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Pottery, Clay and Ceramics: What to do to fix Crummy Glaze?

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Anniesfollies
Carlsbad, CA
(Zone 10b)

November 27, 2012
6:45 PM

Post #9344231

Here's a picture of a cat I recently made showing the head where some of the glaze chipped off during the firing. I have a couple of questions about how to fix it.

1 - Why does glaze occasionally chip off in places when being fired? The instructor in my class says it's from being dirty, or I had oil on my hands, etc. I've had this happen a couple of times before and the one time I reglazed the chipped off sections it came off again, even though I made sure everything was clean. I'd like to fix this cat and am wondering what to do. I'm thinking I could sand it off a bit on the area where it came off using the white ceramic stone (forget what they're called) and then reapply. Any suggestions?

2 - I obviously don't like the way the purple or the blue glazes turned out. I was careful to apply three coats, although I have to admit I sometimes rush and am not sure the previous coats are completely dry. So do I need to sand it down lightly and then reapply, or just reapply a couple of coats making sure each is dry before adding the next?

Any help will be appreciated.
Annie


This message was edited Nov 27, 2012 8:10 PM

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mommacat11
Stafford, VA
(Zone 7a)

November 29, 2012
2:25 PM

Post #9345604

what cone were you firing and what cone did the glaze suggest?
Sometimes "Reds" do not play well with others and can be challengeing to fire.
If you can re-app;y that glaze and fire it again.. try that.
Deb
Anniesfollies
Carlsbad, CA
(Zone 10b)

November 29, 2012
6:06 PM

Post #9345755

It was fired in my class, I'm assuming at 06. The other color I had chip off was a medium burgundy and it did the same thing in the exact same place when reapplied and refired.

On the cat I want to reapply the blue and purple too, as they look very uneven and apparently I didn't get three thick coats on. I put too much time into the piece to toss it, but I wouldn't hang it as is.

You don't indicate that I need to sand any of it down before reapplying?
ItsMeChrissy
Union Grove, WI
(Zone 5b)

November 30, 2012
4:05 AM

Post #9346025

I don't sand when I do a refire/reglaze. But you should wait for the glaze to dry between coats and that takes a longer when glazing over fired glaze. You can try speeding up the drying with a hair dryer but don't dry too fast or it'll flake off.
mommacat11
Stafford, VA
(Zone 7a)

November 30, 2012
3:25 PM

Post #9346451

Is there some way you can look at the glaze bottle and see what shelf cone it was supposed to be fired at? Do you remember whichbrand it was?
Deb
Luvmypond
Troy, OH

December 4, 2012
2:46 AM

Post #9349302

Also, do you wipe off your piece with a damp cloth after the bisque firing before glazing? I've heard this helps the glaze stick.
mommacat11
Stafford, VA
(Zone 7a)

December 4, 2012
1:38 PM

Post #9349741

I always try to remember to wipe my pieces before I bisque fire them... Cleans them up nicely.

Deb
Anniesfollies
Carlsbad, CA
(Zone 10b)

December 5, 2012
6:39 PM

Post #9350874

Thanks for the responses. I do always wash my pieces before glazing because they sit outside on shelves when they come out of the kiln, and although they're under cover sometimes it's up to a week before I get to them. After I had the first piece have glaze chip off I've been very careful not to use any lotion on class days when I'll be glazing, so it shouldn't be that. As for glaze it was Mayco Firecracker and is and was fired at 06. I've used glaze from the same bottle several times and it's dependably beautiful, so it remains a mystery.

When I was teaching (4th grade) and did clay projects with my students I would occasionally have the same problem and sometimes have spots that would bubble and the glaze pop off in tiny 1/8" spots. I assumed it was the kids having dirty hands, etc. I guess maybe it's just something that happens occasionally.

I'm going wash my piece off, reglaze the red where it chipped and the blue and purple where the color is uneven and have it refired. Hopefully it will turn out okay.
Luvmypond
Troy, OH

December 6, 2012
2:08 AM

Post #9351071

It might not be a bad idea to sand it a little just to help the glaze stick better. Maybe it was something that was on the clay itself. Good luck and let us know if it turns out.
imapigeon
Gilroy (Sunset Z14), CA
(Zone 9a)

December 10, 2012
8:57 PM

Post #9355218

Sometimes glazes and clay bodies don't "fit" together. This means that the clay may shrink at a different rate from the glaze, which can cause the glaze to flake off. If reglazing and refiring don't work, you could paint with acrylic if it's not a functional piece.
bittsen
Portland, OR

January 5, 2013
9:28 PM

Post #9376817

My suggestion would be to glaze it with clear or white, fire it, then glaze it with the reds.
Yes, it's a pain but if you get one glaze to stick then the next glaze should stick to that.

palms29
Twentynine Palms Bas, CA

January 6, 2013
9:13 AM

Post #9377118

When refiring a glazed piece try wiping the piece off with rubbing alcohol before reglazing, this removes any oils. Sometimes warming a piece in the oven at very low heat, 100 to 130 degrees, warm to the touch but not too warm to handle will help the glaze stick.
Margo
imapigeon
Gilroy (Sunset Z14), CA
(Zone 9a)

January 6, 2013
11:52 AM

Post #9377268

I learned this year that putting a bit of hairspray on the area to be reglazed will help the new glaze stick!
mommacat11
Stafford, VA
(Zone 7a)

January 6, 2013
3:58 PM

Post #9377524

GREAT SUGGESTIONS!!!
Deb
Anniesfollies
Carlsbad, CA
(Zone 10b)

January 9, 2013
8:56 AM

Post #9379996

Thanks for more great suggestions!

I've been putting off reglazing this piece and have been tempted to just toss it, but you all have such great suggestions and I put too much time into it. Plus it's part of the set of cats I made to hang on the fence and it is kinda cute. I want to start the new year with all my old 'redo' and not yet glazed pieces out of the way so it's time to get out the Dremel and do some sanding.

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