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How To Strengthen Delicate Ceramic Parts After Firing

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I've just broken the hands on a small sculpture and made and fired another pair of hands.  The problem is that a 3/4" long hand with slightly spread fingers is bound to be very fragile.  Can anyone recommend a penetrating glue or other substance that I can apply to these little hands to make them stronger?  They're made from Raku clay that fires from 06 to cone 6.  If I fire them to the higher end of the temperature range, will there be enough of an improvement in the strength to justify running the kiln for a pair of tiny hands? I can see that a pot fired to a higher temp would be stronger, I just don't know if it would matter with a hand that has fingers no thicker than 1/16-1/8"!

 

Jayne

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always make at least three of anything you are doing as a one-off. otherwise you are inviting disaster, plus you learna s you are producing multiples. A one-off is the concept of the buyer, we as makers should be making multiples to find the way and method to produce the best possible outcome, That said, there are a few epoxies that might work depending on what you finished product looks like.

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John, I can see the practicality of the "make three of anything done as a one-off", but the problem with that is that there are so many ideas and so little time!!!  Actually, you've given me something to think about.  As a sculptor, I tend to think that I "owe" it to the buyer not to make duplicates (even though, of course, they can't be exact duplicates unless I make a mold, and even then....). As I said, something to think about!

 

Is there an epoxy that you'd recommend?  I mix a five-minute epoxy for attaching small parts, but it doesn't really absorb very well.  I was wondering if there is something thinner bodied.

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I do not think the temp range on the tiny fingers will help-they are just fragile no matter what.

As far as epoxies go they all take up space-one the strongest is the regular JB wield as its runny for some time-the drawbacks is its  dark er and if you cut it after its dried its grey

If money is no object than west systems expoy is the way to go. Its in the boating trade and I use it on just about anything-its more clear and runny.

The thinnest but not the strongest is the cheap in-a stick crazy glue-I use it to glue my cut fingers a lot.Real thin stuff-goes off in 1-2 minutes.Dries clear- sold everywhere-$1.99-2.99

Mark

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Plus, if you make 3 for a custom order and only two live you have 2 for them to choose from, and it's an opportunity for them to think that they'd like the pair since they go so well together :)

 

you don't know if they'd buy multiples unless multiples are available...

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I'd also say make 2-3 of the item when possible, or if you know it's a problematic area. things that protrude from sculptures always want to break when you look at them wrong. I recommend that whenever you can, build something that comes apart/sectioned/modular so you can lift/transport it (large sculptures) or replace easily broken parts that protrude (ex: hands/fingers, horns, tails, leafs, rabbit ears, etc). How the piece comes apart/assembles is sometimes better than the actual object :)

 

Don't have a whole lot on strong runny epoxies. Maybe try PC Clear (I think that's what it is called). Made by the company that makes the awesome PC-7 and PC-11 epoxies (IMO the best consumer grade epoxy), but it's a clear that comes in syringe tube. I've never tried it myself so I can't comment on viscosity, but specs sheet shows it's way stronger than your average clear syringe epoxy.

 

There is also some liquid products for the hobby crowd (like plastic models/trains/rc) that a lot of people use to make clear windows/lenses. I believe it's fairly runny and makes a decently strong crystal clear product when cured. With a porous clay body, it might wick up into the clay.

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2 ton epoxy is stronger than 5 minute epoxy...i tested it. I use it to glue pin backs onto clay and the 5 minute epoxy i can pull the pin back off after it has cured...the 2 ton epoxy i cannot.

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Hello! Perhaps I can help.  I have some questions for you.

In this small hands how many fingers are separate?

What size is the grog in your clay, if any?

How did you fire it?

Did you use paper in your clay?

Did the hands were broken after fireing?

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Thanks for the names and labels, everybody.   I now have lots of epoxies and glues to check out, not only for strengthening, but also for attaching parts.  I've used the 5 minute epoxy, but haven't seen the 2 ton epoxy! 

 

John, if you look at my work, I think you'd have to agree that not many folks would say "Gee, I need TWO of those!"  Nonetheless, I've thought about your suggestion and I think it's a good one.  If nothing else, I can send one to a gallery and keep the other for the only show I do each year, the Piedmont Craftsmen Show in NC.  And to be honest, I always look at a finished piece and think "Hmmm, if only I'd......."  So if I follow your suggestion and make a couple at a time, I can try several sizes, proportions, colors, etc....

 

Angie, the fingers are spread as in a 'high five'.  Not that I make sculptures of folks throwing 'high fives' around....... !  I don't know the grog size in the clay.  It's Highwater Raku with a slight grog. I fired it to o6 to bisque and then to o6 after applying copper carbonate.  I didn't use paper in the clay.  For something that small, I don't usually like to use paper clay.  I find it hard to get fine detail, despite first soaking the shredded toilet paper and then adding it to fine dried clay that has been reconstituted, and then using a food processor to whip it into a fine slip before drying.  Yes, the hands broke after firing when the sculpture was knocked over.  I've ground away most of what was left of the hands, and now I have to get a really smooth surface to join the new hands to.  Anyone have a favorite grinding bit suggestion? 

 

An image of the sculpture sans hands is attached.  I could've gone with wing tips on the ends of the "arms" but human hands just seemed to work better with the stone textured, mountain referenced, human figure....  (what was I smoking, right?)

 

Jayne

post-1258-0-14732900-1403328676_thumb.jpg

post-1258-0-14732900-1403328676_thumb.jpg

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Funny you should ask-  (Anyone have a favorite grinding bit suggestion? )

I keep two dremel tools next to my bench grinder-one has a very small diamond bit the other has this silicon carbide bit that is less than 1/2 price now as a close out

I bought 12 last week-they are great for small work

http://www.amazon.com/gp/product/B00004UDKE/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1

You will need a 1/8 chuck in a dremel tool to use them

Mark

 

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Maybe a little future redesign of this sort of thing where the hands overlap the body in a wrist bent position. Another possibility is giving them a pose that strengthens them as curled in to a fist, or where one or two fingers grips the body covering and other fingers are hidden inside.

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Just to step back to the OP, firing a clay to the top end of it's maturity range will yield a stronger, more dense ceramic material. Might be worthwhile to make your smaller more fragile parts separately in clay (fire it all up to c6), and plan on gluing later, using any of the aforementioned epoxies. In the specific piece you posted an image of, it looks like this approach would be fairly natural. The pewter sounds of interest too though, good suggestions!

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Thank you all for a mind boggling array of ideas.  As for you, Babs, I can assure you that I do indeed have lots of problems.....and some of them are even ceramics related! ;) 

 

Jayne

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 Hello! Sorry for taking so long to answer. It is a pity that you have not decided to restore the hands.

You must take into account that now you will need to make an assembly. A rod and a hole must be enough.

You can make the hands with a modification of your clay or with other more resistant clay.

You can modify it with 10% transparent enamel and paper fiber or if you prefer cotton, no more than 5%. Or with fiberglass, which is hell to work with but harden’s the clay astonishingly well 0.5%.

Or switch to a high temperature clay, stone ware or some thing like that. You don’t have to fire it yourself, ask your local ceramic supplier they’ll know of someone that can fire it for a fee.

best wishes.

And for reinforce fired clay try  Elmer's glue.

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