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Cleaning kiln shelf


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#1 cracked pot

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Posted 26 January 2013 - 03:52 PM

I have never had any formal training kiln use and have always been very careful with applying my glazes to avoid glaze drips. Most drips, if they occur are easily scrapped off because of the kiln wash. However, I did just have a glaze drip on one of my kiln shelves, small, but it ate through the kiln wash and went into the shelf itself. I have tried grinding it down with small grinding bits and now have a one inch long shallow groove in the shelf that still has some glaze in it. My question is, can I just leave it alone, re-do the kiln wash and avoid this spot in future firings? Will the glaze drip continue to eat through the shelf? Seems like a goofy question but I have never seen this addressed on the forums before.
Thanks

#2 neilestrick

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Posted 26 January 2013 - 06:02 PM

Glob some wash on it every firing and in a few firings it will be sealed up with wash and you can put pots there again.
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#3 R Fraser

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Posted 26 January 2013 - 06:14 PM

I am glad you asked this because I had the same odd thing recently. Usually glaze drips chip off easily but one glaze seemed to actually incorporate the alumina hydrate wash and flux right into the surface of the corderite shelf. I just ground it flat with an angle grinder more or less to the surface surrounding the defect and re-coated with kiln wash. It does not seem to have gotten any deeper in subsequent firings but it is weird. Will be interested to hear what others have to say.
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#4 OffCenter

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Posted 26 January 2013 - 07:01 PM

I have never had any formal training kiln use and have always been very careful with applying my glazes to avoid glaze drips. Most drips, if they occur are easily scrapped off because of the kiln wash. However, I did just have a glaze drip on one of my kiln shelves, small, but it ate through the kiln wash and went into the shelf itself. I have tried grinding it down with small grinding bits and now have a one inch long shallow groove in the shelf that still has some glaze in it. My question is, can I just leave it alone, re-do the kiln wash and avoid this spot in future firings? Will the glaze drip continue to eat through the shelf? Seems like a goofy question but I have never seen this addressed on the forums before.
Thanks


Just curious, did the glaze have a lot of copper in it? Just do what they suggest above and the shelf will probably be alright but if it is copper there is a slim chance that it will eat a little further into the shelf. If there is still a lot of glaze in grove, I'd turn the shelf so that the side with the glaze on it is facing down for the next firing or two.

Jim
E pur si muove.

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#5 cracked pot

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Posted 26 January 2013 - 07:42 PM


I have never had any formal training kiln use and have always been very careful with applying my glazes to avoid glaze drips. Most drips, if they occur are easily scrapped off because of the kiln wash. However, I did just have a glaze drip on one of my kiln shelves, small, but it ate through the kiln wash and went into the shelf itself. I have tried grinding it down with small grinding bits and now have a one inch long shallow groove in the shelf that still has some glaze in it. My question is, can I just leave it alone, re-do the kiln wash and avoid this spot in future firings? Will the glaze drip continue to eat through the shelf? Seems like a goofy question but I have never seen this addressed on the forums before.
Thanks


Just curious, did the glaze have a lot of copper in it? Just do what they suggest above and the shelf will probably be alright but if it is copper there is a slim chance that it will eat a little further into the shelf. If there is still a lot of glaze in grove, I'd turn the shelf so that the side with the glaze on it is facing down for the next firing or two.

Jim


Thanks everyone for your advise.
Jim, I don't know if there is copper in the glaze. It was Potter's Choice, Ancient Jasper. The glaze has to be put on thick to get the beautiful red tones. I never had a problem before with it, but this time I used it on mugs and it slid right down the handles.
If I turn the shelf upside down, is there a chance that the glaze would drip onto the one below?

#6 OffCenter

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Posted 26 January 2013 - 10:54 PM



I have never had any formal training kiln use and have always been very careful with applying my glazes to avoid glaze drips. Most drips, if they occur are easily scrapped off because of the kiln wash. However, I did just have a glaze drip on one of my kiln shelves, small, but it ate through the kiln wash and went into the shelf itself. I have tried grinding it down with small grinding bits and now have a one inch long shallow groove in the shelf that still has some glaze in it. My question is, can I just leave it alone, re-do the kiln wash and avoid this spot in future firings? Will the glaze drip continue to eat through the shelf? Seems like a goofy question but I have never seen this addressed on the forums before.
Thanks


Just curious, did the glaze have a lot of copper in it? Just do what they suggest above and the shelf will probably be alright but if it is copper there is a slim chance that it will eat a little further into the shelf. If there is still a lot of glaze in grove, I'd turn the shelf so that the side with the glaze on it is facing down for the next firing or two.

Jim


Thanks everyone for your advise.
Jim, I don't know if there is copper in the glaze. It was Potter's Choice, Ancient Jasper. The glaze has to be put on thick to get the beautiful red tones. I never had a problem before with it, but this time I used it on mugs and it slid right down the handles.
If I turn the shelf upside down, is there a chance that the glaze would drip onto the one below?


My guess is that Ancient Jasper doesn't have a lot of copper so I don't think it will burn any deeper into the shelf. Yes, there is a chance the glaze could drip onto the one below but that could be a good thing in that it is a way to get rid of some of the glaze on the shelf without more grinding and damage to the shelf. Obviously, you'd put something beneath it to catch any drips. But, I'd only do that if there is a lot of glaze still there than can't be knocked off with a grinder. Probably your best bet is to ignore everything I've said and just slap some kiln wash on it.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#7 cracked pot

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Posted 27 January 2013 - 09:15 AM




I have never had any formal training kiln use and have always been very careful with applying my glazes to avoid glaze drips. Most drips, if they occur are easily scrapped off because of the kiln wash. However, I did just have a glaze drip on one of my kiln shelves, small, but it ate through the kiln wash and went into the shelf itself. I have tried grinding it down with small grinding bits and now have a one inch long shallow groove in the shelf that still has some glaze in it. My question is, can I just leave it alone, re-do the kiln wash and avoid this spot in future firings? Will the glaze drip continue to eat through the shelf? Seems like a goofy question but I have never seen this addressed on the forums before.
Thanks


Just curious, did the glaze have a lot of copper in it? Just do what they suggest above and the shelf will probably be alright but if it is copper there is a slim chance that it will eat a little further into the shelf. If there is still a lot of glaze in grove, I'd turn the shelf so that the side with the glaze on it is facing down for the next firing or two.

Jim


Thanks everyone for your advise.
Jim, I don't know if there is copper in the glaze. It was Potter's Choice, Ancient Jasper. The glaze has to be put on thick to get the beautiful red tones. I never had a problem before with it, but this time I used it on mugs and it slid right down the handles.
If I turn the shelf upside down, is there a chance that the glaze would drip onto the one below?


My guess is that Ancient Jasper doesn't have a lot of copper so I don't think it will burn any deeper into the shelf. Yes, there is a chance the glaze could drip onto the one below but that could be a good thing in that it is a way to get rid of some of the glaze on the shelf without more grinding and damage to the shelf. Obviously, you'd put something beneath it to catch any drips. But, I'd only do that if there is a lot of glaze still there than can't be knocked off with a grinder. Probably your best bet is to ignore everything I've said and just slap some kiln wash on it.

Jim


Thanks Jim

#8 minspargal

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Posted 27 January 2013 - 09:22 AM

Once when i was in college, one of the students used a glazed and low fire clay and fired the gas kiln to cone 10. The next day when the kiln was opened you could see how that clay had melted and burned thru the shelves like an acid. The professor was not too happy.

#9 Benzine

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Posted 27 January 2013 - 10:04 AM

Once when i was in college, one of the students used a glazed and low fire clay and fired the gas kiln to cone 10. The next day when the kiln was opened you could see how that clay had melted and burned thru the shelves like an acid. The professor was not too happy.


Whoa, really? Through the shelf?

In college, one of my classmates brought in some blue green, found clay, and our instructor let her fire it. In the bisque, it was fine, and turned a nice, golden yellow. For the glaze firing, he had her put it inside a larger, stoneware vessel, just in case. And at full temperature, which I think was between Cone 6 and 8, the found clay, did indeed melt. It didn't melt completely, but deformed greatly, and became "glassy".
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#10 Claypple

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Posted 27 January 2013 - 07:12 PM

Gee! Good to know about all this trouble.
When my kiln arrives (I am buying it from Neil), I better start using unglazed "saucers" (or should I say "coasters"?)
to catch the drips. Just cover it with the wash first. Would it save the wash too?




#11 Lucille Oka

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Posted 27 January 2013 - 09:44 PM

My goodness that Ancient Jasper is beautiful. One thing I learned about glazing ware using the Potter's Choice glazes is not to talk to anyone, it is too easy to lose count of the coats when applying the glaze; especially when brushing it on.
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#12 minspargal

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Posted 28 January 2013 - 08:40 AM


Once when i was in college, one of the students used a glazed and low fire clay and fired the gas kiln to cone 10. The next day when the kiln was opened you could see how that clay had melted and burned thru the shelves like an acid. The professor was not too happy.


Whoa, really? Through the shelf?

In college, one of my classmates brought in some blue green, found clay, and our instructor let her fire it. In the bisque, it was fine, and turned a nice, golden yellow. For the glaze firing, he had her put it inside a larger, stoneware vessel, just in case. And at full temperature, which I think was between Cone 6 and 8, the found clay, did indeed melt. It didn't melt completely, but deformed greatly, and became "glassy".


It was an ugly mess and it did act like an acid, and yes we were surprised to see low low fire clay and glaze could do that to high fire shelves.

#13 cracked pot

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Posted 28 January 2013 - 09:50 AM

My goodness that Ancient Jasper is beautiful. One thing I learned about glazing ware using the Potter's Choice glazes is not to talk to anyone, it is too easy to lose count of the coats when applying the glaze; especially when brushing it on.


Lucille,

You're right, it's easy to get over enthusiastic in trying to get the desired result. I have never had a problem before but this time I really wanted the variation in color to be great so I went a little heavy. You can just see the glaze run under the handle of one of the mugs. Still amazed at how it ate through the shelf!

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