----------
> > From: Malone & Dean McRaine[SMTP:beezer@aloha.net]
> > Sent: Friday, April 14, 2000 10:33 PM
> > To: CLAYART@LSV.UKY.EDU
> > Subject: ^6 vs ^9 (or 10) oxidation and other cone arcanities
> >
> > ----------------------------Original
> message----------------------------
> > Aloha all: I've been firing ^10 oxidation for many years first in
> an
> > electric and now in a 20 c.f. gas kiln. Just in case your brain
> hasn't
> > had
> > to work today consider this: One thing that I didn't learn for
> years
> > until
> > I took the trouble to calculate the span of degrees between cones is
> that
> > not all cones are created equal. We tend to think that the temp
> > difference
> > between cones is all the same, or I did, but 'taint so. Hence
> (according
> > to Chappell in the Potter's Complete Book of Clay and Glazes)
> ^5-^6=44F,
> > ^6-^7=38F, ^7-^8=17F, ^8-^9=45F, ^9-^10=36F, ^10-^11=36F. To further
>
> > confuse the issue of what temp a cone is trying to tell you, try
> putting
> > two sources side by side, for instance, Chappell and Hamer. These
> are two
> > well respected sources of info, but they can't seem to agree on what
> temp
> > causes cones to fall over. Hamer lists two heating rates, since
> faster
> > heating causes cones to fall at a higher temp. Even so a comparison
> looks
> > like this:
> > Chappell Hamer; 108f/hr 270F/hr
> > ^5 2201 2151 2185
> > ^6 2245 2194 2232
> > ^7 2283 2219 2264
> > ^8 2300 2257 2305
> > ^9 2345 2300 2336
> > ^10 2381 2345 2381
> > ^11 2417 2361 2399
> >
> > Try calculating the temp difference between cones in each column for
> your
> > favorite range..
> >
> > This all very confusing if you're being scientific but the most
> > interesting
> > thing is that some cones are very close temp-wise and others are
> farther
> > apart.
> > the difference between ^10 and ^11 is only 16F or 18F in Hamer's
> figures.
> > ^7-^8 is only 17F in Chappell's. They, of course don't agree each
> other.
> > Any ClayArters understand these discrepancies??
> >
> > But i digress..the little cones seem to fall when they're supposed
> to. The
> > questions on the table are more practical. I like ^ 10 for the
> range of
> > fluxes available. At ^6 choices of fluxes seem limited to me hence
> the
> > range of color (though brighter) and texture is less than at ^8-10.
> I've
> > developed some nice bright colors that resonate well with the
> brilliant
> > light of Hawaii. When I fired in my electric kiln I added a layer
> of
> > fiber
> > insulation to up the firing range to ^10. This also slowed my
> cooling
> > cycle
> > which helps glaze development. I've had very long element life and
> I
> > don't
> > think this should be a worry. I sprayed ITC on the kiln walls and
> elements
> > and it only made a small improvement in my firings, durability was a
> big
> > plus, though. I don't suggest spraying the elements, if you ever
> have to
> > take one out you'll destroy the grooves in your bricks trying to get
> those
> > ITC-coated elements to squeeze through. If it's more insulaton
> you're
> > after, which is a good idea if you've got a regular 2 1/2" thick
> hobby
> > kiln, better to take off the stainless jacket of the kiln and wrap
> it with
> > 1" fiber and replace the jacket. I also added fiber to the top and
> bottom.
> > I think that ^8-10 oxidation is an underexplored territory. We
> carry over
> > many ideas from the days of Bernard Leach who idealized ^10
> reduction.
> > ^8-10 Ox is a great range to work in with many unique colors and
> easier to
> > get consistent results than reduction. Reduction tends to mute clay
> and
> > many glazes while they tend to be brighter in oxidation. I haven't
> > noticed
> > a great difference between electric and gas firing but this may be
> because
> > I always do a 1-2 hour soak to give my glazes plenty of time to
> melt.
> > Good Luck
> > Dean
> >
> >
> > http://www.kauaifoods.com/clients/shop_lightwave.html
> >
Frederich, Tim on fri 21 apr 00
Hi Geoff,
I think Harrison cones are still available and produced in England.
I think that the company has changed hands several times. They do not make
as many cone numbers as Orton does or as many types of cones. If you look at
the tables in the back of Frank and Janet Hamer's wonderful book, The
Potter's Dictionary, you will see that their temperatures vary differently
between cone numbers. Orton cones are registered with the National Bureau of
Standards and maintain that same accuracy from batch to batch. We also have
the patented Self Supporting Cone. I keep a chart next to the kilns to refer
to if I forget a temperature. Please contact me if you need further
information.
Tim Frederich, Orton Ceramic Foundation
> ----------
> From: Geoff Walker[SMTP:gwalker@fan.net.au]
> Sent: Thursday, April 20, 2000 3:47 PM
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: ^6 vs ^9 (or 10) oxidation and other cone arcanities
>
> ----------------------------Original message----------------------------
> Hello Tim,
>
> I don't know whether they are still available, but I remember back in my
> first 10 years or so of potting that Harrison-Meyer made cones which
> were supposed to bend at 20 degree (Celsius) intervals. Whatever
> happened to them? It was so easy then to work out a temperature when
> given a cone number. Now I have to constantly look up the charts. Such a
> pain.
>
> Geoff.
>
> Frederich, Tim wrote:
>
> > ----------------------------Original
> > message----------------------------
> > Hello,
> > I wanted to respond to Dean's inquiry about cones. There has
> > always
> > been a difference in temperature between the different cones. The
> > combination of the materials and the different melting points do not
> > allow
> > for an exact spacing between each cone. Different heating rates cause
> > different equivalent end point temperatures since cones deform based
> > on a
> > time and temperature relationship called heatwork. You cannot compare
> > temperatures from different heating rates for the same cone number. I
> > noticed that the temperatures listed in the Hamer book are not
> > completely
> > accurate compared to the chart that Orton publishes today. You can go
> > to
> > www.ortonceramic.com to find the most recent cone chart and download a
> > copy
> > to use. Our current chart is dated 1996. The equivalent temperatures
> > listed
> > have changed slightly over the years as our ability through better
> > technology has enabled us to measure temperatures more accurately. If
> > you
> > have further questions please contact me.
> >
> > Sincerely,
> > Tim Frederich, Orton Ceramic Foundation
> >
> > > ----------
> > > From: Malone & Dean McRaine[SMTP:beezer@aloha.net]
> > > Sent: Friday, April 14, 2000 10:33 PM
> > > To: CLAYART@LSV.UKY.EDU
> > > Subject: ^6 vs ^9 (or 10) oxidation and other cone arcanities
> > >
> > > ----------------------------Original
> > message----------------------------
> > > Aloha all: I've been firing ^10 oxidation for many years first in
> > an
> > > electric and now in a 20 c.f. gas kiln. Just in case your brain
> > hasn't
> > > had
> > > to work today consider this: One thing that I didn't learn for
> > years
> > > until
> > > I took the trouble to calculate the span of degrees between cones is
> > that
> > > not all cones are created equal. We tend to think that the temp
> > > difference
> > > between cones is all the same, or I did, but 'taint so. Hence
> > (according
> > > to Chappell in the Potter's Complete Book of Clay and Glazes)
> > ^5-^6=44F,
> > > ^6-^7=38F, ^7-^8=17F, ^8-^9=45F, ^9-^10=36F, ^10-^11=36F. To further
> >
> > > confuse the issue of what temp a cone is trying to tell you, try
> > putting
> > > two sources side by side, for instance, Chappell and Hamer. These
> > are two
> > > well respected sources of info, but they can't seem to agree on what
> > temp
> > > causes cones to fall over. Hamer lists two heating rates, since
> > faster
> > > heating causes cones to fall at a higher temp. Even so a comparison
> > looks
> > > like this:
> > > Chappell Hamer; 108f/hr 270F/hr
> > > ^5 2201 2151 2185
> > > ^6 2245 2194 2232
> > > ^7 2283 2219 2264
> > > ^8 2300 2257 2305
> > > ^9 2345 2300 2336
> > > ^10 2381 2345 2381
> > > ^11 2417 2361 2399
> > >
> > > Try calculating the temp difference between cones in each column for
> > your
> > > favorite range..
> > >
> > > This all very confusing if you're being scientific but the most
> > > interesting
> > > thing is that some cones are very close temp-wise and others are
> > farther
> > > apart.
> > > the difference between ^10 and ^11 is only 16F or 18F in Hamer's
> > figures.
> > > ^7-^8 is only 17F in Chappell's. They, of course don't agree each
> > other.
> > > Any ClayArters understand these discrepancies??
> > >
> > > But i digress..the little cones seem to fall when they're supposed
> > to. The
> > > questions on the table are more practical. I like ^ 10 for the
> > range of
> > > fluxes available. At ^6 choices of fluxes seem limited to me hence
> > the
> > > range of color (though brighter) and texture is less than at ^8-10.
> > I've
> > > developed some nice bright colors that resonate well with the
> > brilliant
> > > light of Hawaii. When I fired in my electric kiln I added a layer
> > of
> > > fiber
> > > insulation to up the firing range to ^10. This also slowed my
> > cooling
> > > cycle
> > > which helps glaze development. I've had very long element life and
> > I
> > > don't
> > > think this should be a worry. I sprayed ITC on the kiln walls and
> > elements
> > > and it only made a small improvement in my firings, durability was a
> > big
> > > plus, though. I don't suggest spraying the elements, if you ever
> > have to
> > > take one out you'll destroy the grooves in your bricks trying to get
> > those
> > > ITC-coated elements to squeeze through. If it's more insulaton
> > you're
> > > after, which is a good idea if you've got a regular 2 1/2" thick
> > hobby
> > > kiln, better to take off the stainless jacket of the kiln and wrap
> > it with
> > > 1" fiber and replace the jacket. I also added fiber to the top and
> > bottom.
> > > I think that ^8-10 oxidation is an underexplored territory. We
> > carry over
> > > many ideas from the days of Bernard Leach who idealized ^10
> > reduction.
> > > ^8-10 Ox is a great range to work in with many unique colors and
> > easier to
> > > get consistent results than reduction. Reduction tends to mute clay
> > and
> > > many glazes while they tend to be brighter in oxidation. I haven't
> > > noticed
> > > a great difference between electric and gas firing but this may be
> > because
> > > I always do a 1-2 hour soak to give my glazes plenty of time to
> > melt.
> > > Good Luck
> > > Dean
> > >
> > >
> > > http://www.kauaifoods.com/clients/shop_lightwave.html
> > >
>
Stephen Mills on sat 22 apr 00
Harrison cones were made in co-operation with Bell Research in America,
and known in the UK as Harrison Bell. With the amalgamation of Harrison
Meyer, Wengers, and Podmores into Potterycrafts, HB cones stayed around
for a while but are fading from the scene. Their chief benefit to UK
potters was that they filled the temperature gap between 1060oC (cone
04) and 1101oC (cone 03). As many UK earthenware potters fire at 1080oC
this was/is a blessing.
Harrison Mini Bars for use in the ubiquitous Kiln Sitter are still
readily available in the UK.
I haven't tried this, but perhaps typing Bell Research into your Browser
and trying to contact them that way might work.
Steve Mills
Bath
UK
>
>> ----------
>> From: Geoff Walker[SMTP:gwalker@fan.net.au]
>> Sent: Thursday, April 20, 2000 3:47 PM
>> To: CLAYART@LSV.UKY.EDU
>> Subject: Re: ^6 vs ^9 (or 10) oxidation and other cone arcanities
>>
>> ----------------------------Original message----------------------------
>> Hello Tim,
>>
>> I don't know whether they are still available, but I remember back in my
>> first 10 years or so of potting that Harrison-Meyer made cones which
>> were supposed to bend at 20 degree (Celsius) intervals. Whatever
>> happened to them? It was so easy then to work out a temperature when
>> given a cone number. Now I have to constantly look up the charts. Such a
>> pain.
>>
>> Geoff.
>>
>> Frederich, Tim wrote:
>>
>> > ----------------------------Original
>> > message----------------------------
>> > Hello,
>> > I wanted to respond to Dean's inquiry about cones. There has
>> > always
>> > been a difference in temperature between the different cones. The
>> > combination of the materials and the different melting points do not
>> > allow
>> > for an exact spacing between each cone. Different heating rates cause
>> > different equivalent end point temperatures since cones deform based
>> > on a
>> > time and temperature relationship called heatwork. You cannot compare
>> > temperatures from different heating rates for the same cone number. I
>> > noticed that the temperatures listed in the Hamer book are not
>> > completely
>> > accurate compared to the chart that Orton publishes today. You can go
>> > to
>> > www.ortonceramic.com to find the most recent cone chart and download a
>> > copy
>> > to use. Our current chart is dated 1996. The equivalent temperatures
>> > listed
>> > have changed slightly over the years as our ability through better
>> > technology has enabled us to measure temperatures more accurately. If
>> > you
>> > have further questions please contact me.
>> >
>> > Sincerely,
>> > Tim Frederich, Orton Ceramic Foundation
>> >
>> > > ----------
>> > > From: Malone & Dean McRaine[SMTP:beezer@aloha.net]
>> > > Sent: Friday, April 14, 2000 10:33 PM
>> > > To: CLAYART@LSV.UKY.EDU
>> > > Subject: ^6 vs ^9 (or 10) oxidation and other cone arcanities
>> > >
>> > > ----------------------------Original
>> > message----------------------------
>> > > Aloha all: I've been firing ^10 oxidation for many years first in
>> > an
>> > > electric and now in a 20 c.f. gas kiln. Just in case your brain
>> > hasn't
>> > > had
>> > > to work today consider this: One thing that I didn't learn for
>> > years
>> > > until
>> > > I took the trouble to calculate the span of degrees between cones is
>> > that
>> > > not all cones are created equal. We tend to think that the temp
>> > > difference
>> > > between cones is all the same, or I did, but 'taint so. Hence
>> > (according
>> > > to Chappell in the Potter's Complete Book of Clay and Glazes)
>> > ^5-^6=44F,
>> > > ^6-^7=38F, ^7-^8=17F, ^8-^9=45F, ^9-^10=36F, ^10-^11=36F. To further
>> >
>> > > confuse the issue of what temp a cone is trying to tell you, try
>> > putting
>> > > two sources side by side, for instance, Chappell and Hamer. These
>> > are two
>> > > well respected sources of info, but they can't seem to agree on what
>> > temp
>> > > causes cones to fall over. Hamer lists two heating rates, since
>> > faster
>> > > heating causes cones to fall at a higher temp. Even so a comparison
>> > looks
>> > > like this:
>> > > Chappell Hamer; 108f/hr 270F/hr
>> > > ^5 2201 2151 2185
>> > > ^6 2245 2194 2232
>> > > ^7 2283 2219 2264
>> > > ^8 2300 2257 2305
>> > > ^9 2345 2300 2336
>> > > ^10 2381 2345 2381
>> > > ^11 2417 2361 2399
>> > >
>> > > Try calculating the temp difference between cones in each column for
>> > your
>> > > favorite range..
>> > >
>> > > This all very confusing if you're being scientific but the most
>> > > interesting
>> > > thing is that some cones are very close temp-wise and others are
>> > farther
>> > > apart.
>> > > the difference between ^10 and ^11 is only 16F or 18F in Hamer's
>> > figures.
>> > > ^7-^8 is only 17F in Chappell's. They, of course don't agree each
>> > other.
>> > > Any ClayArters understand these discrepancies??
>> > >
>> > > But i digress..the little cones seem to fall when they're supposed
>> > to. The
>> > > questions on the table are more practical. I like ^ 10 for the
>> > range of
>> > > fluxes available. At ^6 choices of fluxes seem limited to me hence
>> > the
>> > > range of color (though brighter) and texture is less than at ^8-10.
>> > I've
>> > > developed some nice bright colors that resonate well with the
>> > brilliant
>> > > light of Hawaii. When I fired in my electric kiln I added a layer
>> > of
>> > > fiber
>> > > insulation to up the firing range to ^10. This also slowed my
>> > cooling
>> > > cycle
>> > > which helps glaze development. I've had very long element life and
>> > I
>> > > don't
>> > > think this should be a worry. I sprayed ITC on the kiln walls and
>> > elements
>> > > and it only made a small improvement in my firings, durability was a
>> > big
>> > > plus, though. I don't suggest spraying the elements, if you ever
>> > have to
>> > > take one out you'll destroy the grooves in your bricks trying to get
>> > those
>> > > ITC-coated elements to squeeze through. If it's more insulaton
>> > you're
>> > > after, which is a good idea if you've got a regular 2 1/2" thick
>> > hobby
>> > > kiln, better to take off the stainless jacket of the kiln and wrap
>> > it with
>> > > 1" fiber and replace the jacket. I also added fiber to the top and
>> > bottom.
>> > > I think that ^8-10 oxidation is an underexplored territory. We
>> > carry over
>> > > many ideas from the days of Bernard Leach who idealized ^10
>> > reduction.
>> > > ^8-10 Ox is a great range to work in with many unique colors and
>> > easier to
>> > > get consistent results than reduction. Reduction tends to mute clay
>> > and
>> > > many glazes while they tend to be brighter in oxidation. I haven't
>> > > noticed
>> > > a great difference between electric and gas firing but this may be
>> > because
>> > > I always do a 1-2 hour soak to give my glazes plenty of time to
>> > melt.
>> > > Good Luck
>> > > Dean
>> > >
>> > >
>> > > http://www.kauaifoods.com/clients/shop_lightwave.html
>> > >
>>
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Tel: **44 (0)1225 311699
Fax: **44 (0)870 0526466
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