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fired plate pings


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#1 mnnaj

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Posted 29 May 2013 - 01:38 PM

I have a large-14" diameter earthenware plate that pings at least once or twice a day. It was bisqued at ^04, glazed with white majolica and overglaze, glaze fired to ^06. It is less than 1/2" thick. It was fired last December and has been pinging ever since. I have leaning against a wall with a plate rail under it.
My questions are - Will I wake up one morning to find it in pieces? Will the glaze pop off of it? If I refire to ^04 do you think that will stop the pinging?
Thanks
mnnaj
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#2 Chris Campbell

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Posted 29 May 2013 - 01:53 PM

What you have is a bad fit between the clay and the glaze. Think of a size 14 person jamming into size 8 jeans. It's gonna keep pinging because as the humidity and temp changes the plate and glaze will swell and shrink. Will it eventually fall apart .... Who knows? Re firing will not change the fact that the two things don't fit. Try another glaze or another clay next time ... Good luck!

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#3 trina

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Posted 29 May 2013 - 03:09 PM

Chris is totally correct, nothing can help the ping. I had a look at the picture, looks like you have a rather big craze or glaze fault along the bottom. You need to find a glaze that fits your clay. T

#4 Biglou13

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Posted 29 May 2013 - 04:22 PM

That's no craze. That's a full on crevice.

Work the clay to fit the glaze, or work the glaze to fit the clay.

Too bad I like the designs.

I've had my pots sing to me up to a week later. I like alitte craze.

Since December......your plate may be possessed..

I don't think , at this point anything will help. Other than crack it up and kintsugi repair it.
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#5 Pres

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Posted 29 May 2013 - 10:08 PM

That's no craze. That's a full on crevice.

Work the clay to fit the glaze, or work the glaze to fit the clay.

Too bad I like the designs.

I've had my pots sing to me up to a week later. I like alitte craze.

Since December......your plate may be possessed..

I don't think , at this point anything will help. Other than crack it up and kintsugi repair it.


One summer in graduate classes, I made over 150 pieces using school clay, school glazes from Penn State. End of the summer they came into the bedroom of our 3 room apartment. . . they stayed there for about 4-5 days, as the pinging every night kept us awake. Not thinking I moved most of them to the back porch. . . Funny how by the next year there was not one left. Occasionally I walk into a home with one of those old pots sitting in a prized area in the house. I don't say a word, but usually find the chance to look at the base signature. . . yes I signed them even back then.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#6 Mark C.

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Posted 30 May 2013 - 01:02 AM

Its a slow death thing-may take months or years but its terminal. When you ask will it go-well thats a wild guess thing.
refiring it can kill it sooner if that helps. You could cover the back with epoxy which may keep it ifrom falling but its coming apart sooner or later.
That crack is not helping and refiring will open that more.
Chris said it all in Her post about next time.
Ain't ceramics grand.
You could have fun and throw it like a Frisbee once.
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#7 TJR

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Posted 30 May 2013 - 09:12 AM

I was thinking about your dilemma. That plate is a goner. On the next one, try bisquing at cone 06, and glaze firing at cone 04. Your decoration looks great. Glaze looks a little thick. Go out to your concrete driveway. Hold the plate directly out in front of you, and have a friend kick it out of your hand so that it smashes on the cement. You will feel great. Time to move on.
TJR.

#8 Cyndi

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Posted 31 May 2013 - 07:13 AM

I have a long overdue question. What is the best way to learn the dynamics of clay/glaze fit.. Is it always as simple as low fire clay to low fire glazes as well as hi fire clay to hi fire glazes. Are some lo fire glazes compatible to hi fire clays? After 6/7 years of experimenting w/ it all on my own I really want to try and focus on the "right" way to get the best results. Thanks to all who contribute to this forum and have kept me hanging in there for this long. Luv it too much to give up.

#9 TJR

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Posted 31 May 2013 - 07:53 AM

I have a long overdue question. What is the best way to learn the dynamics of clay/glaze fit.. Is it always as simple as low fire clay to low fire glazes as well as hi fire clay to hi fire glazes. Are some lo fire glazes compatible to hi fire clays? After 6/7 years of experimenting w/ it all on my own I really want to try and focus on the "right" way to get the best results. Thanks to all who contribute to this forum and have kept me hanging in there for this long. Luv it too much to give up.


Cyndi;
You have bitten off a mouthful here.[is that a mixed metaphor?]I worked for years at trying to get a low-fire clear glaze to not craze.[add more flint]. I am now working on an ash glaze to stop the running. Great colour, but runs like 10 bears.[made that one up]. This is why we are all still in the game. If it was open a jar and paint on a glaze, I would have been done a long time ago.
Experts in the field are Val Cushing, Pete Pinnell, John Britt.And many more. Read, research and test. Then test again.
TJR.

#10 justanassembler

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Posted 31 May 2013 - 08:19 AM

I have a long overdue question. What is the best way to learn the dynamics of clay/glaze fit.. Is it always as simple as low fire clay to low fire glazes as well as hi fire clay to hi fire glazes. Are some lo fire glazes compatible to hi fire clays? After 6/7 years of experimenting w/ it all on my own I really want to try and focus on the "right" way to get the best results. Thanks to all who contribute to this forum and have kept me hanging in there for this long. Luv it too much to give up.


Cyndi,
Glaze fit isn't really what you describe there--though making sure that you are using a glaze that matures at the same firing temperature as your clay is a good starting point. Glaze fit has to do with the glaze's coefficient of expansion in relation to the clay... Crazing in its various forms is an indication that the fit is not good, different kinds of crazing can indicate how far from a good fit you are... Even if you're not firing at cone 6, the book mastering cone 6 glazes I think explains glaze fit (as well as other basic glaze formulation concepts) REALLY well for folks without an extensive technical background. The print version is out of print, however it is available as an ebook and you might luck out and find a copy at a clay supplier somewhere.

#11 Cyndi

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Posted 31 May 2013 - 06:55 PM

Thanks so much to both of you. Am searching for the book immediately. My goal is to do more researching and testing. I think part of my problem is I have almost every range and brand of glaze there is and about 5/6 different clays. I think simplification and focusing in on my main interest in what I want to achieve now is what i need to do. i was just wanting to try everything and anything. I do all methods also, but Joyce michaud's Asian coiling is my preference. Thanks again. Cyndi

#12 Jo-Ann

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Posted 31 May 2013 - 08:58 PM

Can pinging also happen if you take your pot out of the kiln before it cools? I have a year old pot from my first glaze fire in my own studio, took it out when it was still way too hot to be touching. (First glaze fire, I got inpatient ;) ) anyway, the glaze has tiny cracks all over it (I kinda like them tho) but I still hear it pinging anytime I am in my studio. After I took that pot out I closed the kiln and let the rest cool, none of the other pots did this so I thought it was the hot cold stress. . . Just curious now.

#13 LauraAnna

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Posted 05 June 2013 - 10:52 AM

Thanks so much to both of you. Am searching for the book immediately. My goal is to do more researching and testing. I think part of my problem is I have almost every range and brand of glaze there is and about 5/6 different clays. I think simplification and focusing in on my main interest in what I want to achieve now is what i need to do. i was just wanting to try everything and anything. I do all methods also, but Joyce michaud's Asian coiling is my preference. Thanks again. Cyndi


Depending on where you are, your local library may have a copy. I just read this thread and did the same thing - search for this book! And lo and behold my local library has 2 copies! So I requested one today. Amazon retails it for $190!! Library = Free. Best of luck




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