High School Teacher, glaze making

[Judd]

I'm an art teacher in Arkansas. My school bought a kiln, a Paragon Dragon with a Bartlett controller. In one of my storage closets I found about 1000 pounds of this kind of Cone 10 clay:

 

Dick Blick, Cone 10

Stoneware Clay

Item # 30517-1050

 

I want to make a plain old white glaze, something I can add oxides or crushed glass to and get some interesting results. Does anyone have a glaze formula that would be compatible with the clay? I understand I'm asking a lot, but any suggestions would be greatly appreciated. In years to come, I'll do things differently, but right now I'm using what previous teachers had bought.

 

Thank you. Not trying to be a P.I.T.A., but I have to educate our nation's future leaders. woo...

[Guest JBaymore]

Welcome to the forums.

 

Do you have an existing stock of chemicals also in the storage area.... or will you have to buy stuff specifically for this glaze?

 

best,

 

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

[Judd]

Nope. No supply. It'll probably be coming out of my pocket, by the way.

 

 

[GEP]

Here is a cone 10 white glaze recipe attributed to Tom Coleman. I should note that I have not yet fired this myself (most of my work is cone 6), but I needed a white glaze for a cone 10 firing this fall. I chose this recipe for its simplicity, and its common, inexpensive ingredients. And also that it is described as being durable enough for everyday dinnerware.

 

 

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White Crusher Glaze Cone 9-10 by Tom Coleman 

 

    Custer Feldspar 29

 

    Whiting 11

 

    Talc 11

 

    Kaolin 26

 

    Silica 20

 

This is a glaze recipe that I got from a Tom Coleman workshop many years ago. It is a great glaze for doing brushwork and great for any functional work. Great for dinnerware. No crazing and holds up well under daily use. It is a buttery semi-matt glaze.

 

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One thought that you should check on ... not all electric kilns can go up to cone 10. Make sure yours can before you fire it that hot.

 

Good luck!

 

 

Mea

[OffCenter]

If your school was willing to buy a Paragon Dragon, then it should be willing to buy the chemicals you need to use the kiln. The glaze GEP listed above is a good one to start with because none of those chemicals are expensive and they are most of the most used chemicals in a cone 6-10 glaze lab. Also, even if the new kiln does go to cone 10 easily, it will last longer and use less energy, take less time to fire and you'll have a better pallet of colors if you fire to cone 6 instead of 10. It's still stoneware and just as good as cone 10. I just looked it up and that half ton of clay from Blick is rated as a cone 5-10 stoneware so you don't have to fire it to cone 10.

 

Jim

[Mark C.]

I would look toward firing less than cone 10 with that clay-it will make the kiln last longer

If not hear is a another rock solid cone 9-12 white glaze that can be satin matt or shiny can grow crystals and will not craze and is great for toughness in everyday wares.I have used this for 40 years now with solid results.You can add colorants or whatever.This has a few more materials than Toms but still cheap.

 

 

Honey White

OM4 450

Colemanite(gerstley borate) 750

Dolomite 920

Talc 882

Silica 1198

Custar spar 2570

 

Mark

[Guest JBaymore]

Manufacturers state long firing ranges on their clay bodies so that they don't have to stock so many clay bodies for various ranges. Cuts down on inventory issues.

 

Cone 5 to 10 is an ENORMOUS firing range. I'd LOVE to see the technical specs on that body across that range. They must have a GENIUS in the lab to accomplish that.

 

If that clay is properly fired at 10 then it is way underfired at 5...and if it is fired properly at 5 then it is way overfired at 10. Likely it is a cone 7-8 formulation....... and is not as good as you'd really want at EITHER cone 5 or at cone 10.

 

Personally I'd fire it to cone 9-10 until you use it all up. Then decide if cone 6 (or any other cone range) is what you want to work at. Better yet....... do some testing work on it.

 

 

 

And I agree on the "get them to buy it" idea. If they want ceramics........ tthey need to cough it up. If not... teach drawing instead. If you pay out of your pocket..... they'll just take even MORE advantage of you on the next issue. Yeah... the kids matter. But you'll do more for MORE kids if you force the district to actually committ to the art program.

 

best,

 

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

[TJR]

Judd;

I agree wholeheartedly with what John has said. I teach highschool art in Canada. You do not want to be paying money out of your own pocket for art supplies. You also do not want to be firing to cone 10 in your classroom. You want to be firing to cone 06, not cone 6. You want to buy some low fire clay and jars of commercial glazes in bright colours. Go on line and price out some glazes. Then go to your principal and tell him/her what it is going to cost. Put the stoneware clay up for sale or donate it.

The reason you want to be at cone 06 is that you can bisque and glaze in the same kiln. Be firm. We art teachers need some solidarity here.

TJR.

[Judd]

Thank you so much for your replies. Cone 8 or 08 sounds great to me. I'm (obviously) a newbee potter.

 

 

[bciskepottery]

"Cone 8 or 08 sounds great to me."

 

But they are not the same . . . cone 08 would be for a bisque firing, while cone 8 would be for a glaze firing. A cone 8 glaze will not melt properly at cone 08.

[neilestrick]

Since you're teaching high school, I would fire cone 6, not low fire. Kids at that age are more mature about their color choices, and often want durable, functional pieces that they can actually use. If they want bright colors you can get them, but you can also get many glazes with nice depth that are much more interesting than the low fire choices.

[Pres]

Since you're teaching high school, I would fire cone 6, not low fire. Kids at that age are more mature about their color choices, and often want durable, functional pieces that they can actually use. If they want bright colors you can get them, but you can also get many glazes with nice depth that are much more interesting than the low fire choices.

 

 

I heartily agree with Neil here. In the future run to cone 5-6 and be happy with the wide variety of color you can get there. However, as others have eluded here the clay body you have now should be fired to a higher range for better vitrification. You might try 7-8. As far as glaze mixing you can find several resources on starting material purchases that could get you both ranges once you decide to change over to 5-6. 1000 lbs. in a classroom setting will not last as long as you might think, depending of course on your curriculum structure, number of classes, and recycling capabilities. You may in the future find that adult classes would help you supplement the needs of this media. I did it in the winter for several years, and was lucky enough to get people from administration in the class. Do you think that helped at budget time? Good luck!

[yedrow]

I too wouldn't fire an electric kiln to cone 10 just for the clay. Another thing, in my experience there are many more glaze selections in the popular firing ranges like 10 and 6 (and I think 04), than there are for cones that are very far from those numbers. This means that there is a lot of experience in those glazes to be had. The Coleman glaze mentioned may have been worked and tweaked by hundreds of potters and survived. Other glazes, like clay bodies, come and go because they have no good use. Their recipes though still haunt the internet.

 

Joel.