Attaching Porcelain to Stoneware

[Callum Donovan-Grujicich]

Hello, I am working on a large sculpture, and in this sculpture I will be using coloured cone 6 porcelain to make a nerikomi pattern. The sculpture is a large hollow box, and I was thinking that I should add an internal support structure so the porcelain does not slump in the kiln. My question is this: because stoneware holds its shape better than porcelain, would it be possible to make the insides of the walls out of cone 6 stoneware and the outside out of the coloured cone 6 porcelain, and the internal support structure out of stoneware as well? My plan is for the walls to be 1cm thick, 5mm of porcelain and 5mm of stoneware. I have seen people mix stoneware with porcelain with no issues, does this also work for connecting slabs of the two different clays? I have attached a drawn diagram of what I am talking about.

Thank you,

Callum

[liambesaw]

Try it!  My initial thought is no, because they shrink differently and at different rates.  

Research architectural supports, a "grid" of stoneware won't be much more supportive than the porcelain itself.  I'd make either domed or triangle supports out of the same porcelain if you feel it's needed.  

Another thing you could do is used a grogged white stoneware body instead for extra structural integrity and not worry much about slumping.  

Is there a specific reason you need to use porcelain?  If it's for the look of it, you could always spray the entire thing with white slip.

[Callum Donovan-Grujicich]

18 minutes ago, liambesaw said:

Try it!  My initial thought is no, because they shrink differently and at different rates.  

Research architectural supports, a "grid" of stoneware won't be much more supportive than the porcelain itself.  I'd make either domed or triangle supports out of the same porcelain if you feel it's needed.  

Another thing you could do is used a grogged white stoneware body instead for extra structural integrity and not worry much about slumping.  

Is there a specific reason you need to use porcelain?  If it's for the look of it, you could always spray the entire thing with white slip.

Thanks for the help. I need to use porcelain because it fires the whitest and I am mixing mason stains into the porcelain, so I want the colours to stand out as much as possible. Besides, I have already mixed about $200 worth of different mason stains into the porcelain clay. The idea of supporting the sculpture with stoneware was only a secondary thought. The stoneware contains grog, so would it help if I used it as an inner wall and as a support structure?

With that being said, I do not want to add stoneware to the sculpture if that means the sculpture will likely crack, because the material costs of the sculpture are about $600 and I can’t afford to mess this up.

[liambesaw]

Make a test piece and fire it first if you're determined to go that route.  Make it to quarter or third scale to verify that it works.  Would be best to do this anyway if you need this to succeed the first time around.  

I have designs that I make that took 5 or 6 redesigns in order to find success, ceramics is not a straight forward, predictable process.

 

I'll add that with ceramics, sharp angles are not exactly an easy endeavor due to the way memory, joint strength and shrinkage work with the material.

[Callum Donovan-Grujicich]

10 minutes ago, liambesaw said:

Make a test piece and fire it first if you're determined to go that route.  Make it to quarter or third scale to verify that it works.  Would be best to do this anyway if you need this to succeed the first time around.  

I have designs that I make that took 5 or 6 redesigns in order to find success, ceramics is not a straight forward, predictable process.

 

I'll add that with ceramics, sharp angles are not exactly an easy endeavor due to the way memory, joint strength and shrinkage work with the material.

Good idea, thank you.

[Callie Beller Diesel]

You don’t have to use stoneware as an interior support. Just make it out of the same porcelain body, but without the mason stains. Then you’re not worrying about compatibility and shrinkage rates.