Tom Wirt on wed 1 mar 00
OK. We just fired our first load of fully reduced work...reduction (.7 on
the probe) starting at cone 010 and continuing out to finish cone 10. We
did not go into neutral after body reduction...just stayed at point 7.
Our normal pattern is to fire neutral to light oxidation until about 2000
degF. and then go to moderate reduction for the finish.
The temmokus smoothed out and were fabulous. The temmoku usually has a
slight orange peel surface...this time it looked like one of Ron Roy's. The
reds achieved and held red beautifully. Less crazing on some of the shinos.
All the glazes were smoother and pinholing, even on our pesky Rutile blue
(altered moonlight) was minimized. (It did change the color of the blue
somewhat). So what gives?
The temperature rise is the same, the final temp is the same, the total
firing time is the same. The only difference is the earlier reduction. I'm
seeking to understand the mechanics/physics of why that extra reduction (I
assume applied during the sintering or early melt stages) should cause such
a dramatic surface improvement.
Tom Wirt
June Perry on thu 2 mar 00
This is an old standby, nice black. I don't think the low barium would be a
problem, but you could substitute 75% of the barium with strontium carb if
that's a concern.
#10 SECREST BLACK CONE 9 REDUCTION BLACK SEMI GLOSS
CUSTER FELDSPAR 54
WHITING 13
BARIUM CARBONATE 2.5
ZINC OXIDE 2.5
FLINT 22
EDGAR PLASTIC KAOLIN 6
RED IRON OXIDE 8%
Regards,
June
Cantello Studios on thu 2 mar 00
Sounds like you had a great reduction firing. So what's your? well most good
reduction glazes like a long slow
firing with 6 to 7 Hr. of reduction. My firing will go 11 to 12 Hr.to cone
11 most all the time. With this
type of reduction I am surprise and pleased to hear that your rutile blue
made it through. Point being that every
time I try to fire a rutile glaze of 4 to 8 percent in this type of
reduction it pinholes big time.(?)would you
like to share your rutile blue put it out there or send it to
tleecan@2xtreme.net :)
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
Of Tom Wirt
Sent: Wednesday, March 01, 2000 9:46 AM
To: CLAYART@LSV.UKY.EDU
Subject: Oxidation vs Reduction
----------------------------Original message----------------------------
OK. We just fired our first load of fully reduced work...reduction (.7 on
the probe) starting at cone 010 and continuing out to finish cone 10. We
did not go into neutral after body reduction...just stayed at point 7.
Our normal pattern is to fire neutral to light oxidation until about 2000
degF. and then go to moderate reduction for the finish.
The temmokus smoothed out and were fabulous. The temmoku usually has a
slight orange peel surface...this time it looked like one of Ron Roy's. The
reds achieved and held red beautifully. Less crazing on some of the shinos.
All the glazes were smoother and pinholing, even on our pesky Rutile blue
(altered moonlight) was minimized. (It did change the color of the blue
somewhat). So what gives?
The temperature rise is the same, the final temp is the same, the total
firing time is the same. The only difference is the earlier reduction. I'm
seeking to understand the mechanics/physics of why that extra reduction (I
assume applied during the sintering or early melt stages) should cause such
a dramatic surface improvement.
Tom Wirt
Hank Murrow on fri 3 mar 00
>----------------------------Original message----------------------------
>OK. We just fired our first load of fully reduced work...reduction (.7 on
>the probe) starting at cone 010 and continuing out to finish cone 10. We
>did not go into neutral after body reduction...just stayed at point 7.
>
>Our normal pattern is to fire neutral to light oxidation until about 2000
>degF. and then go to moderate reduction for the finish.
>
>The temmokus smoothed out and were fabulous. The temmoku usually has a
>slight orange peel surface...this time it looked like one of Ron Roy's. The
>reds achieved and held red beautifully. Less crazing on some of the shinos.
>All the glazes were smoother and pinholing, even on our pesky Rutile blue
>(altered moonlight) was minimized. (It did change the color of the blue
>somewhat). So what gives?
>
>The temperature rise is the same, the final temp is the same, the total
>firing time is the same. The only difference is the earlier reduction. I'm
>seeking to understand the mechanics/physics of why that extra reduction (I
>assume applied during the sintering or early melt stages) should cause such
>a dramatic surface improvement.
>
>Tom Wirt
Dear Tom; The reduction changes the Fe2O3 to FeO, which is a flux; thus
fostering a more complete melt. If you want to try something interesting,
let the kiln cool normally down to C/1+ and start it up again in Oxidation
with enough gas supply to hold the temperature steady(need a pyrometer for
this) for 3 or 4 hours. Then turn off and cool normally. I predict lots of
iron reds and khakis and dynamite Shinos, and No pinholes. Hank in Eugene
David McDonald on fri 3 mar 00
Tom,
I can understand your curiousity at why glazes would come out so much
smoother, and why you would see such a dramatic improvement in the
surfaces after a firing which was MORE reduced from body reduction temp
all the way to the end. I have noticed that at times too, and have always
wondered. Haven't we been told that the more oxidized and "cleaner" the
firing the less problems we could expect with glaze surfaces? And yet at
times when I have fired (reduction, cone 10) with the reduction stages
shortened, and a longer neutral or oxidizing period, I've frequently
noticed glaze defects increase. Pinholes, orange peel like, or not so
smooth surfaces. So what you've described below I can concur as my own
experiences and results too. Very odd. I guess I still don't know
enough!
I'm guessing that the change in color of the rutile blue glazes is due
to some carbon entrapment, at least that's what is happening for me when
I notice rutile blue glazes darkened from their normal brilliancy. Not a
desireable effect in that case. David
> ----------------------------Original
> message----------------------------
> OK. We just fired our first load of fully reduced work...reduction
> (.7 on
> the probe) starting at cone 010 and continuing out to finish cone
> 10. We
> did not go into neutral after body reduction...just stayed at point
> 7.
>
> Our normal pattern is to fire neutral to light oxidation until about
> 2000
> degF. and then go to moderate reduction for the finish.
>
> The temmokus smoothed out and were fabulous. The temmoku usually
> has a
> slight orange peel surface...this time it looked like one of Ron
> Roy's. The
> reds achieved and held red beautifully. Less crazing on some of the
> shinos.
> All the glazes were smoother and pinholing, even on our pesky Rutile
> blue
> (altered moonlight) was minimized. (It did change the color of the
> blue
> somewhat). So what gives?
>
> The temperature rise is the same, the final temp is the same, the
> total
> firing time is the same. The only difference is the earlier
> reduction. I'm
> seeking to understand the mechanics/physics of why that extra
> reduction (I
> assume applied during the sintering or early melt stages) should
> cause such
> a dramatic surface improvement.
>
> Tom Wirt
David McDonald
Limberlost Pottery
721 First Street
Prescott,AZ 86301
(520)778-7854 claydog@juno.com
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tgschs10 on sat 4 mar 00
Tom,
I'm new at the reduction firing also but I've read Nils Lou's book Art of
Firing and talked with several "experts" I have been told that body
reduction occurs beginning about 1650 F and lasts thru about 1850 F. If your
not reducing earlier than 2000 C you might be missing your body reduction.
My reading is that reduction is important two times; once for body reduction
and secondly for glaze reduction which begins at about 2010 F. Nils
indicates he starts reduction about 1650 F and maintains 0.63-0.65 on the
oxyprobe from 2010 F; for the body reduction he keeps the oxyprobe between
0.45-0.56. Having fired my kiln with Nils in the past 2 months and twice
since by myself, I can assert that I've followed this procedure with really
great results. I am also told that if you reduce too early you can get
carbonization of your body and actually cause structural weakness. I'm
interested in Hank's recommendation and since I have a dual gas/electric I
plan to turn on the electric as he recommends and hold the temperature
recommended for 3 hours.
Best
Tom Sawyer
Orlando, Fl
tgschs10@msn.com
----- Original Message -----
From: "Hank Murrow"
To:
Sent: Friday, March 03, 2000 9:38 AM
Subject: Re: Oxidation vs Reduction
> ----------------------------Original message----------------------------
> >----------------------------Original message----------------------------
> >OK. We just fired our first load of fully reduced work...reduction (.7
on
> >the probe) starting at cone 010 and continuing out to finish cone 10. We
> >did not go into neutral after body reduction...just stayed at point 7.
> >
> >Our normal pattern is to fire neutral to light oxidation until about 2000
> >degF. and then go to moderate reduction for the finish.
> >
> >The temmokus smoothed out and were fabulous. The temmoku usually has a
> >slight orange peel surface...this time it looked like one of Ron Roy's.
The
> >reds achieved and held red beautifully. Less crazing on some of the
shinos.
> >All the glazes were smoother and pinholing, even on our pesky Rutile blue
> >(altered moonlight) was minimized. (It did change the color of the blue
> >somewhat). So what gives?
> >
> >The temperature rise is the same, the final temp is the same, the total
> >firing time is the same. The only difference is the earlier reduction.
I'm
> >seeking to understand the mechanics/physics of why that extra reduction
(I
> >assume applied during the sintering or early melt stages) should cause
such
> >a dramatic surface improvement.
> >
> >Tom Wirt
>
> Dear Tom; The reduction changes the Fe2O3 to FeO, which is a flux; thus
> fostering a more complete melt. If you want to try something interesting,
> let the kiln cool normally down to C/1+ and start it up again in Oxidation
> with enough gas supply to hold the temperature steady(need a pyrometer for
> this) for 3 or 4 hours. Then turn off and cool normally. I predict lots of
> iron reds and khakis and dynamite Shinos, and No pinholes. Hank in Eugene
>
Ron Roy on sat 4 mar 00
Hi Tom,
I agree with Hank - any iron is going to help the melt more in reduction. I
suspect your firing was a little longer than the normal oxidation firing?
If so that is going to help glazes smooth out as well.
Perhaps looking at the different way a porcelain affects glaze compared to
a stoneware will help explain what is happening. Glazes usually look better
on porcelain - melted more and smoother - if your clay is melting more
because of the reduced iron there will be some effect on the glaze melt.
I believe you could make your glazes melt more if you wanted to use less
reduction.
RR
>----------------------------Original message----------------------------
>>----------------------------Original message----------------------------
>>OK. We just fired our first load of fully reduced work...reduction (.7 on
>>the probe) starting at cone 010 and continuing out to finish cone 10. We
>>did not go into neutral after body reduction...just stayed at point 7.
>>
>>Our normal pattern is to fire neutral to light oxidation until about 2000
>>degF. and then go to moderate reduction for the finish.
>>
>>The temmokus smoothed out and were fabulous. The temmoku usually has a
>>slight orange peel surface...this time it looked like one of Ron Roy's. The
>>reds achieved and held red beautifully. Less crazing on some of the shinos.
>>All the glazes were smoother and pinholing, even on our pesky Rutile blue
>>(altered moonlight) was minimized. (It did change the color of the blue
>>somewhat). So what gives?
>>
>>The temperature rise is the same, the final temp is the same, the total
>>firing time is the same. The only difference is the earlier reduction. I'm
>>seeking to understand the mechanics/physics of why that extra reduction (I
>>assume applied during the sintering or early melt stages) should cause such
>>a dramatic surface improvement.
>>
>>Tom Wirt
>
>Dear Tom; The reduction changes the Fe2O3 to FeO, which is a flux; thus
>fostering a more complete melt. If you want to try something interesting,
>let the kiln cool normally down to C/1+ and start it up again in Oxidation
>with enough gas supply to hold the temperature steady(need a pyrometer for
>this) for 3 or 4 hours. Then turn off and cool normally. I predict lots of
>iron reds and khakis and dynamite Shinos, and No pinholes. Hank in Eugene
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Hank Murrow on sun 5 mar 00
>----------------------------Original message----------------------------
>Tom,
>
>I'm new at the reduction firing also but I've read Nils Lou's book Art of
>Firing and talked with several "experts" I have been told that body
>reduction occurs beginning about 1650 F and lasts thru about 1850 F. If your
>not reducing earlier than 2000 C you might be missing your body reduction.
>My reading is that reduction is important two times; once for body reduction
>and secondly for glaze reduction which begins at about 2010 F. Nils
>indicates he starts reduction about 1650 F and maintains 0.63-0.65 on the
>oxyprobe from 2010 F; for the body reduction he keeps the oxyprobe between
>0.45-0.56. Having fired my kiln with Nils in the past 2 months and twice
>since by myself, I can assert that I've followed this procedure with really
>great results. I am also told that if you reduce too early you can get
>carbonization of your body and actually cause structural weakness. I'm
>interested in Hank's recommendation and since I have a dual gas/electric I
>plan to turn on the electric as he recommends and hold the temperature
>recommended for 3 hours.
>Best, Tom Sawyer
Wonderful to have that dual capacity for firing down. Do you start the kiln
in electric mode as well? As I said before, try holding at some point
between C/1 and C/5 for the three hours, then cool normally. Report back. I
get great copper yellows this way after a C/10 OX firing. Hank in Eugene
Paul Raymond on sat 6 sep 03
Things change with technology and the new computer controlled electric =
kilns are great. I just bought one (my 1st kiln) and am looking forward =
to learning about how it works. It has a vent system to keep the air =
safe for me and my family which is a huge plus and I can use it year =
round and not be subject to the whims of the weather. It is just not =
practical for me to have a gas kiln, nor can I afford one. The goal here =
is good work. The end justifies the means in this instance.=20
I love fire as much as the next person but due to my situation and =
budget I will have to do pit fires. I don't look at this as a problem, =
but rather I see it as a strength. You take what you have and do your =
best. To say that this way or that way is better is not only silly but =
also stiffling. If we all did it the same way why would we do it at all? =
We could all go to Walmart and buy something, anything, because it would =
not matter.
You take what you know and take what you have and you try to move =
forward.
Paul Raymond
Franklin, TN
Norman van der Sluys on sat 6 sep 03
I have always believed that limitations encourage and enhance creativity
rather than stifle it. Limited resources serve to focus our activities.
I am limited to a gas kiln, one which cost no more than an electric of
the same size (7 cu. ft.) Circumstances have also forced me to reduce
my glaze pallet. I look forward to exploring the three or four I have
chosen in greater depth than I was inclined to do when I had many
choices.
Norman van der Sluys
Benona Pottery
Near the shore of Lake Michigan, taking care of a bumper crop of
tomatoes!
Paul Raymond wrote:
>
> I love fire as much as the next person but due to my situation and budget I will have to do pit fires. I don't look at this as a problem, but rather I see it as a strength. You take what you have and do your best.
>
> You take what you know and take what you have and you try to move forward.
>
Susan Setley on sat 6 sep 03
In a message dated 9/6/03 1:15:49 PM, crazyrays@MSN.COM writes:
<< Things change with technology and the new computer controlled electric
kilns are great. I just bought one (my 1st kiln) and am looking forward to
learning about how it works. It has a vent system to keep the air safe for me and my
family which is a huge plus and I can use it year round and not be subject to
the whims of the weather. It is just not practical for me to have a gas kiln,
nor can I afford one. The goal here is good work. The end justifies the means
in this instance.
I love fire as much as the next person but due to my situation and budget I
will have to do pit fires. I don't look at this as a problem, but rather I see
it as a strength. You take what you have and do your best. To say that this
way or that way is better is not only silly but also stiffling. If we all did it
the same way why would we do it at all? We could all go to Walmart and buy
something, anything, because it would not matter.
You take what you know and take what you have and you try to move forward.
Paul Raymond
Franklin, TN >>
You're absolutely right, Paul. Arguably some of the greatest music ever
written was written by Bach and Mozart, composing under extremely restrictive rules
about how to construct music.
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