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need help on glaze problem


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#1 Regina

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Posted 09 October 2012 - 03:08 PM

When I dipped a bisque fired bowl into glaze, the glaze cracked badly as it dried. It flaked off! Help! What is wrong with that glaze? Will anything fix it?

Thanks,
Regina

#2 Mark C.

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Posted 09 October 2012 - 03:17 PM

Was the glaze real thick?How long did you hold it in glaze?
You can wash your pot off with water and do it again quickly but first check to make sure the glaze is not like pudding.
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#3 neilestrick

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Posted 09 October 2012 - 03:27 PM

Could be too thick, could be a formula issue.
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#4 TJR

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Posted 09 October 2012 - 06:53 PM

Your glaze is WAY too thick. Wash your piece off, and let it dry overnight. Water your glaze down slightly, a cup at a time of water. Stir. Your glaze should look like cream, not yogurt.
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#5 bciskepottery

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Posted 09 October 2012 - 08:57 PM

When adding water to a bucket of glaze, add a little bit at a time, stir, and test . . . dip a test tile to see how thick the glaze covers. Repeat as necessary and use a new test tile. Sometimes, you don't need more water but a flocculant or deflocculant. Linda Arbuckle had a recent video on Ceramic Arts Daily about adjusting glazes . . . while she shows a majolica glaze, her techniques and advice applies to all glazes. Check it out. It is too easy to go from too thick to too thin. http://ceramicartsda...jolica-pottery/

If you are using community studio glazes, have the studio attendant add any water . . . do not do it yourself. Glaze thickness varies; our studio has an Antique White made with Gerstley Borate that is more spongy in consistency than the others. Some think it is too thick, when, in fact, it is at the right consistency.

#6 SmartsyArtsy

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Posted 10 October 2012 - 03:05 AM

Another caution: After you glaze the inside, let it dry before glazing the outside. If the pot is too wet from the inside glazing, it cannot absorb the glaze you apply on the outside.

#7 oldlady

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Posted 10 October 2012 - 07:35 PM

it might help to dip the bisque into a bucket of clean water QUICKLY and glaze it a few minutes later. this prevents so much of the glaze from being sucked into the very dry bisque piece you had before.
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#8 Pres

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Posted 11 October 2012 - 09:16 PM

it might help to dip the bisque into a bucket of clean water QUICKLY and glaze it a few minutes later. this prevents so much of the glaze from being sucked into the very dry bisque piece you had before.


Just a few thoughts here. First thing I always do is to wash my pots off with a damp sponge-removes any dust, and adds a bit of water to the bisqueware to cut absorption of glaze. I usually was pots in groups of 5-8. Next thing I would suggest is to check the thickness of the glaze before glazing-dip your hand into the glaze, and lift it out-you should have a coating that covers your hand evenly, but thinly-no color coming through-the cuticles and fingernail shapes should still show even though coated with glaze. The overall thickness of this glaze should be the thickness of a finger nail. If your glaze comes out too thick-then add water cup at a time until it is ready. Now, very important also is that you mix your glaze just before glazing to make certain that everything is in suspension, and continue to do so as you glaze. Hope this helps.

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#9 esh

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Posted 12 October 2012 - 07:37 AM


it might help to dip the bisque into a bucket of clean water QUICKLY and glaze it a few minutes later. this prevents so much of the glaze from being sucked into the very dry bisque piece you had before.


Just a few thoughts here. First thing I always do is to wash my pots off with a damp sponge-removes any dust, and adds a bit of water to the bisqueware to cut absorption of glaze. I usually was pots in groups of 5-8. Next thing I would suggest is to check the thickness of the glaze before glazing-dip your hand into the glaze, and lift it out-you should have a coating that covers your hand evenly, but thinly-no color coming through-the cuticles and fingernail shapes should still show even though coated with glaze. The overall thickness of this glaze should be the thickness of a finger nail. If your glaze comes out too thick-then add water cup at a time until it is ready. Now, very important also is that you mix your glaze just before glazing to make certain that everything is in suspension, and continue to do so as you glaze. Hope this helps.


Always thought that absorption of glaze is a good thing - let glaze and clay blend together under fire to produce a stronger pot and glazing - doesn't it?

#10 Pres

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Posted 13 October 2012 - 04:24 PM



it might help to dip the bisque into a bucket of clean water QUICKLY and glaze it a few minutes later. this prevents so much of the glaze from being sucked into the very dry bisque piece you had before.


Just a few thoughts here. First thing I always do is to wash my pots off with a damp sponge-removes any dust, and adds a bit of water to the bisqueware to cut absorption of glaze. I usually was pots in groups of 5-8. Next thing I would suggest is to check the thickness of the glaze before glazing-dip your hand into the glaze, and lift it out-you should have a coating that covers your hand evenly, but thinly-no color coming through-the cuticles and fingernail shapes should still show even though coated with glaze. The overall thickness of this glaze should be the thickness of a finger nail. If your glaze comes out too thick-then add water cup at a time until it is ready. Now, very important also is that you mix your glaze just before glazing to make certain that everything is in suspension, and continue to do so as you glaze. Hope this helps.


Always thought that absorption of glaze is a good thing - let glaze and clay blend together under fire to produce a stronger pot and glazing - doesn't it?


To some degree, but it is good to wash the pot to cut down on the thickness of a glaze coat. Washing the pot with a damp sponge before glazing also will remove any dust particles etc. that could cause crawling of the glaze. The washing puts a small amount of water into the pot and that water helps the glaze to be applied more evenly from the dipping process, and not to suck up so much water and glaze as when the pot is dry.

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


#11 Ben

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Posted 17 October 2012 - 07:21 AM

Do you have a gram scale (triple beam balance)?

If so you can test the water content of the glaze very simply and that is a repeatable, objective measurement that you can use to control your glazes.
You will need a cheap (about $5) 100 ml graduated cylinder and your scale. Cylinders are available online for very low prices, Not sure about forum rules for posting actual links to retailers.

weigh the empty cylinder and record the weight or adjust the scale to zero with the empty cylinder on it.
stir glaze well and fill with 100 ml of glaze, record the weight

since water is 1 gram per ml 100 ml of water should weight 100 grams.
your glaze sample should be more than this. Divide the sample weight by 100 to get the specific gravity.

if you weighed 147 grams your sample is 1.47 SG (water is 1.00 SG)

This will tell you how much water is in your glaze. I look for 1.35 as a mid point average for most glazes.

NOW, this doesn't mean that your glaze will behave properly at 1.35.It could use ingredients that thicken it (flocculants) or thin it (deffloculants)
IF your glaze has an average SG then you will probably need to adjust its flocculation to get it to apply properly.

Can you share the recipe with us?

#12 cf66

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Posted 05 January 2014 - 09:57 PM

I have the same problem, and I too think it's because the glaze may be too thick, although it has the consistency of buttermilk (thicker than milk, thinner than heavy cream). I'm afraid of adding too much water and ruining it (I have no dry glaze left).

 

Pres, can you please clarify the "no color coming through-the cuticles" part of your explanation? I think understanding this distinction might help me. I feel the adjustment in water content I need to make needs to be so carefully to avoid ruining the glaze!

 

 

Thank you...



#13 clay lover

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Posted 05 January 2014 - 11:15 PM

One thing I tell my students that have set up their own studio, When you dip your hand in the glaze and pull it out, does it look like you have a 'glaze glove' on? If so, it's too thick. If you can see the definition of the ends of your short nails, and the ends of the nail, at the cuticle in the glaze on your hand , that's more like it. If you see skin color showing , it's probably too thin, let it settle over night and remove a bit of clear water, stir and try again.

One question, how high are you bisquing to? If it's lower than that clay recommendations, it will be more porous and will absorb more glaze. The balance of how tight the bisque is, how thick the glaze is and how long you leave it in the bucket is a thing you have to work toward , no one can give you a formula that will answer this, you have to test, ask more questions and try again.
Don't be afraid to wash a thick glaze off, scrub the pot under the faucet if you want, let it dry overnight and try again.




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