Intro/Porcelain question

[Min]

12 minutes ago, Sorcery said:

Dunno why..."B" says it all!

Started out as a recipe that was altered by Martin Butt. He had Laguna make it for him then when they started selling it to other potters the "Butts Mix" got abbreviated to B-Mix.

[liambesaw]

Well I can understand the abbreviation, kinda makes me giggle and I'm a full grown human

[liambesaw]

I think it's more expensive here because it has to be shipped up from southern california, no idea how cheap it is closer to the source.  We have a "sea-mix" here and it's no good for me.

[Mark_H]

That's a dramatic glaze difference Min.

[Mark C.]

1 hour ago, Min said:

Started out as a recipe that was altered by Martin Butt. He had Laguna make it for him then when they started selling it to other potters the "Butts Mix" got abbreviated to B-Mix.

Yes thats the true story

the rest is he owns and started Coyote Glazes

Factiod Monday

It throws well well the lips dry faster than the body and uneven drying is what it does so you need to work out those details

It also is made for wood fire (I have some for salting)

I used to make my larger wares from it but gave it up and just use porcelain now. Once you really learn a clay body and what can be done (for me its Daves porcealin) than the rest is easy.

[Marcia Selsor]

I throw porcelain and I use Coleman's Porcelain from Aardvark. It is a ^10 porcelain but  I use it for alternative firing processes. For ^6 porcelain I have been using Lindsay's, Archie Bray Porcelain for ^6 and recently I tried Plainsmen ^6 Ice. It is expensive but I may have to get more because it is translucent and I love carving it.

I learned large hand building from Bill Daley when I was in college. He built many large scale commissions using brickyard clay. World of difference from porcelain. He also fired his work at the brick yard on their conveyor kilns.  To work very large the clay needs to have grog which allows thick clay to shrink more evenly and avoid cracking. It avoids warping too.  Bill Daley http://www.williamdaley.net/about.html

 

If you look up Carlo Zauli for Faenza, you will see many large scale works glazed  white. The famous ceramics town, Faenza, is decorated with his large sculpture from the train station top downtown. Here are some examples.

 

[Marcia Selsor]

One of my other teachers, Paula Winokur used porcelain on a large scale but she added Molochite to it. That is a porcelain grog. https://sculpturemagazine.art/paula-winokur-formative-landscapes/

 

[Mark_H]

Very cool Marcia.

I've noticed all of Laguna's bodies that are for "large" application are listed as 'very coarse.' 

I was hoping to learn the nuances of one body, I don't know if adding grog to a porcelain body would cause it to behave like a completely different clay or not.   At which point  I might as well choose 2 bodies one for large format and then a nice smooth body for everything else.

I've also noticed 'small' 'medium' and 'large' are variable terms.  Large in my mind is Scott Semple's type of work:

[oldlady]

how does he fire that huge thing?   i  know there are potters who build a kiln around a pot to fire something that tall.   cannot imagine putting it into a top loader!  i noticed the kiln shelf under it.

[liambesaw]

2 minutes ago, oldlady said:

how does he fire that huge thing?   i  know there are potters who build a kiln around a pot to fire something that tall.   cannot imagine putting it into a top loader!  i noticed the kiln shelf under it.

You can fire in a top loader. You just have to take off the rings of your kiln, put that on the bottom of the kiln, and then stack rings on top until the whole thing is covered in rings.  I saw a video of someone doing exactly that!  It ended up being 2 top loaders stacked on top of eachother with a couple blank rings in the middle.  Is that worth doing? Well I guess some people think so, not me!

[oldlady]

thanks, liam.   i saw someone do that at NCECA.  as a demo it was fun, as a full time practice, a little different.  

[neilestrick]

54 minutes ago, liambesaw said:

You can fire in a top loader. You just have to take off the rings of your kiln, put that on the bottom of the kiln, and then stack rings on top until the whole thing is covered in rings.  I saw a video of someone doing exactly that!  It ended up being 2 top loaders stacked on top of eachother with a couple blank rings in the middle.  Is that worth doing? Well I guess some people think so, not me!

L&L makes their Jupiter series available as a pull-apart kiln, where each section plugs into a freestanding control box. They also do some big industrial kilns like that, too:

 

[liambesaw]

Holy guacamole look at that sucker

[neilestrick]

5 minutes ago, liambesaw said:

Holy guacamole look at that sucker

For those 7 foot tall pots we all make. 230 amps on single phase power! It probably runs on 480V 3P though.

[Mark C.]

Gas car kiln is way easier-Mine does about a 5 foot pot.

[glazenerd]

Mark H.

You are correct- course is a subjective term in pottery. There are several factors involved for determining suitable porcelain bodies. Translucent bodies like Coleman or Ice use Grolleg kaolin, or a blend of Grolleg and NZ kaolin. They also use premium plasticizers such as Bentone MA, and the flux levels are spiked to produce more glass. Kaolin can be fine mesh:-2 microns, or course 20-40 microns. Helmer kaolin for example is more suitable for large format bodies. Molochite as mentioned: likewise can be 325 mesh, of 50 mesh. The tradeoff being finer mesh to maintain functional properties, or larger mesh for non- functional use.

Porcelin is not a water friendly body: it has much lower tolerance than stoneware before folding occurs. Specs are generalized, and broad application terms applied. You can however make some judgments by shrinkage rates when given, High shrinkage rates (13.5-15%) indicate higher rates of plasticizer. Plasticizers absorb water, which translates to high shrinkage; which in turns means more prone to folding. Tile bodies have shrinkage rates from 10.5 to 12; and typically use larger mesh kaolin. While a bit tougher to throw: can handle larger forms.

Lastly, the piece you show was done in sections and attached after they had firmed up. 

Tom

[liambesaw]

48 minutes ago, glazenerd said:

Porcelin is not a water friendly body: it has much lower tolerance than stoneware before folding occurs

I was amazed to find that a freshly thrown porcelain piece was slaking from a slight drizzle outside.  Didn't realize you could slake down wet porcelain, it was really eye opening as far as how much water I use during throwing (which isn't a lot).

[neilestrick]

Porcelain takes in water quickly. You have to get it centered and pulled up quickly, and then you can take your time with shaping if you scrape the moisture off the exterior with a metal rib. It also gives up water quickly, so forms like wide bowls are always a struggle because the lip will dry so quickly compared to the middle. But if you need to speed dry something in the kiln, porcelain will dry out in half the time of a smooth white stoneware.

[Mark C.]

I find my work dries pretty evenly in a warm shop (no air moving much) as the pots are thrown on plaster bats so the base is sucking up water as the lips dry. I can pop the mugs off the bats ina few hours and spray with mister and cover and they even out for handles within about 30 minutes. We processed 210 mugs in the last three days and bisuqued them all on the 4th day (in kiln at 1200 now)None of the handles where cracked-all handles with even moisture then  covered one night then heat dried. The last 70  (1# mugs) got put right up into the heat without a nighly cover. If its eb=ven you can push them. Will glaze them in afternoon tomorrow. All done in 5 days from scratch to glaze firing.You can also load them in the kiln wet and take them up slow.I love the drying characteristics of Porcelain.

[liambesaw]

Doesn't matter what I use this time of year here, takes at least 48 hours to firm up enough to pop off bat, and another week or so to get bone dry.  Joys of outdoor potting in the PNW

[LeeU]

I'm just chiming in because it's about porcelain and I love the stuff---and I like it thick and heavy.  My favorite porcelain (no longer possible w/COVID and shipping expense) is a cone 6  called Cool Ice, distributed in the U.S. (from Australia) by Seattle Pottery.  It is terrific &  beautiful, especially when thrown and thin--but I just really like the paradoxical quality of going oppositional to thin/translucent/lightweight. This piece weighs over a pound & a half. Of course it is not big, and I wouldn't even begin to try!   (There is a cone  10/ Southern Ice).  I tried B-mix, just because I kept seeing it referenced in a positive manner, but (no disparagement intended) I just plain hated it--rubbery indeed!