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Epic Failure - Glaze Looks Boiled Where It Meets Another Glaze


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I had my first WHOLE kiln load fail today. This has never happened to me before. I used a new glaze combination that I had tested and it worked fine on the test pieces but not today.

It is Amaco's HF Turquoise cone 6 and Coyotes cone 6 Sunset Pink.

 

The things to figure out...

 

Is the turquiose overfired? I am leaning towards overfired at this point but would like some input from you all. If overfired can I grind off the boiled rows and reglaze and refire at a lower cone? I realize this might affect the other glaze and all that but I am looking at it from a test to see what happens if I try it.

 

Are the turquoise and pink incompatible? If so why did it not do this on the test pieces?

 

Why does it look like its too thin ... That's 3 coats of glaze on there same as I did on the test pieces and yet it's practically vanished in spots.

 

Oh and I don't like failure and am not used to it so this is going to drive me crazy until I figure it out.

 

T

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Were your test pieces flat? I had this happen to me on a bowl where I tested two glazes when the top one ran over the other, then on a bowl in the bottom it bubbled. I dunno why but when the glazes ran it was pretty when it was flat it was terrible. Just an idea to start. I am sure the more advanced guys will chime in.

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so sorry!   the carved plate is great, though.  is it really so bad or is it only your perfectionist devil on your shoulder shaking a finger at it?  has anyone else who sees and touches it (not your husband) given a bad opinion?   in the end, it has to satisfy you, but maybe..........................

 

we know you don't value your husband's opinion.

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The husband said they were fine... But I don't feel comfortable selling something with the little boiled edges, if it gets a price tag it's got to be as perfect as I can get it. The glaze being a little thin is actually not too bad and looks kind of neat in a way and the piece doesn't feel rough like it has no glaze just the paler color in places. Oh and I do appreciate his opinion it just rarely matches mine OR what I want his opinion to be! Going on 33 years you would think he would have learned to react the way I want him to by now.

 

I will have to see if I still have any of the small pieces I did previously to show you all. I took a few to a show to see if they would be liked and they flew out of the booth. Should have taken a picture of them but I thought I like the way that looks and I can always make more. I am wondering if I placed them in a cooler spot in the kiln by luck (though I use cones on my shelves and they are really equal) OR this was a fairly light load maybe the pieces got hotter because there was less in there than usual?

 

The colors are turquoise and pink, think Art Deco color combination. The turquiose got 3 coats of glaze, I'm not dipping yet as I just started using this glaze so am still working out of the test pint I bought. I was worried that I had the glaze too thick and would get runs, but obviously not.

 

I am going to try grinding the boiled glaze lines smooth then put on another coat of glaze and fire everything again at cone 5. I'll wear my respirator and use my Dremel to carefully smooth that line down. I'll have to wax all those flowers again (ugh) and then put on another coat of glaze. If they turn out I know they won't be the same as if I got it right the first time but at least I will see what happens and if they can be rescued. If it works then I will need to find a cone 5 pink OR keep looking for a cone 6 food safe turquiose. I have tested 4 so far and no I am not up to mixing my own yet gang. One of them was not food safe and even though someone told me on the edges like that is ok I just don't feel comfortable using it so continued to search.

 

Here is an adjusted picture of the bottom, less orange and more pink. I took these with my cellphone so the colors are off some.

 

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So sorry about the glaze problem! Lovely pots, sad to see them less than perfect.

 

Are these blisters where the two glazes meet? Not sure but I think that is what I'm seeing in the first picture. I've never used commercial glazes so I'm no help with those you mentioned but I have had my share of blisters and there are lots of glaze, application plus firing conditions that can cause them. Have you read Jeff Zamek's article on blisters? there might be a clue in there.

 

http://www.ceramicindustry.com/articles/89054-diagnosing-glaze-blisters-part-4-glaze-conditions

(this is part 4, parts 1-3 linked on part 4)

 

I agree with you about filing them down, adding more glaze and firing again, at a slower rate and a little cooler.

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I know your awful feeling, Puggy. I had a catastrophic firing a few years ago that destroyed over $2000 worth of custom pieces...I had to make them all over again. I literally ran to the toilet and blarghed. Praise the kiln gods that has never happened since, but talk about a heart-wrencher. :( I hope you can recover your losses soon!

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Min - yes the blisters only appear along the edges, mostly where the 2 glazes meet. It also happens on the edges of spoon rests leaving parts of the edge pretty much bare clay. I didn't overlap they glazes at all in fact I went to great lengths to put the 2 glazes next to each other without any overlap which is why I am wondering if there is a compatibility issue between the 2. I am googling pictures of different blisters to see if I can find some that match mine.

 

Thank you for the article link a very useful read!

 

Guinea - thank you, at least this wasn't a special order or a hand painted load. How awful for you to have to recreate all that!

 

T

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This looks under fired to me, as well as too thin an application. Was the bisque a little over fired? That could cause the thinner turquoise application. The boiling at the edges - the copper in the turquoise is notorious for a little migration, in the hot atmosphere it is more volatile than most oxides - looks like it was apprehended mid-melt.

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I lean towards under fired to some degree, or maybe a little slower hold near temp to allow the boiling to release all gases, and resurface. There are some areas that look a little underglazed, but the problem with the boiling seems to be in the firing.

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