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Cold Finish To Strengthen Ceramic


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#1 Isculpt

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Posted 11 September 2010 - 07:03 PM

I have been experimenting with making small tree branches from clay and paperclay. I use 1/8" to 1/4" branches from a contorta tree (also called "Old Man Walking Stick" because of its twisted, curled and multi-angled branch formation. I push wads of clay onto the limbs, covering them completely until the finished clay limb looks much like the original limb. Then I dry the clay limbs and fire them in an electric kiln. The branches burn out, leaving a narrow bore inside the ceramic branches. Unfortunately, while the branches look great, they're very fragile. I'm wondering if there isn't something that I can brush onto the ceramic branches after firing that will harden and make them less breakable. I remember reading about a product that was being used to hold concrete blocks together without mortar, simply by brushing it onto the surface of the blocks. Something like that is what I have in mind. Any suggestions???

#2 Chris Campbell

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Posted 12 September 2010 - 04:06 PM

Have you tried doing this by dipping the branches in slip multiple times?
I'm thinking that could build up a stronger surface.

Sorry ... Don't know anything about that cold finish.

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#3 Deb Evans

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Posted 12 September 2010 - 10:18 PM

isculpt
clay breaks - keeps us in buseness.
I've repaired a lot of fragile hollow ware also had a friend do large hollow spears ( 6ft)....always problems, always going to break. If you are committed to clay vers metal try pouring a plastic resin inside. IT WILL NOT protect braches from breaking but easier to repair because you will have a inside surface to work against.

#4 AmeriSwede

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Posted 13 September 2010 - 12:22 AM

isculpt
clay breaks - keeps us in buseness.
I've repaired a lot of fragile hollow ware also had a friend do large hollow spears ( 6ft)....always problems, always going to break. If you are committed to clay vers metal try pouring a plastic resin inside. IT WILL NOT protect braches from breaking but easier to repair because you will have a inside surface to work against.


That was my thought as well...Posted Image


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#5 Isculpt

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Posted 13 September 2010 - 09:27 PM


isculpt
clay breaks - keeps us in buseness.
I've repaired a lot of fragile hollow ware also had a friend do large hollow spears ( 6ft)....always problems, always going to break. If you are committed to clay vers metal try pouring a plastic resin inside. IT WILL NOT protect braches from breaking but easier to repair because you will have a inside surface to work against.


That was my thought as well...Posted Image


thanks for the suggestions...

#6 Marcia Selsor

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Posted 14 September 2010 - 08:46 AM

Cjris is right. Mkke some paper clay slip and dip your branches in that..building up layers of thickness. For a decent quantity you can get a bag of cellulose from the hardware store (blown -in insulation) and ad that to a clay body ...scraps soaked and blended into a slip consistency. Then ad the cellulose. Try for a mix of 15-25% cellulose to what you think your dry clay amount of the slip would be. Guesstimate volume.
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#7 JudyN-M

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Posted 14 September 2010 - 12:31 PM

The paper-clay is great for you when you are making the clay branches, but fired paper-clay is going to be the same strength or even less strong than regular clay. Since you are losing the branch surface when you cover it with clay or slip anyway, why not sculpt them out of paper-clay directly. You can start with a fuzzy yarn dipped in paper-clay slip which will be strong enough to hold the shape as you work on it. The fuzzy yarn strengthens the "branch" as you work on it and then burns out creating a matrix inside that retains strength. This is a trick I learned from a paper-clay workshop from Potters Council with Rosette Gault and Graham Hay. Or, better yet, why not incorporate those wonderful contorta branches into a mixed media piece with unfired paper-clay? See an example of one where I did just that in this community image which I just posted.

#8 Isculpt

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Posted 20 September 2010 - 11:21 PM

Cjris is right. Mkke some paper clay slip and dip your branches in that..building up layers of thickness. For a decent quantity you can get a bag of cellulose from the hardware store (blown -in insulation) and ad that to a clay body ...scraps soaked and blended into a slip consistency. Then ad the cellulose. Try for a mix of 15-25% cellulose to what you think your dry clay amount of the slip would be. Guesstimate volume.
Marcia


Thanks for the suggestions. I am using paperclay, both purchased and homemade, but I haven't tried using it as a slip...

#9 Isculpt

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Posted 20 September 2010 - 11:32 PM

The paper-clay is great for you when you are making the clay branches, but fired paper-clay is going to be the same strength or even less strong than regular clay. Since you are losing the branch surface when you cover it with clay or slip anyway, why not sculpt them out of paper-clay directly. You can start with a fuzzy yarn dipped in paper-clay slip which will be strong enough to hold the shape as you work on it. The fuzzy yarn strengthens the "branch" as you work on it and then burns out creating a matrix inside that retains strength. This is a trick I learned from a paper-clay workshop from Potters Council with Rosette Gault and Graham Hay. Or, better yet, why not incorporate those wonderful contorta branches into a mixed media piece with unfired paper-clay? See an example of one where I did just that in this community image which I just posted.


Thanks for all of your thoughts on the subject! I'm not sure I understand the difference between using a fuzzy yarn or the actual contorta branch in the finished piece, since they both leave a hollowed out interior. Thank you for sharing your mixed media piece. A sculptor friend calls me a "purist", but I want to create branches from clay rather than add real branches. I know the real ones are probably more durable, but I just like the idea of faux branches! The reason that I build around the contorta branch rather than sculpting the branches directly is that I like the four-directions twists and turns of the contorta, and I can't seem to get that exact look without a base to build on.




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