Repairing Small Crack In Bisque

[clayshapes 10]

I just took a large bowl out of the kiln from its bisque firing and discovered a small crack that runs about 2 inches from the rim down. Is there a way to repair bisque before glazing -- or is it a lost cause? I know the glaze will fuse the crack, but I think it will still be noticeable.

The bowl is made from cone 6 stoneware, that was bisqued to cone 04.

Thanks for any suggestions.

[jennifire 0]

I just took a large bowl out of the kiln from its bisque firing and discovered a small crack that runs about 2 inches from the rim down. Is there a way to repair bisque before glazing -- or is it a lost cause? I know the glaze will fuse the crack, but I think it will still be noticeable.

The bowl is made from cone 6 stoneware, that was bisqued to cone 04.

Thanks for any suggestions.

 

 

You could try making a little bit of paper clay to fill in the crack..... a little of your clay body + some wet toilet paper (30%-50%), throw it in a blender. After it dries see if you need to add more into the crack, dry again, sand to fit the curve of the rim. Glaze, fire. If you already have paper clay of the ^6, it would work too. Best of luck,

J

 

 

 

[clayshapes 10]

Thanks. Yet another new use for my blender. I'm going to try it. Curious though -- why paper? I've heard people say this before but don't understand what paper adds to the mix, from a technical point of view.

[clayshapes 10]

Thanks. Yet another new use for my blender. I'm going to try it. Curious though -- why paper? I've heard people say this before but don't understand what paper adds to the mix, from a technical point of view.

[bciskepottery 963]

You could try pulverizing a piece of bisque from the same clay body into a powder, mix it with some sodium silicate, and fill in the crack. Then, re-bisque the piece before glazing. The pulverized bisque will have already shrunk to the same condition as the bowl. If you add clay/paperclay to fill the crack in bisqueware and then go straight to glaze, the patch clay will not have shrunk and you will end up with a misfit.

 

There is a chance that the crack will continue to grow during the glaze firing; further, the crack will be weak point in the bowl and susceptible to cracking later. If the patch works, then use the bowl for decorative purposes.

 

By the time you make the patch, etc., you could have thrown a half-dozen replacement bowls -- none of which would have a crack. Personally, I'd toss it or use it as a bisque mold for hand-building.

[clayshapes 10]

Ha! You are right -- it will probably not work in the end and it certainly sounds easier to just make another bowl. Of course, no two bowls are alike. But I may try to repair it anyway, just in case there's a time in the future when something I can't replace cracks - and I will have had the practice.

Thanks for your help.

[Ria 0]

We take a dry piece of the same clay, pulverise it, add dogs hair to it and mix into a paste with brown vinegar. Then smear this micture into the crack and let it dry. bisque again and sand off the excess. Continue as normal.

This works. I have even used it to add a piece of a schulpture that broke off. Naturally it is weak after that, but it holds on.

Hope it works for others too.

[macdoodle 2]

Has anyone tried this product?

 

http://www.dickblick.com/products/amaco-bisque-fix/#reviews

[Pres 2,401]

 

 

Has anyone tried this product?

http://www.dickblick...ue-fix/#reviews

I have used it with kids in HS. It is about a 70/30 chance of fixing a piece. If it is a small piece that is not attached well, best bet. Cracks in objects are iffy, may take a second bisque and sanding. With the kids, they often didn't have the time/motivation to repeat the project so I used it. For myself I just rethrow the piece. In the long run it is less time consuming. If handbuilding it can come in handy for a repair where rebuilding would take much more time.

Over the years I have had to repair a lot of pots for students when something accidental happened. In one case, I reconstructed three pots when a display shelf dropped leaving me a bunch of broken pots. The job was completed with a lot of epoxy putty, and careful mix/match of acrylic paints to touch up the damaged areas. Pretty hard to find the damage in the end-and saved a few broken hearts. Yes, I did tell the kids what happened and apologized. I think in the end that they understood that it probably hurt me more than them.

[Marcia Selsor 1,905]

I always re-bisque a paperclay repair before glazing it.

It has a 90% chance or better of complete mending.

 

Marcia

[The Imperfect Potter 0]

I just took out a perfect cup but a small piece at the bottom broke on the inside leaving a little dent. How do I fix it if I can, Do I need to do anything before I glaze it? Or can I sand it down and glaze it

[Pres 2,401]

Sounds like a pop, from some contamination in the clay. Look closely(magnifying glass) see if there is any discoloring at center of dent. If not, check the piece that came out. You can glaze over the area after sanding and cleaning out the dust residue, but best bet is to make a new one.

 

best,

Pres

[CactusPots 245]

I've posted before about my adoration for paper slip repairs.  I never try to fix rim cracks.  Just not worth the time/kiln space.

[Mark C. 4,879]

Lip spits never heal -toss it and make another one.