Steven Hill's Firing Schedule For Bisque?

[OffCenter]

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

 

 

 

 

 

Hi John,

 

 

Hmm, isn't glaze testing fun? I pulled out my Michael Bailey Glazes book and had another look at what he wrote about iron. Apologies if you have already read this, he states that the strength of the iron is the most important thing in the glaze and the one he used for the example in his book produced "greens and greeny browns up to7%, bright orange at 10 to 13% with a gradual transition from orange to dark satin brown at 24%". That being said, none of his lower rio sample tiles have the hares fur of green that yours show. It also appears that your tests are more of a gloss glaze finish than the satin finish I get from iron reds.

 

The test tile below is a tweaked version of VanGilders Iron Red, the top third of the tile has 3 dips of glaze, no trace of green fur. Let me know if you want the recipe, I tweaked it to lower the expansion to fit my clay better. Do you have access to other types of iron or from other suppliers? If you like I can scan the couple pages in Bailey's book and email it to you. (I used the S.Hill slow cool down ramp on the tile below.)

 

Min

 

 

It looks pretty good at the bottom but there is so much glare you can't really see the glaze well enough to know what it really looks like. Got a better pic?

 

Jim

[Wyndham]

I want to share something I tested many years ago. I was wondering what the difference was between light & dark rutile, mainly because light rutile cost more.

On a whim, I put a batch of dark rutile in a bisked bowl and fired it with the other greenware to Cone 06 bisk. The result was light rutile.

 

What does this have to do with the iron we use, well I don't know but I think I might fire some red iron oxide like I did with the rutile and see if there is a difference. I might have to fire the iron at a lower temp, around 1200 f as I'm not sure what temp iron starts to fuse, as I just want it to sinter the iron oxide.

I might even mix some bone ash in another test bowl and use these in some test.

 

Btw I had a kiln mishap where my 220 leads into the kiln shorted, so I have some rewiring to do before I can test. not a big issue just a tedious, job I'm putting off for a awhile.

 

Later Wyndham

[Min]

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

 

 

 

 

 

Hi John,

 

 

Hmm, isn't glaze testing fun? I pulled out my Michael Bailey Glazes book and had another look at what he wrote about iron. Apologies if you have already read this, he states that the strength of the iron is the most important thing in the glaze and the one he used for the example in his book produced "greens and greeny browns up to7%, bright orange at 10 to 13% with a gradual transition from orange to dark satin brown at 24%". That being said, none of his lower rio sample tiles have the hares fur of green that yours show. It also appears that your tests are more of a gloss glaze finish than the satin finish I get from iron reds.

 

The test tile below is a tweaked version of VanGilders Iron Red, the top third of the tile has 3 dips of glaze, no trace of green fur. Let me know if you want the recipe, I tweaked it to lower the expansion to fit my clay better. Do you have access to other types of iron or from other suppliers? If you like I can scan the couple pages in Bailey's book and email it to you. (I used the S.Hill slow cool down ramp on the tile below.)

 

Min

 

 

It looks pretty good at the bottom but there is so much glare you can't really see the glaze well enough to know what it really looks like. Got a better pic?

 

Jim

 

Sorry about the last pic, had the flash on. I agree with Jim's earlier post about needing to spray the red over SCM to get S.Hill's tones. - Min

[OffCenter]

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

 

 

 

 

 

Hi John,

 

 

Hmm, isn't glaze testing fun? I pulled out my Michael Bailey Glazes book and had another look at what he wrote about iron. Apologies if you have already read this, he states that the strength of the iron is the most important thing in the glaze and the one he used for the example in his book produced "greens and greeny browns up to7%, bright orange at 10 to 13% with a gradual transition from orange to dark satin brown at 24%". That being said, none of his lower rio sample tiles have the hares fur of green that yours show. It also appears that your tests are more of a gloss glaze finish than the satin finish I get from iron reds.

 

The test tile below is a tweaked version of VanGilders Iron Red, the top third of the tile has 3 dips of glaze, no trace of green fur. Let me know if you want the recipe, I tweaked it to lower the expansion to fit my clay better. Do you have access to other types of iron or from other suppliers? If you like I can scan the couple pages in Bailey's book and email it to you. (I used the S.Hill slow cool down ramp on the tile below.)

 

Min

 

 

It looks pretty good at the bottom but there is so much glare you can't really see the glaze well enough to know what it really looks like. Got a better pic?

 

Jim

 

Sorry about the last pic, had the flash on. I agree with Jim's earlier post about needing to spray the red over SCM to get S.Hill's tones. - Min

 

 

That's getting close to a really nice rich red. I imagine it looks even better over a larger area and over SCM.

 

Jim

[John255]

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

 

 

 

[John255]

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

 

 

 

 

 

Hi John,

 

 

Hmm, isn't glaze testing fun? I pulled out my Michael Bailey Glazes book and had another look at what he wrote about iron. Apologies if you have already read this, he states that the strength of the iron is the most important thing in the glaze and the one he used for the example in his book produced "greens and greeny browns up to7%, bright orange at 10 to 13% with a gradual transition from orange to dark satin brown at 24%". That being said, none of his lower rio sample tiles have the hares fur of green that yours show. It also appears that your tests are more of a gloss glaze finish than the satin finish I get from iron reds.

 

The test tile below is a tweaked version of VanGilders Iron Red, the top third of the tile has 3 dips of glaze, no trace of green fur. Let me know if you want the recipe, I tweaked it to lower the expansion to fit my clay better. Do you have access to other types of iron or from other suppliers? If you like I can scan the couple pages in Bailey's book and email it to you. (I used the S.Hill slow cool down ramp on the tile below.)

 

Min

 

 

Min,

Your test tile looks great.

That is a keen observation about the greenish streaks on my Bailey sample.

I wonder if we are sure Bailey is talking about oxidation. I know small amounts of iron in reduction goes green.

However it is a good point to pursue. I will do a line-blend of different irons in next firing.

I have VanGilders formula thank you. Will try that one too.

Thank you.

John255

 

 

 

 

 

[John255]

I want to share something I tested many years ago. I was wondering what the difference was between light & dark rutile, mainly because light rutile cost more.

On a whim, I put a batch of dark rutile in a bisked bowl and fired it with the other greenware to Cone 06 bisk. The result was light rutile.

 

What does this have to do with the iron we use, well I don't know but I think I might fire some red iron oxide like I did with the rutile and see if there is a difference. I might have to fire the iron at a lower temp, around 1200 f as I'm not sure what temp iron starts to fuse, as I just want it to sinter the iron oxide.

I might even mix some bone ash in another test bowl and use these in some test.

 

Btw I had a kiln mishap where my 220 leads into the kiln shorted, so I have some rewiring to do before I can test. not a big issue just a tedious, job I'm putting off for a awhile.

 

Later Wyndham

 

Let us know how your iron test turns out.

Watch that 230V. It is lethal.

John255

 

 

 

[John255]

I was a bit surprised to see the probably too thick SCM be so dry and yet running off the pots.

I also did some small tiles quickly dipping SCM to compare fired slow and fast cooling.

The attached shows SCM dipped in Baileys Red.

The slow cooled was a closer to red than any of the other pots in the firing.

Thanks for your thoughts.

John255

[OffCenter]

I was a bit surprised to see the probably too thick SCM be so dry and yet running off the pots.

I also did some small tiles quickly dipping SCM to compare fired slow and fast cooling.

The attached shows SCM dipped in Baileys Red.

The slow cooled was a closer to red than any of the other pots in the firing.

Thanks for your thoughts.

John255

 

 

John, when you (and others here) say SCM I assume it is the "warm" version with yellow iron oxide. The "cool" version doesn't have yellow iron and is slightly different in base chems. It looks good under blues and greens but not under saturated irons. The test tile of slow fired Bailey's Red looks good except for the running. I like the color. I think the run is caused by both being too thick. It's almost impossible to get the same results dipping that you get spraying.

 

Jim

[John255]

I was a bit surprised to see the probably too thick SCM be so dry and yet running off the pots.

I also did some small tiles quickly dipping SCM to compare fired slow and fast cooling.

The attached shows SCM dipped in Baileys Red.

The slow cooled was a closer to red than any of the other pots in the firing.

Thanks for your thoughts.

John255

 

 

John, when you (and others here) say SCM I assume it is the "warm" version with yellow iron oxide. The "cool" version doesn't have yellow iron and is slightly different in base chems. It looks good under blues and greens but not under saturated irons. The test tile of slow fired Bailey's Red looks good except for the running. I like the color. I think the run is caused by both being too thick. It's almost impossible to get the same results dipping that you get spraying.

 

Jim

 

 

Jim,

Yes your are right. I only used SCM warm with 2% yellow iron for this firing.

I was also getting acquainted with my first LPHV gravity feed spray gun.

I've been using syphon type for years and I will never think of going back.

I'm stunned by reduced amount of overspray, and the ease of use.

Should have done this years ago.

John255

 

 

 

 

 

[OffCenter]

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

[John255]

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]

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.ning.com/profile/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]

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

[Min]

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

[John255]

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

[OffCenter]

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

[TJR]

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.

[John255]

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

[OffCenter]

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.

[clay lover]

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.

[John255]

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

[Guest JBaymore]

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".

[OffCenter]

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://ceramicartsdaily.org/community/topic/4247-multi-layer-glazes-peeling/page__pid__36899__st__0entry36899. 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

[OffCenter]

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