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Glaze Drip Trays Clay Recipe


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#1 Biglou13

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Posted 25 January 2014 - 09:02 PM

Do any of,you have a recipe for clay to make glaze drip trays/ saucers?

I was going to use a cone 10 body recipe , but thought why a complete /technically sound clay, when something simple and refractory would work.

Was planning. On rolling out some slabs cut some small tiles /saucers.
Any ideas.
We have a few have a few bags of donated epk

Ps. It's for a community studio, non profit, They have bunch of old and crappy shelves.
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#2 bciskepottery

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Posted 25 January 2014 - 09:31 PM

I'd go with the cone 10 clay . . . or sounds like a good use for reclaim, especially if you are just going to roll out the trays/saucers. Using a commercial body eliminates the need for testing a made clay; you could spend more time mixing/refining than worth the cost of the commercial body. If commercial, I'd go with stoneware to preclude any potential issues with plucking, etc. that can happen with porcelain.

#3 Roberta12

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Posted 25 January 2014 - 10:57 PM

Plucking!   I didn't know that was what it was called, but I know what it is and yes, it was with some porcelain scraps I rolled out for drip trays that that happened with!  Hey thanks. 

 

I use scrap stoneware for my drip trays.   That way I know what the clay is and know what it will do.

 

Roberta



#4 JBaymore

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Posted 25 January 2014 - 11:20 PM

Wadding mix like that used for woodfire kilns. Fireclay based...... one of the cheapest raw materials.

 

Here's a recipe........... by volume ....... 2 parts APGreen Fireclay and 1 part sawdust.

 

Also use an extruder to make circular extrusions and build a frame that is like a big egg slicer to cut them into "cookies".

 

best,

 

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


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#5 Norm Stuart

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Posted 26 January 2014 - 12:31 AM

If we fire something that we know in advance will drip glaze, we fire it on a previously high-fired stoneware pancake or trays which were coated with our kiln wash Jeff Campana kiln wash - roughly half alumina hydrate and half kaolin - the same kiln wash we use on our shelves.

 

http://jeffcampana.c...ling-kiln-wash/

 

Because of the kiln wash the glaze normally easily slides off which extends their use.



#6 Biglou13

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Posted 26 January 2014 - 06:23 PM

What is plucking?

Sensei John..... I would need catch trays that are re useable multiple times. Every wadding I've seen is crumbly....

Thanks norm, It's pretty obvious the "inherited" kiln wash at studio is sub standard..... I suggested that today..........I think it fell on deaf ears ........ I'll just make some and donate it.........

Is calcined kaolin and glomax always interchangeable for this recipe?

To what temp or cone must kaolin be fired to to be calcined?

Anyone have lead on a kiln repair speckle?

Bcisk..... Had to make a clay... Non profit usually means no budget, I may do a kick starter for replacment kiln bricks and floor.

Had some small bags of raw materials this is what I made. Slurry technique. The recipe came from small amount of knowledge, but more so what was there.

5 gold art
5 #5
5 epk
5 xx
3 custer
3 grit 35-40

If you guys think this is a total fail let me know. I made it via slurry method it's drying and could probably add stuff if necessary.
It looked and felt exactly like someone else's recover slurry of Sylvia's raku. My thinking here was it was what was available in small quant. Gold art and. # 5 Are pretty much complete, plastic. epk refractory, saggar xx, hardy fire clay, custer a little,flux to,make,sure epk xx melt, grit for thermal shock, longevitty.
Caution big brother is watching.
The beige is blinding!!!!!!
The middle of the road is boring

The true sign of intelligence is not knowledge but imagination.
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#7 Norm Stuart

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Posted 26 January 2014 - 10:33 PM

The difference is Kaolin shrinks when fired, so too much in the kiln wash will lead to cracks as the kiln shelf doesn't shrink.

 

On the other hand calcined kaolin (Glomax) no longer acts like clay so it can't suspend itself in water or the other materials, so you need at least 10% kaolin.  Jeff Campana uses 25% kaolin, 25% Glomax and 50% Alumina hydrate.

 

At our studio I've changed this to 20% kaolin, 30% Glomax, 50% Alumina Hydrate and 1% Custer Feldspar to help it hold onto the shelf a little better.

 

You add Darvan and less water to either recipe so you can apply it like casting slip.  Some save very little money by using silica in place of alumina hydrate, but this saves a lot of labor cleaning glaze off shelves, especially in a wood fired kiln.

 

I purchase Glomax pre-made, so I've never calcined it.  They may need to regrind it after firing, I'm not sure.

 

If you don't want to purchase calcium phosphate cement, this is a light duty refractory.

 

http://cone6pots.nin...phosphoric-acid

 

But someone posted on these forums within the past couple of weeks a refractory cement they purchased at Home Depot.



#8 Norm Stuart

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Posted 27 January 2014 - 01:16 PM

I realize I originally said something without thinking enough in my previous post.  Kaolin only needs to be fired above the meta-kaolin conversion temperature of 1,050 to become something like Glomax which no longer shrinks.  So that would be as low as Cone 022 with a hold long enough at that temperature to transform all of it.  I'd probably fire a little hotter, maybe Cone 018?  But you have to experiment to be sure.  Unlike materials formed at higher temperatures, kaolin calcined at this temperature should still be free flowing so wouldn't need to be reground. I had originally mentioned a different cone which I've deleted so no one ever reads it and is misled by it.

 

Glomax is merely a brand name for a calcined kaolin - it's more costly but in a large studio with large discounts for clay material at Laguna, which is nearby, it's just easier paying $43 for a fifty pound bag which we'll eventually use rather than calcining a $16 bag of kaolin one pot at a time.  That would be a lot of my time handling kaolin with a respirator and firing containers of kaolin to to save $27 on a fifty pound bag.

 

Unlike other clay bodies, porcelain becomes a solid glass at maturity cone, so it becomes very soft and will tend to adhere to things it is touching unless they are extremely refractory.  When it does attach at places, this is called plucking.

 

What is plucking?

Sensei John..... I would need catch trays that are re useable multiple times. Every wadding I've seen is crumbly....

Thanks norm, It's pretty obvious the "inherited" kiln wash at studio is sub standard..... I suggested that today..........I think it fell on deaf ears ........ I'll just make some and donate it.........

Is calcined kaolin and glomax always interchangeable for this recipe?

To what temp or cone must kaolin be fired to to be calcined?

Anyone have lead on a kiln repair speckle?

Bcisk..... Had to make a clay... Non profit usually means no budget, I may do a kick starter for replacment kiln bricks and floor.

Had some small bags of raw materials this is what I made. Slurry technique. The recipe came from small amount of knowledge, but more so what was there.

5 gold art
5 #5
5 epk
5 xx
3 custer
3 grit 35-40

If you guys think this is a total fail let me know. I made it via slurry method it's drying and could probably add stuff if necessary.
It looked and felt exactly like someone else's recover slurry of Sylvia's raku. My thinking here was it was what was available in small quant. Gold art and. # 5 Are pretty much complete, plastic. epk refractory, saggar xx, hardy fire clay, custer a little,flux to,make,sure epk xx melt, grit for thermal shock, longevitty.



#9 Wyndham

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Posted 28 January 2014 - 11:48 AM

For small batches, I've put raw EPK in an old cracked bisk bowl  and fire with a bisk load, but as stated, it's cheaper to buy a bag of Glowmax.

Wyndham






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