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eoteceramics

Covering Up A Crack In Bisque

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I recently had a plate with 2 small cracks after bisque, not thickness, and wondered the same question.

 

I was hoping glaze would fill or at least minimize, which had been the case with a cup in the past. The end product resulted in two visible larger cracks with glaze on them.

 

The only other disguise I can think of if is kintsugi, and if not gold or silver then maybe enamel paint .

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I've had good luck with repairing bisque using magic mud (basically paper clay with sodium silicate and soda ash). There's a recipe at Lakeside Pottery. Obviously- should be made with the same clay as you bisqueware...

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I have found at times that a small crack that will probably get wider is easier to hide if you grind out the area a bit opening up the crack so that the glaze will work into the area more instead of just covering over the space. Work the first coat in with a stiff brush, and dip, spray, other coats.  This has worked about 75% of the time with student pots. O only used this when the crack did not appear "structural".

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I've had luck before filling small cracks with a combination of glaze and crushed bisqueware.

 

I'll usually take a trash piece of bisqueware, crunch it up finely (with a hammer, mortar+pestle, whatever), then mix it in with some thick glaze (either let some dry out or scrape it off the sides / top of the bucket).

 

Then I'll pack the mixture into the crack.

 

I haven't ever done it in the bottom of a water-holding vessel (I doubt it would be water-tight), just on cracked rims and joined pieces... But have had very good luck with it there.

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Thanks for replies, will try and get hold of mender friend,

 

Tried filling with glaze with no luck on a piece a while back,

 

Julia

Bath Potters (in the UK) do one for stoneware and porcelain if you're firing that high, (and more often than not they'll be cheaper than Potterycrafts).   I have no idea of its efficacy.

 

http://www.bathpotters.co.uk/high-fire-mender-2oz/p5369

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A lot of people seem to think (probably with good reason) that it is not worth the trouble to try and fill cracks because it will probably get worse and it is easier just to start over. Especially with higher-fired stuff such as stoneware or porcelein it is apparently more difficult.

However it is not a satisfying answer for something which took a lot of time & very hard work. I wish there was more technically-explained solutions that will work.

 

I will share the little information I have:

 

There is a product by Duncan called "Patch-A-Tatch".

"ceramic cement used to attach or repair greenware or bisque".

 

I know this works for attaching pieces that have broken off, e.g. handles etc, but I have not tried it for cracks. I think it is some kind of mixture that melts and fuses the two pieces together when fired. (Ceramic "Flux")

 

I have read about using the same phase of clay as in the original piece, e.g. if it is bisqued, then grind up bisque pieces and patch it (do not use raw clay to patch a bisqued thing). This makes sense to me because the shrinkage rates should be the same.

So it might be worth a try to mix pieces of ground bisque with e.g. Patch-A-Tatch or some kind of "flux" or paperclay slurry.

 

I know that paperclay has an amazing ability to attach to dry clay or even bisque. When it dries it does not shrink as much due to the paper fibres and it attaches better.

 

At the moment I am trying to fix a crack in greenware with paperclay. I have mixed the same type of clay with a bit of toilet paper to a slurry. Often people advise to mix in a bit of vinegar. The patch worked well but I still have to fire it. I fire only to earthenware temperatures so maybe I have a chance.

I will post the results in a week or two.

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Just to let those who might be interested know:

The crack mended beautifully. No sign of it after firing. (Earthenware).

It was a patch slurry made of paperclay and "Patch-A-Tatch".

So it was either the paperclay or the "Patch-A-Tatch" or both that did the magic.

 

 

A lot of people seem to think (probably with good reason) that it is not worth the trouble to try and fill cracks because it will probably get worse and it is easier just to start over. Especially with higher-fired stuff such as stoneware or porcelein it is apparently more difficult.

However it is not a satisfying answer for something which took a lot of time & very hard work. I wish there was more technically-explained solutions that will work.

 

I will share the little information I have:

 

There is a product by Duncan called "Patch-A-Tatch".

"ceramic cement used to attach or repair greenware or bisque".

 

I know this works for attaching pieces that have broken off, e.g. handles etc, but I have not tried it for cracks. I think it is some kind of mixture that melts and fuses the two pieces together when fired. (Ceramic "Flux")

 

I have read about using the same phase of clay as in the original piece, e.g. if it is bisqued, then grind up bisque pieces and patch it (do not use raw clay to patch a bisqued thing). This makes sense to me because the shrinkage rates should be the same.

So it might be worth a try to mix pieces of ground bisque with e.g. Patch-A-Tatch or some kind of "flux" or paperclay slurry.

 

I know that paperclay has an amazing ability to attach to dry clay or even bisque. When it dries it does not shrink as much due to the paper fibres and it attaches better.

 

At the moment I am trying to fix a crack in greenware with paperclay. I have mixed the same type of clay with a bit of toilet paper to a slurry. Often people advise to mix in a bit of vinegar. The patch worked well but I still have to fire it. I fire only to earthenware temperatures so maybe I have a chance.

I will post the results in a week or two.

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