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Stoneware Continually "pings" Even After A Day...

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We just tried to fire a newly bought glaze that required 1160 degrees on stoneware that is labelled 1100 - 1280 degrees.

 

The kiln was opened at around 250 which we have done many times in the past. However, this time we heard several pinging sounds from the largest stoneware piece, so we immediately closed it until it got under 200. Then we propped open the lid with a brick until it got down to 100. All the time we heard the pinging sounds. At around 70 we removed all pieces and they were fine, except the largest one that kept "pinging" away. So we wrapped it up in a large piece of cloth and kept it like that overnight.

 

Today, almost 24 hours after it has gotten down to room temperature, it still "pings"!

 

Some bone china pieces did spontaneously shatter with a glaze from the same manufacturer, but that happened within minutes of them becoming room temp. This large piece has lasted way longer now. On another forum someone said we should tap it and see if it rings out like a bell or if it only produces a dull noise, which means it's internally cracked, but it does ring out like a bell still. We've heard that the glaze apparently isn't compatible with the stoneware, but does anyone know what we can expect? Will it spontaneously shatter a week from now, a month, a year?

 

EDIT: WRONG FORUM! My mistake. Can a moderator please move this to the "in the studio" forum? Thank you!

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Your glaze does not fit your clay body. The coefficient of expansion and contraction for the clays and the glaze is incompatible.Contact the glaze manufacturer and tell them. Maybe they can suggest a more compatible product.Or contact the clay manufacturer for suggestions as well.

 

Marcia

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look up the term "dunting"  

 

you have been given excellent answers to what the problem is.  your question is asking for an opinion, which is not fair to the person who "answers" it.  it is your decision about what to do with the piece.  i bet there are lots of beautiful pinging pieces on shelves in various studios to remind the maker not to do that again.

 

FYI your description of the temperature does not include either fahrenheit or celsius (centigrade) which would have been helpful.  the best answers come when the question has enough information.  you are in the right place in the forums.

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"We've heard that the glaze apparently isn't compatible with the stoneware, but does anyone know what we can expect? Will it spontaneously shatter a week from now, a month, a year?"""

 

I once heard a tale that a famous potter and glaze book author had a shirt made to wear to conferences. The front said "It's in the book". The back, "try it and see."

 

I think this is a back of the shirt type question.

You're just going to have to try it and see if it shatters. (It can, btw, happen months down the road. Happened to me)

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you are in the correct section of the forums.

 

look up "Dunting"

 

 Your question is not answerable since it requires someone to give you an opinion.  you are the only one who can decide what to do with what is essentially a defective piece.  i know there  are many lovely pieces sitting on studio shelves all over, quietly pinging and reminding the maker not to do that again.  if you like it, keep it.

 

the shirt was probably on Robin Hopper.  he has answered all the questions anyone could ask in the very long time he has been working with clay.  when he starts a workshop he tells people not to ask questions because the answers are all in one of his many books.

 

i had a much better, more gentle, answer but did not hit POST>

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It may fall apart sooner or later but more likely will just keep pinging for another week or so then slowly stop pinging. The misfit of glaze and clay compromises the strength, though, so it is likely to break more easily even if it doesn't fall apart.

 

Jim

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look up the term "dunting"  

 

you have been given excellent answers to what the problem is.  your question is asking for an opinion, which is not fair to the person who "answers" it.  it is your decision about what to do with the piece.  i bet there are lots of beautiful pinging pieces on shelves in various studios to remind the maker not to do that again.

 

FYI your description of the temperature does not include either fahrenheit or celsius (centigrade) which would have been helpful.  the best answers come when the question has enough information.  you are in the right place in the forums.

 

Good lord, Oldlady, he just asked if it would shatter!

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i went to a hockey game and a fight broke out or was that ....i went to a fight and a hockey game broke out, It's all my fault I had to mention ol' Bobby.

 

p.s nobody knows if or when it will shatter, you could just pretent its a crackle glaze....T

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bansell, my definition of dunting comes from John W Conrad's  STUDIO CERAMIC DICTIONARY   "a name given to a type of cracking caused either by rapid cooling or irregular cooling."    and goes on for 13 more lines.  

 

i did assume the post was referring to celsius.  what is the fahrenheit for 250 celsius?     482, way too hot to open.

 

your unkind additional comments were unnecessary.

trina likes this

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the definition of dunting in conrad's book includes a great description of how a piece looks if it is dunted.  the op says that other pieces have shattered.  

perhaps the poster  would like to know about dunting.  

 

giving info preceded by FYI is standard practice to just say "oh, by the way, it would help next time.........."

 

as to answering questions, i have asked repeatedly how to post pictures here. some people responded with very helpful information  but until atanzey posted info yesterday i did not get an answer to my exact problem. if i could have posted the pictures about various red glazes i would not have had to endure the endless pounding i have gotten since i posted the fact that red could be red if it isn't red.  if anyone reads the entire thing without prejudice it is clear that people read things differently and imagine all kinds of things that were NOT said.

 and nobody has told me exactly what i said that was so bad!!!  even though three people  ""LIKED"" the post.

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I believe this forum is dedicated to the exchange of information with respect.

So Trina ... What about the Great One huh?? I'll see two of your Orrs and raise you a Gretzky.

 

As to whether or not those pots will shatter ... Eventually and probably at the worst time possible.

Fresh from the dishwasher into the microwave .... Full to the brim with boiling hot stew .... On the buffet at Christmas with your evil relatives smirking... Holding the last serving of ice cream you were keeping secret from everyone .... In your best gallery during a meet the artist evening ....

 

You know they are defective so any decision to sell them is probably not wise ... Especially since your knowledge of the defect is online right here.

Patsu likes this

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So Trina ... What about the Great One huh?? I'll see two of your Orrs and raise you a Gretzky.

 

This reminds me, when my mother was a little girl growing up in the Detroit area, Her older sister would take her to hockey games, coming out of the arena one night she all of a sudden got caught up in a large crowd and didn't know what was going on, until she looked up at who was walking beside her Mr. Hockey himself Gordie Howe. Of course he was very nice about the hole thing.

trina likes this

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So Trina ... What about the Great One huh?? I'll see two of your Orrs and raise you a Gretzky.

 

 

This reminds me, when my mother was a little girl growing up in the Detroit area, Her older sister would take her to hockey games, coming out of the arena one night she all of a sudden got caught up in a large crowd and didn't know what was going on, until she looked up at who was walking beside her Mr. Hockey himself Gordie Howe. Of course he was very nice about the hole thing.

 

 

ah gordie, now that was hockey! you made my day :) T

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As to whether or not those pots will shatter ... Eventually and probably at the worst time possible.

I'm not so sure. I've had pots ping on for days and days after firing, especially when I was salt-glazing, and testing liner glazes. I've never had a single pot shatter (once cooled and out of the kiln).

 

It seems likely that the pinging is due to crazing - that's normally the case, I believe. This certainly means the pots won't be as strong as they might be, given that the glaze won't be doing so very much in the way of compressing the body. But if they still 'ring' - and OP said they did - then I would rate their chances as better than good.

 

Something else - OP has fired to 1160 deg C, on a body that claims to fire from 1100 to 1280 deg C. I would guess that 1160 has not fired that clay to proper - optimum - maturity. So again, not so strong. But I still think it won't spontaneously shatter.

 

And I know nothing at all about hockey, except that when I played at school (not on ice, but on grass), the ball seemed jolly solid, and getting out of the way of it seemed advisable at all times.

 

 

Sounds like craze pinging to me too. The pots that shattered where a different clay body, bone china.

 

In the old days ice hockey goalies did not wear a mask.

Terry Sawchuk

sawchuk_display_image.jpg?1284757653

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Yikes! I knew the teeth were gone early but that face proves you had to be somewhat 'crazed' to be the goalie ... and they fought the mask and helmet rules ... and they made diddly ... had to work off season jobs to pay the rent. Ah, the good old days!

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obet,

 

Fresh crackle in a glaze can be hard to spot. Try rubbing some indian ink over the glaze, and

any crackle will show up clearly. [if the glaze isn't crackled, then you can just wash the ink off.]

 

Regards, Peter

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Thank you for all of your answers! It was not my intention to try to stir up anything.

 

I guess we will just have to wait and see (and pray). :)

 

We have noticed the forming of ever so faint crazing on the glaze though (day three of pinging now), but the stoneware itself is quite thick, so hopefully it will just be a cosmetic issue and we will leave this as an experiment and order our next slip from the same manufacturer as the glaze (after we've called to double check of course).

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