Pkqw: Week 14

[Pres]

Week 14

 

1. A clay body for Barbecue Cookers, fire places and charcoal heaters may be created with a clay that is specialized for that purpose. This clay body is heavily _____________ and porous. The pieces made should be from 3/8 inch to ½ inch dependent of size. Firing range is usually ^2 to ^6.

   1. Vitrified

   2. glazed

   3. grogged

   4. sand based

2. _______________________ is a translucent white ware developed by English potters in their research to duplicate the Chines porcelain. Calcium phosphate is the principle flux and derived from heating animal bones.

   1. Flameware

   2. Fusible clay

   3. Earthenware

   4. Bone China

3. _______________ glaze developed in England as a substitute for lead glazes is a mid-temperature glaze (^2 to ^6) which depends on zinc oxide (12-15%) as one of the principal fluxes.

   1. Ash

   2. Barium

   3. Bristol

   4. Ash

4. _______________, not a glaze, but a process of coloring glazes in which stannic chloride, bismuth sub-nitrate or zinc chlorates introduced into the cooling cycle of the fired kiln at 600-760C. Range.

   1. Flambe

   2. Fuming

   3. Raku

   4. Cullet

 

 

This weeks questions come from text in Advanced Ceramic Manual Technical Data for the Studio Potter, John W. Conrad c. 1987, Falcon Company, Publishing Division

Note from Pres: My well worn copy of this paper back is an excellent stepping off point to more advanced understanding of clay bodies, glazes, and studio processes. Well worth the read. . . if you can find it.

 

 

Answers

1. 3. grogged - Barbecue Cookers, fire places, and charcoal heaters can be made out clay. Several types are manufactured today and have about 1/2†walls for strength and to hold and distribute the heat. They are made Into unusual shapes, have conversational value, and can make cooking and heating enjoyable. The clay body, glaze, and construction techniques are not unusual or particularly different. Most of these items are ï¬red in C/2 to C/6 range. The body is heavy grogged and porous.

2. 4. bone china-Bone china is a translucent, white ware developed by English potters in their research to duplicate the Chinese porcelain. English bone china is translucent and white while some American is translucent and light ivory color. Calcium phosphate is the principle flux and derived from heating animal bones. The body is not plastic, with most ware being slip cast and limited press molding or jigger/jolly spinning. Some throwing bodies are possible. The temperature range is C/8-12.

3. 3. Bristol-Bristol glaze, developed in England as a substitute for lead glazes, is a mid-temperature glaze (C/2 to C/6) which depends on zlnc oxide (12 to 25%) as one of the principal fluxes. The glaze is opaque, rather stiff, and not as smooth and bright as the typical lead glaze. Good for blues and greens.

4. 2. Fuming-Fuming, not a glaze but a process of coloring glazes in which stannic chloride, bismuth subnitrate, or zinc chlorate is introduced into the cooling cycle of the fired kiln at 600 to 760 C range. Using a long handled spoon, small amounts of the material are implemented several times into the spy holes or fire boxes of the kiln. The corrosive smoke travels throughout the kiln and deposits a thin coating on the ware and everything else inside. Stannic will give a transparent pearly or mother-of-pearl coating; zinc will yield green, yellow, brown, or gray cloudy tints on red and white clay bodies; and bismuth gives a lustrous finish. About 1/4 teaspoon of the material per one cubic foot. The fumes are TOXIC!

[S. Dean]

1.  3

2.  4

3.  3

4.  2

[Marcia Selsor]

1-3

2-4

3-3

4-2

[Mark C.]

3

4 

3

2

 

Mail the decoder ring to the FBI this time

[glazenerd]

Hey.. Clay questions.: oh joy!!!

 

3-4-3-2

 

Hint hint: sulfides and chlorides emit fumes when they burn off.

[Joy pots]

1. 3

2. 4

3. 3

4. 2

Joy

[Magnolia Mud Research]

3,4,3,2

[Chilly]

3

4

no idea

2

 

Did you mean to put ash as a choice twice in question 3?

[Judith B]

3, 4, I don't know, 2

 

For question 1, why does using a grogged body clay is necessary for pots that are exposed to direct fire? Are they just more resistant overall?

[Pres]

3

4

no idea

2

 

Did you mean to put ash as a choice twice in question 3?

Good call, no I did not. I usually put the answers in first, then come up with the distrators. In this case. . . . . I goofed! However, for those of you that might have chosen that as the right answer. . . . wrong!

[Pres]

3, 4, I don't know, 2

 

For question 1, why does using a grogged body clay is necessary for pots that are exposed to direct fire? Are they just more resistant overall?

The heavily grogged clay is able to handle expansion and contraction in the body, the sawdust burning out makes the clay more porous and insulating. These clay bodies also often use wallostonite or talc as a flux.

One ^4 body listed is Grog (mixed) 40, Fire clay 35, ball clay 10, wallostonite 10, screened sawdust 5. 

 

I am sure others with much more experience will chime in, and hope that they do.

 

best,

Pres

[Marko]

3

4

3 guessing

2