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Weird water crystals


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#1 justin1287

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Posted 06 December 2012 - 03:32 AM

I looked at my glazed pieces in the kiln when it was at 400 degrees, and 2 of the pieces had water crystals growing out of the top. I turned the kiln off for an hour, took a nap, and they were still there. The kiln is at 600 degrees and they are still there. Is this normal? Maybe I usually just dont check on my work when its in the kiln.

#2 justin1287

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Posted 06 December 2012 - 03:43 AM

This is what it looks like at kiln temp of 800 degrees.

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#3 justin1287

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Posted 06 December 2012 - 03:47 AM

BTW.....it's just some commercial cone 6 glaze that i double dipped, and use all the time.

#4 Lucille Oka

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Posted 06 December 2012 - 04:26 AM

Justin there are no 'water crystals' (ice) that can survive at 400, 600, or 800 degrees. Water evaporates at 212 degrees F. and turns to steam.

What glaze is this? It looks to me like debris from the bottom of a glaze vat, or some of the crystals that can be found in glazes that have them in the mix. They also look deliberately placed and spaced.
The bits are quite large it's a wonder that you didn't see them when you applied the glaze.

John 3:16
"For God so loved the world that He gave His only begotten Son, that whosoever believeth in Him should not perish but have everlasting life".

#5 justin1287

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Posted 06 December 2012 - 04:45 AM

Lucille, it none of those.....As I said they just grew. They are a little bigger than course sea salt. This is a shino over a blue, and when i do this combination, the glaze tends to have pin holes in it before the fire (due to air bubbles), but they go away. Im wondering if the blue from the first dip is pushing some sort of molecule through the little holes. The kiln is at about 1200 degrees now, so i will see if anything weird happened soon when i open the kiln on thursday.

#6 JBaymore

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Posted 06 December 2012 - 10:29 AM

Is this a commercial glaze "shino"?

Looks like borax chunks or soda ash chunks (usually it fully dissolves in the glaze water and is evenly distributed).

Was the glaze seived through at least 80m before use? Had the glaze sat around a long time and had "dry stuff" possibly on the sides of the container?

best,

...............john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

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#7 justin1287

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Posted 06 December 2012 - 10:45 AM

went through a 60 mesh sieve........i shook it well, and only dipped down a little........1.5 month old glaze. may have made diamonds, jk. It's only 9 am here, and been up all night......time to throw more!

#8 Mark C.

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Posted 07 December 2012 - 02:27 AM

Not sure why one would look or care at 400 degrees but how did it look after going to cone 6? Was it normal looking then?
Looks like crystals but they are not from water at that temp. They most likely laid down at cone 6?
How is the piece after a normal fire?
Mark
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#9 justin1287

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Posted 07 December 2012 - 02:49 AM

They disappeared after a cone 6 fire.....I guess it is normal for my glaze.

#10 JBaymore

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Posted 07 December 2012 - 09:46 AM

They disappeared after a cone 6 fire.....I guess it is normal for my glaze.


On close examination there is absolutely no trace of a surface mottling or texture difference or anything like that which would indicate the location of those concentrations of a particular material?

best,

......................john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

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#11 TJR

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Posted 07 December 2012 - 09:49 AM

I think John is on to something with the soda ash material. I just mixed up a Cone 10 Shino glaze with soda ash in it. I put one third water in the bottom of the bucket and then dumped in all my materials for the glaze. I went to stir with my propeller. The glaze was crashing around the sides. I looked in. The soda ash had formed huge rocks like salt crystals. I removed the large chunks, reseived the glaze, but did not feel confident about using it with so much of one material removed. I had to remix the entire 10,000 gram batch. I tested both glazes .They look pretty much the same!
I guess the advice for you would be to smooth the surface with your thumb before you fire, and DON'T LOOK INTO THE KILN!
TJR

#12 JBaymore

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Posted 07 December 2012 - 11:49 AM

Soda ash is 100% soluble in water. But if it is the granular form, sometimes it is used before it dosolves. And sometimes the soda ash crystallizes out on the edges of the dry glaze on the container edges. Then it can fall back into the glaze on application... and cause concentrations of soda ash in localized areas.

But I would expect tehre tto be some trace of this concentration of the flux on the surface of the fired glaze.

best,


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



PS: BTW.... when I mix my main shino, all of the soda ash is first fully dissolved in hot water before adding that water into the overall wet glaze batch and stirred in. If you do this... be CAREFUL ... that concentrated soda ash/water solution is NOT good to get on your skin and particularly not good to splash in you eyes.
John Baymore
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Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#13 TJR

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Posted 07 December 2012 - 03:16 PM

Soda ash is 100% soluble in water. But if it is the granular form, sometimes it is used before it dosolves. And sometimes the soda ash crystallizes out on the edges of the dry glaze on the container edges. Then it can fall back into the glaze on application... and cause concentrations of soda ash in localized areas.

But I would expect tehre tto be some trace of this concentration of the flux on the surface of the fired glaze.

best,


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



PS: BTW.... when I mix my main shino, all of the soda ash is first fully dissolved in hot water before adding that water into the overall wet glaze batch and stirred in. If you do this... be CAREFUL ... that concentrated soda ash/water solution is NOT good to get on your skin and particularly not good to splash in you eyes.

John;
Thanks for the tip re hot water and soda ash. I did want to take a picture of the big rocks that it formed. Might be an old material. I always premix my bentonite before adding to the already wet glaze materials. I will remember to use hot water the next time I mix the Shino, and pre-mix the soda ash.
Tom[TJR]

#14 Mark C.

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Posted 07 December 2012 - 03:54 PM

TJR
What works great is a thrift store blender=mix the material and hot water in blender then screen into bucket-Its great for hard to screen materials-think glaze margarita.
Mark
Mark Cortright
www.liscomhillpottery.com

#15 justin1287

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Posted 22 December 2012 - 03:02 AM

ok.....so my brother used it a week ago, and it came out fine after the fire, but we could see crystals all over it before putting it in the fire, and he said it was hard to work with. So i decided to mix it up really good, then run it through a 60 mesh sieve. the problem is that only about 80% of the glaze is going through, and it is leaving behind a gritting mess that i have to scrape off. I'm really concerned that this is going to mess up the COE. Would it be better to not put it through the sieve and use it as is? Any other ideas? Help please!!!

#16 justin1287

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Posted 22 December 2012 - 03:58 AM

im attempting to boil the grit in water, and then going to sieve it into the mixture, then stir it up........hope it works cause this is going on 200 pieces tonight.




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