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Steven Hill's Firing Schedule For Bisque?


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#61 OffCenter

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Posted 06 June 2013 - 08:39 AM



I finished my first slow firing of SH glazes yesterday with results not even close.
However, I'd be grateful to hear opinions on Baileys Red first.
The firing schedule followed SH's for bisqued as supplied by Min on page one post two of this thread.
The formula for Baileys also supplied by Min on page two post, #28 was followed using Spanish Red Iron.
Only possible difference was synthetic Bone Ash was used instead of natural Bone Ash.
I could not find any reference that advised either type for iron reds.
The fast sample was fired in a neighbors kiln who used the Dawson sitter and no soaking or slow cooling.
The photo shows the slow sample trying to go red on the edges where glaze was thin.
There are also some speckles of red that appear to be crystals on the slow sample.
Both were dipped in same batch, and the only idea I have is to try it thinner, but it is already not very thick.
Thanks.
John255



I've given up (for the time being) on Bailey's Red. Right now I'm getting good results with Juicy Fruit over SCM warm. I subbed Spanish RIO for the RIO in JF. Here is a pitcher (two views) that I unloaded this morning: http://ceramicartsda...wimage&img=2641

Jim


Jim,
Beautiful result on your pitchers.
Attached is what my Juicy Fruit looks like on SCM.
On SH's DVD he emphasized that 60% of the glaze thickness on his pots is SCM.
I followed that and sprayed it on rather thick.
It flowed on all samples, but was quite dry to the touch.
If Min is right about the Iron being weak that could be part of the failure.
Thanks for your input.
John255


Like a lot of his glazes, there are different versions. Does the JF you used on the teabowl have iron in it? It sort of looks like it doesn't. It looks exactly like SCM warm with JF (without iron) over it.

Note: The firing for the pitchers used a schedule very close to one that has already been posted in this thread. Sometime around the time it was approaching peak temp or during the soak, lightning shut off the electricity and I unplugged the kiln. It was off a couple of hours. When I turned the kiln back on I tried to continue the program by guessing where I should start. The JF over SCM came out looking better than usual but I'll never be able to reproduce the program.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#62 John255

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Posted 06 June 2013 - 11:06 AM

Jim,
Yes, I agree that my sample of JF looks like no iron, but it has 7% Spanish RiO.
However, your idea does contribute to Min's suggestion that the iron may be weak in my Bailey's Red sample.
My supplier (Axner) list the Spanish Red I bought as 81% Fe2O. My upcoming line-blend of irons should tell something.
I think I should "Iron while the strike/kiln is hot", don't you.

Too bad about your great firing becoming a mystery.
I've often thought about that happening and wondered what course to take; especially during hurricane season.
However, it does seem to substantiate the critical role the firing variations play.
I'm glad you posted that.
John255
John255

#63 John255

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Posted 06 June 2013 - 11:16 AM

SCM Friends,
I found a guy (Joe Shaw) having great results with SCM over on the Cone6 And Other Ways Forum.
I've posted on that forum, but I find the lay-out hard to get used to, and the activity fairly low.
Joe is very open and supplied his SCM firing sched history.
http://cone6pots.nin...file/RobertShaw
Here is his schedule:
My Present Firing Schedule:(Joe Shaw)

Began use at: 10/20/2012:

200°F/hour to 220° hold 30 minutes

400°F/hour to 2100° no hold

100°F/hour to 2180° 60 min.

40°F/hour to 2140° 30 min.

300°F/hour to 1700° 60 min

50°F/hour to 1600° - off

I slowed the cool-down at the top end and put in additional soak at 1700° toward the end to address some pin-holing some of my glazes were having. This opened up a new look in my SCM / Randy's Red combination. Lost the matte and gained a gloss (that seems inverse of rule of thumb). The gloss is more food friendly. And I gained additional color response.

Firing schedule until:

10/20/2012

200°F/hour to 220° hold 30 minutes
400°F/hour to 2100° no hold
100°F/hour to 2180° 60 min.

100°F/hour to 1700° hold 60 min.
50°F/hour to 1500° hold 30 min then off

This yields some nice crystal growth. Some surfaces seem drier but I think that can be modulated with the amount of SCM I apply. We'll see. It seems like I'm getting some wonderful iron conversion to pyrite (reflective gold-colored crystals in the glaze).

I wasn't getting the rich colors by letting the kiln cool naturally to 1700° so I fired down at 400° per hour.

Firing Schedule until 2/18/12:

200°F/hour to 220° hold 30 minutes
400°F/hour to 2100° no hold
100°F/hour to 2180° 60 min.

400°F/hour to 1700° no hold
50°F/hour to 1600° 30 min then off


Steven Hill 2/13/12:
Ramp 1: 200ºF/hour to 220ºF Hold 1 - 3 hours, depending on the dampness and or thickness of the work.
Ramp 2: 100ºF/hour to 500ºF No hold
Ramp 3: 400ºF to 500ºF/hour to 2100ºF No hold
Ramp 4: 100ºF/hour to 2160ºF-2190ºF 60 Minutes—this temperature is about cone 5, with an hour soak Cone 6 should fall. Not all kilns are calibrated the same, some adjustment may be necessary.
Ramp 5: 9999ºF/hour to 1700ºF No hold
Ramp 6: 50ºF/hour to 1600ºF 45 - 60 minutes
Ramp 7: 50ºF/hour to 1500ºF No hold, kiln off.

Pete Pinnell firing schedule for Tomato Reds:
Ramp 1: 250° F per hour to 2000° no hold.
Ramp 2: 100° F per hour to 2170° F (come 6). No hold
Ramp 3: 150° F per hour to 1900°. No hold.
Ramp 4: 50° F per hour to designated soak temperature.

Hold soak up to three hours

Switch off.











John255

#64 John255

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Posted 14 June 2013 - 12:34 PM

Min,

My hardy congratulations to you for some excellent detective work.
You got it right on my previous samples of Bailey's Red looking greenish signaling low iron content.

My supplier list Spanish Red Iron Ox. as 80% (Fe2O3) so I did a short line-blend trial shown in the attached photo. Jim also suggested that my sample of Juicy Fruit looked like it was short on iron.

When SRiO is increased to 15%, and 20% I get a nice red instead of brown. These samples were fired in neighbors 3.5 cu ft. kiln with no soaking, or extended cooling. More samples will soon be fired using prolonged SH firing schedule.

Bailey's Red formula uses Custer felspar and van Gilders'Red uses Kona F4. That is the only difference, so I tested that and found no difference with 12% SRio and fast cooling.

Bailey's Red:

Custer - 46.6

EPK - 4

Bentonite - 2

Bone Ash - 15

Lithium Carb - 4

Talc - 16.9

Silica - 11.5

Red Iron Oxide - 11.5

You may also be interested in noting that both formulas are quite low in alumina having only 4% EPK and no other alumina source elements. This means the glaze will not hold up well to abrasion of knives and forks in daily use making may be best for decorative purposes. Note the "X" scratched on the Custer sample from one pass with a knife.

John255

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John255

#65 Min

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Posted 14 June 2013 - 02:05 PM

Min,

My hardy congratulations to you for some excellent detective work.
You got it right on my previous samples of Bailey's Red looking greenish signaling low iron content.

My supplier list Spanish Red Iron Ox. as 80% (Fe2O3) so I did a short line-blend trial shown in the attached photo. Jim also suggested that my sample of Juicy Fruit looked like it was short on iron.

When SRiO is increased to 15%, and 20% I get a nice red instead of brown. These samples were fired in neighbors 3.5 cu ft. kiln with no soaking, or extended cooling. More samples will soon be fired using prolonged SH firing schedule.

Bailey's Red formula uses Custer felspar and van Gilders'Red uses Kona F4. That is the only difference, so I tested that and found no difference with 12% SRio and fast cooling.

Bailey's Red:

Custer - 46.6

EPK - 4

Bentonite - 2

Bone Ash - 15

Lithium Carb - 4

Talc - 16.9

Silica - 11.5

Red Iron Oxide - 11.5

You may also be interested in noting that both formulas are quite low in alumina having only 4% EPK and no other alumina source elements. This means the glaze will not hold up well to abrasion of knives and forks in daily use making may be best for decorative purposes. Note the "X" scratched on the Custer sample from one pass with a knife.

John255

I'm glad you got such good results! Now if we can just lower the expansion of SCM.....

Min

#66 John255

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Posted 14 June 2013 - 04:50 PM

Min,
OK.
I thought it significant that Bailey's will go red without the prolonged soaking around 1600F.
However, I'm expecting even more richness with the soak.
You have mentioned expansion with SCM with your clay body.
I would try the usual increase of silica to lower expansion, but probably that may affect the crystal magic?

However, looking at the formula Wollastonite that is half silica, half calcium could be subbed for Whiting to gain some silica while keeping the fluxing action of calcium.
Whiting has a high LOI anyway.
May be worth a try.
John255

John255

#67 OffCenter

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Posted 14 June 2013 - 05:03 PM

Min,

My hardy congratulations to you for some excellent detective work.
You got it right on my previous samples of Bailey's Red looking greenish signaling low iron content.

My supplier list Spanish Red Iron Ox. as 80% (Fe2O3) so I did a short line-blend trial shown in the attached photo. Jim also suggested that my sample of Juicy Fruit looked like it was short on iron.

When SRiO is increased to 15%, and 20% I get a nice red instead of brown. These samples were fired in neighbors 3.5 cu ft. kiln with no soaking, or extended cooling. More samples will soon be fired using prolonged SH firing schedule.

Bailey's Red formula uses Custer felspar and van Gilders'Red uses Kona F4. That is the only difference, so I tested that and found no difference with 12% SRio and fast cooling.

Bailey's Red:

Custer - 46.6

EPK - 4

Bentonite - 2

Bone Ash - 15

Lithium Carb - 4

Talc - 16.9

Silica - 11.5

Red Iron Oxide - 11.5

You may also be interested in noting that both formulas are quite low in alumina having only 4% EPK and no other alumina source elements. This means the glaze will not hold up well to abrasion of knives and forks in daily use making may be best for decorative purposes. Note the "X" scratched on the Custer sample from one pass with a knife.

John255


Hey, John, great test results. (BTW, you really did a great job on the picture. Looks like something out of a book.) Have you tried High Purity RIO? I don't know the % but, obviously, from the name it should be above all the others. I've tired it a couple of times but it speckled so badly (and at that time everything I did with SRIO was looking good) that I didn't keep testing it. 15% of HPRIO should be something like 20% of RIO or SRIO. Thanks for posting this info and pics. I'm anxious to try JF with more SRIO.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#68 TJR

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Posted 14 June 2013 - 05:22 PM

John,jim;
I'm looking at your conversation over Bailey's Red. I am not a cone 6 guy, but I have a couple of suggestions.
1.Rewrite your formula like this;
Custer 46.6
E.P.K. 4.0
Bone Ash 15.0
Lith Carb. 4.0
Talc 16.9
Silica 11.5
Bent. 2.0
Total ----
100
R.I.O. 11.5
Then you can see the percentage of iron you are adding to the glaze.
2.The Bentonite is also providing alumina to the glaze. You could up it to 3% with any noticable difference to the glaze colour, but the surface would be harder.
TJR.
You could also move the bentonite to the additives section, but that would affect your total, and change it from 100% to 98%.
T.

#69 John255

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Posted 14 June 2013 - 08:22 PM

Jim,
Thank you for the comments on the photography. I've been at it for a very long time.
Yes, it seems we are dealing with a subject that has been very easy to overlook; the purity of RiO.
I have you and Min to thank for this revelation.
I had a similar experience with RiO going birds-egg speckled. See attached
Interesting to note that the normally white tin was colored dark ivory overall in addition to the dark crystal clusters.
The iron and tin were used in a high-calcium mat formula.
I'm not sure if the result is from the quality of iron or the combination of iron and calcium.
John255

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John255

#70 OffCenter

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Posted 15 June 2013 - 07:53 AM

Jim,
Thank you for the comments on the photography. I've been at it for a very long time.
Yes, it seems we are dealing with a subject that has been very easy to overlook; the purity of RiO.
I have you and Min to thank for this revelation.
I had a similar experience with RiO going birds-egg speckled. See attached
Interesting to note that the normally white tin was colored dark ivory overall in addition to the dark crystal clusters.
The iron and tin were used in a high-calcium mat formula.
I'm not sure if the result is from the quality of iron or the combination of iron and calcium.
John255


Yeah, the iron looks pretty bad there.
E pur si muove.

"But it does move," said Galileo under his breath.

#71 clay lover

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Posted 15 June 2013 - 07:54 AM

John, are you having any trouble with the 2nd glaze staying on the test tile when you dip? I have tried repeatedly to dip various glazes over the SCM, warm and cool, and the SCM dries on the tile immediately but the 2nd glaze WILL NOT dry. It looks like the test tile with the dry SCM is 'sort of greasy. I have to use a heat gun to get the combo dry enough to handle and get in the kiln. I have tried this several times with different 2nd glazes, all ones that behave well on their own. Always get the same results. It would be nice to dip these tests, changing , rinsing, the spray guns for a tiny amount seems laborious.

#72 John255

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Posted 15 June 2013 - 08:45 AM

Clay Lover,
Wow!
Must say I don't know what's going on with your dipping SCM.
If the SCM dries quickly as you say then bisque firing must be OK. Have you checked your bisque with witness cones?
I was able to double dip OK, but the SCM has to be thin or running will be a problem. See photo.
About spraying, I just bought a HVLP gun from Harbor Freight $13 and it is so much better than syphon, I'm going back for several more guns for multipul colors.
You can easily mix the glaze that is settling in the cup by covering the exit hole with finger causing back pressure to mix the stock.
I also find a glaze planning check-off sheet handy for multiple layers.
Good luck with that. Wish I could be of more help.
John255

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John255

#73 JBaymore

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Posted 15 June 2013 - 10:52 AM

Here's the molecular formula for the glaze:

------------------------------------------------------------
Baily's Red Cone 6
Code Number:
=========================================

Custer Feldspar............. 46.60
EP Kaolin................... 4.00
Bentonite................... 2.00
Bone Ash.................... 15.00
Lithium Carbonate........... 4.00
Talc........................ 16.90
Silica...................... 11.50
Iron Oxide Red.............. 11.50
=========
111.50

CaO 0.33* 8.02
Li2O 0.12* 1.53
MgO 0.29* 5.10
K2O 0.11* 4.42
Na2O 0.05* 1.37
P2O5 0.10* 5.98
TiO2 0.00 0.01
Al2O3 0.21 9.23
SiO2 2.08 53.93
Fe2O3 0.15 10.41

Cost: 0.17
Calculated LOI: 4.44
Imposed LOI:
Si:Al: 9.91
SiB:Al: 9.91
Thermal Expansion: 7.19
Formula Weight: 231.58


Date: 2013-06-15
ID: Baily's Red Cone 6.XML

------------------------------------------------------------------


Using Cooper and Green Limits...... it is slightly undersupplied in both alumina and silica. Alumina/silica ratio is pretty good. If you bring one up.... bring up the other too.

best,

......................john



EDIT: Fixed word "rations" to what it was supposed to be "ratio".
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#74 OffCenter

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Posted 15 June 2013 - 11:18 AM

John, are you having any trouble with the 2nd glaze staying on the test tile when you dip? I have tried repeatedly to dip various glazes over the SCM, warm and cool, and the SCM dries on the tile immediately but the 2nd glaze WILL NOT dry. It looks like the test tile with the dry SCM is 'sort of greasy. I have to use a heat gun to get the combo dry enough to handle and get in the kiln. I have tried this several times with different 2nd glazes, all ones that behave well on their own. Always get the same results. It would be nice to dip these tests, changing , rinsing, the spray guns for a tiny amount seems laborious.


That is interesting, Clay Lover, someone else is having problems dipping SCM tests at this thread http://ceramicartsda..._0&#entry36899. His glazes are peeling. I use an airbrush to test glazes over SCM on test tiles which is a lot faster to use and easier to clean than spray guns. I think spraying would solve your problem since it sounds like you're just getting too much water on the tile. Doc over at the other thread watered his SCM and other glazes down to be able to dip them and get about the thickness of spraying. Maybe you did the same? I have dipped SCM and the glaze or glazes to go over it and did have a problem with thin test tiles getting waterlogged but it never seemed "sort of greasy" and it wasn't a big problem. Even though it's a pain, spraying will give you more accurate results since I assume the application on the pot will be spraying. Another option is to make your test tiles a lot thicker so they can absorb more water when you dip them.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#75 OffCenter

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Posted 15 June 2013 - 11:25 AM

Here's the molecular formula for the glaze:

------------------------------------------------------------
Baily's Red Cone 6
Code Number:
=========================================

Custer Feldspar............. 46.60
EP Kaolin................... 4.00
Bentonite................... 2.00
Bone Ash.................... 15.00
Lithium Carbonate........... 4.00
Talc........................ 16.90
Silica...................... 11.50
Iron Oxide Red.............. 11.50
=========
111.50

CaO 0.33* 8.02
Li2O 0.12* 1.53
MgO 0.29* 5.10
K2O 0.11* 4.42
Na2O 0.05* 1.37
P2O5 0.10* 5.98
TiO2 0.00 0.01
Al2O3 0.21 9.23
SiO2 2.08 53.93
Fe2O3 0.15 10.41

Cost: 0.17
Calculated LOI: 4.44
Imposed LOI:
Si:Al: 9.91
SiB:Al: 9.91
Thermal Expansion: 7.19
Formula Weight: 231.58


Date: 2013-06-15
ID: Baily's Red Cone 6.XML

------------------------------------------------------------------


Using Cooper and Green Limits...... it is slightly undersupplied in both alumina and silica. Alumina/silica rations is pretty good. If you bring one up.... bring up the other too.

best,

......................john


The SCM warm that Bailey's is often used over has enough alumina to help but is short on silica.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#76 Wyndham

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Posted 15 June 2013 - 01:16 PM

Jim posted earlier in the thread

I think that one is okay. Here's what I have for SCM Warm
Custer ... 39.6
Whiting ... 14.9
Strontium Carb ... 10.9
EPK ... 12.9
Frit 3124 ... 3.9
Lithium Carb ... 3.9
Titanium Diox ... 11.9
Bentonite ... 2.0
Yellow Iron Ox ... 2.5


Something that was passed on to me that might be worth trying is using calcined epk for about half of clay in the recipe and regular epk for the rest. This will cut down on the peeling off of some glazes when a second layer is dipped or sprayed.

I use this idea when my glaze calls for 10% or more of clay and it has always helped.
Hope this helps
Wyndham

#77 OffCenter

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Posted 15 June 2013 - 01:27 PM

Jim posted earlier in the thread

I think that one is okay. Here's what I have for SCM Warm
Custer ... 39.6
Whiting ... 14.9
Strontium Carb ... 10.9
EPK ... 12.9
Frit 3124 ... 3.9
Lithium Carb ... 3.9
Titanium Diox ... 11.9
Bentonite ... 2.0
Yellow Iron Ox ... 2.5


Something that was passed on to me that might be worth trying is using calcined epk for about half of clay in the recipe and regular epk for the rest. This will cut down on the peeling off of some glazes when a second layer is dipped or sprayed.

I use this idea when my glaze calls for 10% or more of clay and it has always helped.
Hope this helps
Wyndham


Good post, Wyndham. That's very helpful. I suggested that the guy who started the following thread about glazes over SCM peeling check out your post here. http://ceramicartsda..._0&#entry36899.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#78 John255

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Posted 15 June 2013 - 01:48 PM

Clay Lover,
The advice Jim is posting about dipping vs. spraying for SCM is right on.

I found it necessary to go to much larger pieces, and spraying. See attached.

At present I'm almost ready to go for another kiln load with SCM sprayed much thinner than before with companion glazes that contain more RiO, but I have a house full of company.

Changing glazes with a single gun can be a pain, but with a written plan the underglazes can all be done first then all the greens/browns/reds etc. combinations are done in sequence one color at a time to minimize changing.

Hang in there.

John255


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#79 docweathers

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Posted 15 June 2013 - 03:04 PM

From summer of 2011 his schedule for glaze firing if he used bisqued not raw pots:

segment 1 - 200F/hr - 220 - hold 30 mins if you have raw cone packs in the firing

segment 2 - 400F/hr - 2100 - 0 hold

segment 3 - 100F/hr - 2170 - 30 to 60 min hold until ^6 falls, tweaking required

segment 4 - 9999F/hr - 1700 - 0 hold

segment 5 - 50F/hr - 1600 - 60 min hold

segment 6 - 50F/hr - 1500 - Off

He says that since kilns are calibrated differently and he doesn't use bisque pots that the above schedule would be some approximation of what he would use.

Min



Here is a little more recent and slightly different version
Steven Hill 2/13/12:
Ramp 1: 200ºF/hour to 220ºF Hold 1 - 3 hours, depending on the dampness and or thickness of the work.
Ramp 2: 100ºF/hour to 500ºF No hold
Ramp 3: 400ºF to 500ºF/hour to 2100ºF No hold
Ramp 4: 100ºF/hour to 2160ºF-2190ºF 60 Minutes—this temperature is about cone 5, with an hour soak Cone 6 should fall. Not all kilns are
calibrated the same, some adjustment may be necessary.
Ramp 5: 9999ºF/hour to 1700ºF No hold
Ramp 6: 50ºF/hour to 1600ºF 45 - 60 minutes
Ramp 7: 50ºF/hour to 1500ºF No hold, kiln off.

Larry

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Pottery
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#80 John255

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Posted 16 June 2013 - 11:13 AM


From summer of 2011 his schedule for glaze firing if he used bisqued not raw pots:

segment 1 - 200F/hr - 220 - hold 30 mins if you have raw cone packs in the firing

segment 2 - 400F/hr - 2100 - 0 hold

segment 3 - 100F/hr - 2170 - 30 to 60 min hold until ^6 falls, tweaking required

segment 4 - 9999F/hr - 1700 - 0 hold

segment 5 - 50F/hr - 1600 - 60 min hold

segment 6 - 50F/hr - 1500 - Off

He says that since kilns are calibrated differently and he doesn't use bisque pots that the above schedule would be some approximation of what he would use.

Min



Here is a little more recent and slightly different version
Steven Hill 2/13/12:
Ramp 1: 200ºF/hour to 220ºF Hold 1 - 3 hours, depending on the dampness and or thickness of the work.
Ramp 2: 100ºF/hour to 500ºF No hold
Ramp 3: 400ºF to 500ºF/hour to 2100ºF No hold
Ramp 4: 100ºF/hour to 2160ºF-2190ºF 60 Minutes—this temperature is about cone 5, with an hour soak Cone 6 should fall. Not all kilns are
calibrated the same, some adjustment may be necessary.
Ramp 5: 9999ºF/hour to 1700ºF No hold
Ramp 6: 50ºF/hour to 1600ºF 45 - 60 minutes
Ramp 7: 50ºF/hour to 1500ºF No hold, kiln off.


Doc,
Thanks for posting the latest SH schedule.
Looks like he's lengthening the 2nd ramp probably for issues with his single-fire ware in that temperature range?
With bisqued ware I had to slow down the 3rd ramp to off-set a slight amount of bloating on the surface of the self-supporting cones.
375F/hour to 2100F cleared up the problem in my small test kiln.
Regards,
John255






John255




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