Help Needed with Glaze Recipe - MarieP

[Bill Kielb]

9 hours ago, Min said:

Another approach would be to use glaze calc software to redo recipes to include the Kingman spar. In the recipe below the combined KNaO matches Mark's recipe. Other oxide levels are the same in both formulas. Like you can see the main differences are a decrease in the amount of Kingman spar needed and an increase in the silica needed with the Dolomite and Whiting amounts tweaked.

Kingman 318

Dolomite 195

Whiting 33

EPK 245

Silica 256

total 1047 (I rounded the numbers off)

(Tin oxide 1% plus Zircopax 5%) 

This looks nice!

Direct substitution with no change however also looks good as well with a slightly better flux ratio. I think the Kingsman will be easy to use up and G200 is pretty darn close when it is gone. Of course testing to confirm performance with a clay body is always a necessity.

Good stuff!

[MFP]

Thank you very much, Min. I don't know if you saw in the thread that the missing ingredient was finally found. It was PV clay. So 50 Colemanite, 50 PV clay and 15 Ziropax. We used it without the pax for a clear Raku glaze.   So I am assuming, you would still think there is too much Boron.  Neil did a good job of clarifying how and why some of the changes have come about in glaze formulation and how this has improved the end result.  I don't intend to continue to rely on Kingman as my primary feldspar. I just happened to have a partial sack left. There are only two of those glazes which would function in oxidation....because everyone were scrounging glaze materials in those days, the lion's share of all cone 10 glazes were iron based with a tremendous range of colors in reduction---it was part of what fascinated me about reduction...the range of colors possible with iron alone. . Testing a copper red was considered exotic.  Obviously, that's not going to happen in oxidation----they are all going to be tan to black. I have ordered all the newer chemicals....I especially like the substitution of Strontium for Barium.  Even in the old days I was disturbed handling Barium.   I would be interested in your opinion on a cone 6 porcelain body that actually vitrifies.  Georgies in Portland claims to have one but their prices and shipping charges are outrageous. 

[MFP]

Thank you very much Bill.   I will review the sheet and let you know if I have any questions....the one thing yet to be un-earthed is my glaze book. It is in a tub with other important paperwork that I hope my stupid movers did not screw up and throw away......considerable moving of heavy obstacles is required to get to the tubs of paperwork.  As soon as I find the damn thing I will be happy to share all the Kingman recipes with you.  Like all potters at that time, I was a scrounger.....if someone offered me some of something, I took it whether I used it or not....thinking especially with the Kingman mine shutting down that I might need it some where along the way.  As a result....I have about ten pounds of G-200 that I have never used nor do I have any recipes for it....but I will look on glazy and take you up on your offer.  I am sure that there are a lot of people like me out there....who are returning to pottery after having had to let it go for another profession in the past.....and they are undoubtedly wondering how to adapt their old glazes too. The only other feldspars in use at that time were Cornwall Stone and Custer.  I knew they existed but Kingman dominated my group of potters.....and all our glazes were reduction and iron based....all colors were achieved with iron....yellow, rust, brown,red,  black, green, blue. It was what fascinated me about reduction......that one chemical could be so diverse.  Again, thank you very much, 

[neilestrick]

56 minutes ago, MFP said:

Testing a copper red was considered exotic.  Obviously, that's not going to happen in oxidation----they are all going to be tan to black.

You can make really nice copper reds in oxidation by using silicon carbide for localized reduction. You can also make all sorts of nice iron reds and oranges in oxidation, typically with the addition of bone ash. And yellows and oranges with rutile. You actually have a lot more options for color in cone 6 oxidation than you do in cone 10 reduction, because may colors are more stable at the lower temperature.

[Min]

2 hours ago, MFP said:

Thank you very much, Min. I don't know if you saw in the thread that the missing ingredient was finally found. It was PV clay. So 50 Colemanite, 50 PV clay and 15 Ziropax. We used it without the pax for a clear Raku glaze.   So I am assuming, you would still think there is too much Boron.  Neil did a good job of clarifying how and why some of the changes have come about in glaze formulation and how this has improved the end result. 

No problem, anytime. I did read the post about Plastic Vitrox being the missing ingredient and yes there is still far too much boron in the glaze but there are other issues also. Not nearly enough silica or alumina in the glaze to make it what is considered durable by todays standards. Alumina is less than half of what would typically be seen in a durable^10 glaze and silica is about a third less than a lowish level. Having as much silica in a glaze as can be tolerated in addition to adequate alumina levels are important to make a base that is durable. That being said there is nothing nasty to leach out of the glaze so not too much to worry about as long as you don't add copper etc. 

3 hours ago, MFP said:

I would be interested in your opinion on a cone 6 porcelain body that actually vitrifies.  Georgies in Portland claims to have one but their prices and shipping charges are outrageous. 

I haven't had much luck with Georgies claybodies. I've tried several and found the actual absorption figures to be higher with my firings than what Georgies posts. You can make any claybody vitrify, even lowfire bodies can be tight and vitrified if you add enough flux to them. I've used Laguna ^6 Hagi Porcelain and it's definitely vitrified at cone 6 but the colour isn't very white. Frost is another cone 6 Laguna body that vitrifies. I like several of Tacoma Clay Art Centers midrange porcelains, my favourite is CL178 NZ6, it's both very white and translucent when thin. I don't know how much shipping to you would be. I had a ton of their Glacier Porcelain shipped up to me a few years back and the shipping wasn't outrageous.

[MFP]

Thanks Min for your feedback on both counts. Having lived in Oregon for 13 years, I have a healthy skepticism about any claim over there.   I have been going over to Spokane Pottery Supply for clay which he gets from Clay Art Center in Tacoma.  I have had to downsize my thinking from tons to pounds and from gallons to quarts :).  The owner is named Kyle...and as an aside I turned him onto the website today when I was over there.  I bought 50 pounds of "Oregon White" (cone 6)  from him which he stated was comparable to that Silver Falls Porcelain that Georgies has. He also was not a big fan of Georgies.  I have adapted to the white stoneware body I got from him. It's "stickier" than what I was used to and I had to slow down. The body I used previously was very slick and you did two really rapid hard pulls, shaping and then you were done.  The body would not tolerate being messed with any more than that. This new body has to be thrown slower with more water but is quite forgiving in terms of the number of pulls to get the desired result.    I am just so very impressed....and at times overwhelmed....by all the progress has been made since I have been gone!   I like the more science and less guessing :).    All these choices are pretty overwhelming.....like ....there are actually decent commercial celadons.  Not sure about any of the other stuff.  But old habits die hard and I am going to be testing glaze recipes from this network as well as some of the books.  Also...Neil thinks some of my iron glazes might actually not be crap in oxidation.  Now....if I can find my glaze book.....which is in an "important paperwork tub" that I have been unable to locate since the move, I can see about adjusting them for 6.   ( My movers were not real great but all that was available....and of course....all the paperwork tubs have large heavy things in front of them that would have to be moved.)  Thanks again....have to go out and turn pots. 

[MFP]

9 hours ago, Bill Kielb said:

You are welcome, I have sent the spreadsheet. If it helps ........ send me a couple of your old recipes or some you like from Glazy that use g200 if possible  and I will put them in the spreadsheet ( which is a glaze calculator) as an example for you. You may or may not end up interested in glazes. It’s not for everyone but there are many that become inspired and proficient at it and enjoy. Regardless, the basics are simple and most often can help the average potter save hours of exasperation.

its time for me to do a better video anyway, so I would use your solutions as a basis for the video. They would be published on our you tube channel with your permission should you send recipes not in the public domain. We would include in the video a couple conversions to cone six as well.

 

4 hours ago, neilestrick said:

You can make really nice copper reds in oxidation by using silicon carbide for localized reduction. You can also make all sorts of nice iron reds and oranges in oxidation, typically with the addition of bone ash. And yellows and oranges with rutile. You actually have a lot more options for color in cone 6 oxidation than you do in cone 10 reduction, because may colors are more stable at the lower temperature.

That's very interesting. Hopefully, I can get some muscle over here soon to unearth the important paper tubs one of which contains my glaze book, The movers I had weren't the best...and I am worried because I have not seen that tub.    We were throwing so much stuff away in our downsizing that I hope they didn't get confused and throw that tub away. The other items that were in it like marriage and birth certificates can be replaced. The glaze book cannot. The glaze names that I am sure of were Ohata Red, Shupe's Blue, Brown Cow, Brown/Black  in case anyone recognizes them......the other names were simply generic..."chun", "celadon" etc.

4 hours ago, neilestrick said:

You can make really nice copper reds in oxidation by using silicon carbide for localized reduction. You can also make all sorts of nice iron reds and oranges in oxidation, typically with the addition of bone ash. And yellows and oranges with rutile. You actually have a lot more options for color in cone 6 oxidation than you do in cone 10 reduction, because may colors are more stable at the lower temperature.

Thanks Min for your feedback on both counts. Having lived in Oregon for 13 years, I have a healthy skepticism about any claim over there.   I have been going over to Spokane Pottery Supply for clay which he gets from Clay Art Center in Tacoma.  I have had to downsize my thinking from tons to pounds and from gallons to quarts :).  The owner is named Kyle...and as an aside I turned him onto the website today when I was over there.  I bought 50 pounds of "Oregon White" (cone 6)  from him which he stated was comparable to that Silver Falls Porcelain that Georgies has. He also was not a big fan of Georgies.  I have adapted to the white stoneware body I got from him. It's "stickier" than what I was used to and I had to slow down. The body I used previously was very slick and you did two really rapid hard pulls, shaping and then you were done.  The body would not tolerate being messed with any more than that. This new body has to be thrown slower with more water but is quite forgiving in terms of the number of pulls to get the desired result.    I am just so very impressed....and at times overwhelmed....by all the progress has been made since I have been gone!   I like the more science and less guessing :).    All these choices are pretty overwhelming.....like ....there are actually decent commercial celadons.  Not sure about any of the other stuff.  But old habits die hard and I am going to be testing glaze recipes from this network as well as some of the books.  Also...Neil thinks some of my iron glazes might actually not be crap in oxidation.  Now....if I can find my glaze book.....which is in an "important paperwork tub" that I have been unable to locate since the move, I can see about adjusting them for 6.   ( My movers were not real great but all that was available....and of course....all the paperwork tubs have large heavy things in front of them that would have to be moved.)  Thanks again....have to go out and turn pots. 

[Min]

2 hours ago, MFP said:

I bought 50 pounds of "Oregon White" (cone 6)  from him which he stated was comparable to that Silver Falls Porcelain that Georgies has.

Sorry but unless they've changed the recipe I don't think  Oregon White from Tacoma Clay Art is anything like the description of Silver Falls Porcelain from Georgies. From the website about Oregon White: "A grogged white stoneware that is used for slab work and throwing. Slightly open at cone 6, it will fire up to cone 10. Well balanced for glaze fit at both cone 6 and cone 10. Cone 4-6.  Wet Color light gray, Oxidation Color off-white, Reduction Color gray/white, Texture medium smooth, Shrinkage 12.0%, Absorption 4.4%."  Any chance it was one of the clays from this page instead?

BTW there are a couple Ohata recipes on Glazy here. 

[MFP]

Look what I found!!!!   https://www.aqua-calc.com/calculate/volume-to-weight   This gives the weight of common minerals in all kinds of units of measurement!  So....I will be able to determine if any of those materials is the talc Mark needs!  One US cup of talc weighs 1.40828701 pound.   Calcium carbonate is 1.41402447.   So, it's going to be close.  Since I had two fizzers...I am pretty sure there is one of each.   I have no idea what I did to cause this blue.

He must have mis-recalled the name.  Whatever it is I have has no grog.  Maybe the white stoneware with grog I am throwing is the Oregon White.  That description is exactly what it is.  All I know is that it came from Clay Art Center and was milled  in  5/18 and is really hard.  I have had to cut it up and soften it.  Clay Art Center has  "raku " on it....used at  04 for raku, still open at 6 and vitrifies at 10. 

I went out this evening and did something I understand....I put kiln wash on my shelves....even that has changed!  

Thanks again Min.  You're swell!

[liambesaw]

Unfortunately it's not that easy and volume of any powder will not be a normalized weight.  Talc is the easiest powder to identify though, as many here have said it is the only slippery powder.  It actually feels like lubrication on your hands.  

[MFP]

There are two samples I sent to Mark that not only  both fizzed with vinegar but also feel slippery. Calcium carbonate and  ground talc are VERY close in weight. I can at least rule out the heavier or lighter materials by weight.  I might just have to send him both and he will have to test. I don't have any old recipes that will only work with the old talc.  Soapstone talc however is very different in weight from calcium carbonate.  I encourage you to go to the site and look for yourself.  For example a cup of talc is 1.41 pounds whereas dolomite is 0.91 pounds. That is enough of a  difference to rule out the lighter material.  Silica is 1.21 pounds per cup....again...enough of a difference to rule it out as talc.   If Mark....who works with these chemicals every day couldn't figure out the "greasy one", I sure can't. 

[MFP]

On 6/19/2019 at 9:59 PM, MFP said:

There are two samples I sent to Mark that not only  both fizzed with vinegar but also feel slippery. Calcium carbonate and  ground talc are VERY close in weight. I can at least rule out the heavier or lighter materials by weight.  I might just have to send him both and he will have to test. I don't have any old recipes that will only work with the old talc.  Soapstone talc however is very different in weight from calcium carbonate.  I encourage you to go to the site and look for yourself.  For example a cup of talc is 1.41 pounds whereas dolomite is 0.91 pounds. That is enough of a  difference to rule out the lighter material.  Silica is 1.21 pounds per cup....again...enough of a difference to rule it out as talc.   If Mark....who works with these chemicals every day couldn't figure out the "greasy one", I sure can't. 

Interestingly...although the weights differed, the ratios as indicated on the website were exactly the same. There were two almost identical in weight....and the other two were in the respective ratios of silica and dolomite. It will be interesting to see what Mark's tests show. 

[Kosch]

On 6/19/2019 at 8:41 PM, MFP said:

Look what I found!!!!   https://www.aqua-calc.com/calculate/volume-to-weight   This gives the weight of common minerals in all kinds of units of measurement!  So....I will be able to determine if any of those materials is the talc Mark needs!  One US cup of talc weighs 1.40828701 pound.   Calcium carbonate is 1.41402447.   So, it's going to be close.  Since I had two fizzers...I am pretty sure there is one of each.   I have no idea what I did to cause this blue.

He must have mis-recalled the name.  Whatever it is I have has no grog.  Maybe the white stoneware with grog I am throwing is the Oregon White.  That description is exactly what it is.  All I know is that it came from Clay Art Center and was milled  in  5/18 and is really hard.  I have had to cut it up and soften it.  Clay Art Center has  "raku " on it....used at  04 for raku, still open at 6 and vitrifies at 10. 

I went out this evening and did something I understand....I put kiln wash on my shelves....even that has changed!  

Thanks again Min.  You're swell!

Hey there,

I realize this is a very old post, but I stumbled across it researching various clay bodies. I'm guessing the clay you got from Kyle (he is a friend of mine) was Coleman Raku. The description says it has grog but I believe it's supposed to be fairly smooth.

However, I think the clay he carries that is most comparable to Silver Falls is Rainier, which is a medium grey before firing. It's also extremely hard and has to be beat up pretty well to be workable (dropping on the floor a couple of times works). Anyhow, not sure if you'll see this, but hope it helps, even if very late

[MFP]

Yes, I finally figured that out....it's amazing what reading the box will do for you!  Yes...I get Rainier from Kyle. I tried a bunch of different porcelains and I like it the best. It actually is more cooperative than the stoneware I bought from CAC.  I finally figured out that If I want to do plates, I better be prepared to dry them for 3 weeks, no matter what I use. That seems to be the trick with all these new clay bodies. I have been trying Amaco Amix   #11. I get it from School Specialty on ebay....their shipping is $5, no matter what you buy and it makes this very white stoneware affordable. 

Check in on Kyle....it's been a rough road for him lately. 

[liambesaw]

8 minutes ago, MFP said:

Yes, I finally figured that out....it's amazing what reading the box will do for you!  Yes...I get Rainier from Kyle. I tried a bunch of different porcelains and I like it the best. It actually is more cooperative than the stoneware I bought from CAC.  I finally figured out that If I want to do plates, I better be prepared to dry them for 3 weeks, no matter what I use. That seems to be the trick with all these new clay bodies. I have been trying Amaco Amix   #11. I get it from School Specialty on ebay....their shipping is $5, no matter what you buy and it makes this very white stoneware affordable. 

Check in on Kyle....it's been a rough road for him lately. 

I don't know if you're firing cone 10, but a-mix is a cone 10 clay that is marketed as a mid to high fire clay, misleading!  I tried it for mugs at cone 6 and they wept.

[MFP]

Yes....I know they are cone 10 clays that will remain open at 6. I was not planning on using them on anything that would hold liquid. But thanks for letting me know!  I also bought some 38 in the past and it also throws very well. Just not as white.  I am thinking that if I finally make myself fire the gas beast, I will use these 2 for my stoneware.  There is an NZ 10 glassy porcelain that is very good but spendy!  They have a cone 10 porcelain called White Rose which I highly suspect is the cone 10 version of Rainier. It is very similar and a toothy porcelain.