Intro/Porcelain question

[Mark_H]

Hi, long time lurker, first time caller.  Started a college throwing night class last year and loved it, but fell short with Covid.  Additionally, have a buddy potter let's me use his studio prior to covid (see a pattern here?) I'm thinking about slowly assembling a studio, and wondering about clay bodies for wheel/handbuilding/large-scale

My question is about porcelain.  I loved the buttery-smoothness of the B-mix (which I hear is similar to porcelain but now read it's a cracky mess drying) but the folks I've met that throw big pots (5'-7' 200-400lbs) all use a real sandy (grogged?) stoneware body.  When I ask about throwing large scale porcelain, they say you can but a lot more 'failures/pots that don't come out' and I don't understand why.

I've seen the Chinese videos of 3 guys throwing massive porcelain pots, so It can be done, but I rarely see it, so there must be some reason.

1. Why do most large scale potters I've seen use stoneware rather than porcelain? 

Ideally, I'd like to use one body for all (perhaps with the addition of grog?) for everything, but maybe there is no such animal.

Thanks,

Mark

[Morgan]

Lot of variables to the questions you are asking but I will throw my .02 in. Keep in mind these are very broad reasons.

I think the bigger question you should be asking is what kind of results you want from throwing to glazing etc and match a clay body from there.

- porcelain is in general a bit more expensive

- in general is harder to throw super big thin walled pieces

- in general is a bit more finicky for beginners so failure rates is a thing (again depends on porcelain used and a ton of other factors but)

- is not as forgiving as many other clays

Thats just a few reasons. But then there are the reasons to use it. The texture, the way it takes glazes the list goes on. But ya if I was going to focus on massive say, planters for some reason, it probably makes zero sense to use porcelain.

bmix is one of the most popular clays because it has some, key word some, of the positives of both without being a true porcelain.  Also I have never heard bmix to have cracking problems if anything it is just an all around easy to work with clay body.
 

I for one have zero issues with failures or cracking with porcelain but that takes time and experience knowing the clay you work with. I make larger things with porcelain but I could probably do it twice as fast blind folded with some other clay, for me it’s worth it.

Again, I would look at your goals and what you enjoy making and start testing some popular clays and bmix sounds like one you already like...

[Callie Beller Diesel]

Hi and welcome!

One of the things that is interesting and challenging about clay is that most things are possible. Wether you want to put the work in to make it happen and how badly you want the end product are different matters entirely. 

I personally never had serious issues working with b-mix. (It also comes in a grogged version, btw.) I don’t like working with it because it’s weird an rubbery, but mine is likely an unpopular opinion on that, and since you got that opinion for free, it’s worth what you paid for it. 

Porcelain gets a bad rap among beginners because they’re still getting used to “listening” to their materials. Once you know what cues to look for, porcelain isn’t any harder to work with than any other clay, and working with it becomes second nature. But those huge pots you’re talking about aren’t beginner projects. 

One of the reasons stoneware clays  get used for those massive pots because stoneware has a wider variation of particle sizes that allow for greater structural integrity during both building and firing stages. It’s the same principle behind adding gravel and sand to concrete to make it stronger. Porcelain is more homogenous in its particle size, so while building a 7’ tall vase out of porcelain is likely not strictly impossible, it would probably be a heck of a lot harder. You’d be fighting a lot of physics to do it, and you’d have to modify almost every part of the working process to accommodate the material. You have to decide if this is where you want to spend your energy. 

Porcelains also contain more flux than stonewares do, which means porcelain is a lot more pyroplastic in the kiln, especially if you’re firing to maturity. When you’re taking about a 200lb mass of 1800* matter, there’s different firing considerations than there might be with a batch of 200 mugs.  

It should also be noted that porcelain from China is different than the commercially available porcelain here in North America, Australia, or anywhere in Europe. It comes from different mineral deposits, and it’s processed differently. In the case of those videos with the three guys throwing, I’m not certain whether fortune played a part in a natural clay forming  in that region that has the right combination of properties to allow that working style to evolve, or if it’s a custom blended material, or some combination of both of those things. 

[Bill Kielb]

My thoughts, all claybodies take some practice. Some are more difficult than others for throwing / hand building / large -scale coil building.

Folks generally use a body suitable for the task for which they find easy or pleasing to use. I have thrown many different bodies but prefer porcelain and always have. Is it more difficult to throw than Bmix, maybe, not for me Bmix seems too messy to me. But that’s just me. Not many folks build large scale 200 -400 # vessels and not many places can fire them. If you are planning to start your own studio, I would try and decide how best to interest the masses and go from there. When building stuff, maybe pick the most enjoyable body that works best for you and the shape you are building. Just about everything can be done with anything, I have used a dime as a screwdriver in a pinch. I still gravitate to a screwdriver though and now use a power driver or screw gun  more so these days.

[Mark_H]

Thank you.  I think my lack of experience adds to my confusion.

It sounds like using porcelain for 3/4-2" thick 5'-7' tall pots (or half wine barrel sized planters 36" diameter), while can be done, would have a lot more chance of failures/waste (on the wheel/kiln?) than a different clay body. 

So the right tool for that job would be a non-porcelain body, unless I wanted a high failure rate and few finished products for the work invested.  i.e. glutton for punishment, use porcelain for large format work.  Am I understanding this correctly?

And  the sand (which I dislike the feel of) adds to the structure which would make for easier large format work, which is likely why I see them using real toothy stuff for the giant pots.

 

[Bill Kielb]

I think that sums it up perfectly for you.
Behind all that common sense you may or may not choose to learn the science of it. Grog can help the clay fight gravity a bit better while throwing and firing and also provide a nice pathway for thicker bodies to dry more evenly. Fired porcelain may still end up stronger in some ways  though.  The cool thing about clay is there are an infinite number of things to learn and enjoy over a lifetime. Generally observing experienced potters do what they do will yield some realization of why they do it. It might be personal preference based on ease, experience, science, challenge, all of it or non of it.

[liambesaw]

I've been throwing for a long time, just recently took up porcelain again and I have structural problems and slumping with as little as 5 pounds of clay on the wheel.  Just now starting to get the hang of it, but it can be an expensive struggle, even for an experienced potter, to throw bigger with porcelain.  It's properties just don't really agree with being tall or heavy.

Threw this 5lb vase the other night and was so happy with myself that I did a little dance.

 

It's been a struggle for me to get tall and thin, but I'm finally rounding that corner.  I usually challenge myself once or twice every weekend with getting bigger, it's a fun break from mugs, bowls and plates.  But porcelain ain't cheap, neither is reclaiming, so the pile of porcelain screwups grows taller every week.  Part of the struggle i suppose.

It's also not just the throwing aspect that makes porcelain a pest either.  It is finicky with attachments, it needs to be even thickness as it dries, it sticks to unwashed shelves in firings, it has a tendency to warp in glaze firings...  But you cant deny it's beauty!

 

[Mark_H]

Appreciate the replies.  I assumed there was a reason I wasn't seeing a lot of giant porcelain stuff.

Thin, why thin porcelain?  Is porcelain not conducive to thick walled works also?

Yes, I find it borderline overwhelming what with : underglazes, glazes, resist, scratching, clay body variations, glaze chemistry,  degree of reduction, wood, soda, and now apparently body to types of work desired. 

I was hoping to find one body and a handful of glazes (I dig the shino, chun, celedon, temoku, oxblood stuff) and just focus on art and not chemistry, logging kilns, reading MSDS sheets ;)  perhaps that's unrealistic.  My background is building contracting so I'd just like to make stuff without data, paperwork, and code. :)

Good looking pot Liam!

[Min]

It's also common to throw large pieces thicker with porcelain than you would a like sized piece using stoneware then trim away a lot of the excess porcelain. I have friends who have spent time in Jingdezhen China, they do speak of the massive pots being thrown in sections and trimmed down. They have also said that studio potters are very rare; it's standard practice to do only one part of the process there. If you throw you only throw, you don't do brushwork decoration, you don't glaze and you probably don't fire your own kiln. You specialize in one part of the process then the pot moves on to the next person. If you spend your life just doing one thing I'm thinking you are going to get very good at it. (and more than a little bored probably)

To add to the confusion there is "porcelain" and then there is porcelain. There are quite a few "porcelain" recipes out there that contain ball clay, depending on your definition, a true porcelain contains zero ball clay. Reason this makes a difference is the ball clay makes the clay plastic whereas without it you are relying on only kaolin as the clay component of the recipe and it doesn't have anywhere near the plasticity of ball clays. Plasticizers such as bentonite or Bentone MA are added to aid in plasticity that they are lacking. There is a tradeoff, with zero ball clay porcelains you can get really white bodies, there isn't a ball clay that fires as white as the kaolins (or halloysite) used in porcelain bodies.

Throwing my 2 cents in here about B-mix also, I don't think it's anything like porcelain. It isn't translucent, it isn't white, it doesn't throw like any porcelain I've used, glazes don't sing on it like they do on porcelain, it's easy to throw really big pots with it. I find the cone 10 B-mix much nicer to work with than the cone 5. Are you planning on firing cone 10 reduction?

[liambesaw]

Only reason I'm happy about throwing porcelain thin is because it is extra difficult to control. It means my skills are growing.  You can make thick porcelain it is personal preference.  I make mostly functional items, so a thick heavy plate is difficult to carry and stack in your cupboard.  Trying to be considerate so my items are used every day.

[Callie Beller Diesel]

1 hour ago, Mark_H said:

I was hoping to find one body and a handful of glazes (I dig the shino, chun, celedon, temoku, oxblood stuff) and just focus on art and not chemistry, logging kilns, reading MSDS sheets

Ah, but the place where mastery of all the chemistry, kiln logs and science meets you're own giddy sense of "what if?" is where the art happens! Instead of thinking of these things as onerous, let your own curiosity and excitement guide your learning. It's sooooo much fun! Narrowing your field of study to one clay body and 5 glazes will still leave you with a lifetime of figuring out how they all work together.

[Sorcery]

2 hours ago, Mark_H said:

My background is building contracting so I'd just like to make stuff without data, paperwork, and code.

Oh, there is data, paperwork, and code!

The difference is that a building will always be a building of what is was made with, maybe they look better than imagined at sunset or sunrise, or a nice misty day, but it will always be more or less what it was meant to be.

A pot is worth the data, paperwork and code, because what comes out is always that next level of amazing, or at least can be if you wish.

I wouldn't reconsider Items that large at all, but do consider the outstanding logistical challenges from beginning to end. You'll need pallets of clay delivered, and should have your kiln door steps outside of your studio door. You'll be able to fill a small landfill with trimmings. Hell, you'll need a partner with every build, or an overhead crane!

What's your location?

Dig your own clay?

Optimal scenario would be you can dig infinite clay from your own land to fullfil an in-depth plunge into churning these things out with failure being as inexpensive as possible. Burning you own wood for fuel, blah blah..

That's why they are able to do such amazing things with that Porcelain. It's a "clay first" system, that utilizes many Techniques on one material to make many different styles of pieces.

Since your system is "product first", since your heart is set on going huge, you can utilize different clays and techniques that most easily creates your output. 

If that's porcelain, just go all in! I don't think there is a better way to learn. 

Are you going full industrial porcelain making?

Love this Guy. Some Inspiration!

 

Sorce

[Mark_H]

I see what you mean with experimentation even if only 5 glazes.  I read John Britts high fire glaze book and noticed iron in the clay body itself has a dramatic effect on the glazes. Perhaps a simplified data/record keeping system for the chronically disorganized

So thin porcelain displays one’s throwing prowess?

 

I’ve seen that video.  I like his glazing technique. Reminded me of Jackson Pollack.  
 

Not heart set. Id like a 10 or 20 huge things around the yard, (planters fountains) but with contractor’s back, knees, wrists, and elbows , it would be short lived and not an extended plan. Hopefully ‘normal sized’ functional ware, lamps.  It’s all hypothetical now, but I really miss throwing.  I’ve considered getting a wheel and a pugmill (contractor wrists) without a kiln and just making stuff and reclaiming it. 

Never digging my own clay, lifetime of shovelwork. I have Laguna and a clay manufacturer in Richmond, CA nearby  

Yes it would be cone 10 or 11  electricity is too costly in California. So, gas or wood.  If a hybrid bourrybox would work gas for heat, wood for ash. Anything more than a cord sounds unpleasant.  I even wondered if I could blow in buckets of ash similar to sodium to get unexpected atmospheric effects, but what do I know at this point.

 

[Callie Beller Diesel]

If you’re interested in making large wares but have joint and body issues, track down some Korean Onggi pot making videos. They have a slab/coil building method that’s kinder on the body and still badass. 

[Mark_H]

1 minute ago, Callie Beller Diesel said:

If you’re interested in making large wares but have joint and body issues, track down some Korean Onggi pot making videos. They have a slab/coil building method that’s kinder on the body and still badass. 

I've seen that.  The video above,  I think, is that style.

Body . . . I've helped my potter friend and I'm okay.  It was more just moose'ing the 300lb pots around, I wouldn't want to make a habit out of it at 50 (lifetime of moving heavy stuff.) 

He has two wheels and spins 18" - 24" high sections then we flipped them and stuck them onto the pot and wire them off of the upside down bat.  Then he torches again and sticks on more. 

This was stoneware, very gritty stuff.  On the bright side I should have access to a kiln for tall stuff, if I pitch in gas money.

You're right, there are workarounds that help, if a body wants it bad enough.  Pugger, stand up wheel, and cart kiln would be in my future.    As long as the wheel can reverse.  Apparently, I throw bassackwards (clockwise) which my instructor said something about Japanese wheels.  Lefty, and tried the regular way and couldn't make it work.

[Mark C.]

I work in porcelain. Its a tighter body than stonewares. it does not have the legs as stonewares. What are legs you may wonder. Legs are what some clays that throw well have -most stoneares have legs. B-Mix is white stoneware not porcelain. It has legs. Most stonewate have sand or grog or other fines that can make them throw well. I ordered a ton of Porcealin years ago that had fine white small grain grog in it to make larger pots so you can alter any clay body to do what you want.Most if not all porcelains do not throw as well as stonewares. I worked in stone ware for much of my life but stopped using it except for salt fireing in the later 80s. Since then my prodcution is all porcealain-Daves porcelain mostly but some 50/50 as well as Babu -all Laguna bodies.I like Daves as it throws better than most porcealin and has a better rate of non failure. Most porcelains are tighter bodies and will not be as forgiving as stonewares or any open clay body. 

If Tom will step in and explain this in detail it may help you understand better.

One thing I can say is one body for all work is like asking for a tire that fits all cars-just not going to happen.

I only have 50 years into clay so I'm still learning. In my next life I may master porcelain if I'm lucky

[Mark_H]

Very cool.  I didn't realize bodies could be altered to fit the purpose.

When you say "better rate of non-failure" is that on the wheel, or firing, or either?

I've not seen 50/50 at Laguna Website.  Is that #550 or 1/2 dave 1/2 Babu?

Now I realize I haven't used porcelain and comparing b-mix was errant.  I just liked how smooth and un-gritty it was.  I'll have to try some porcelain, now that I haven't tried it.  :)

Wow, 50 years.  Barring a medical miracle, I won't get to play with it that long, but I'll take what I can get with the time I have.

[neilestrick]

B-Mix and other smooth white stoneware bodies are nothing like porcelain. They are smooth, and whiter than brown bodies, but that's where the similarities end. White stoneware bodies are made primarily of ball clays, which a good porcelain will not have (yes, I'm a porcelain purity snob).

Working big with porcelain has a lot of potential issues. First, the shrinkage rate is higher, so you have to make things bigger to end up with the finished size you want. Second, it dries much faster, and fast drying is a problem with thick pieces because the walls won't dry evenly unless you dry them very, very slowly. Third, it doesn't hold shape as well as a groggy stoneware during forming. Fourth, it'll want to slump under its own weight in the glaze firing if it's too thin. Fifth, it absorbs water very quickly so you have to work quickly, which can be difficult if you're working large. Sixth, it has very poor dry strength so it's more difficult to move large pieces into the kiln.

All that said, you can make large pieces with it, but you have to know the material and understand its limitations and be willing to take longer to do them and accept a higher loss rate. I've done many 50 pound planters with a cone 6 grolleg porcelain (Standard 365) and they came out great. But it would have been a lot faster and easier to do them with stoneware. The thing is, there is no benefit to using porcelain for really large pieces. You're not going to make them thin enough to be translucent, so just throw them out of stoneware and cover them with porcelain slip if you want them to be white.

[Mark_H]

That explained everything I didn't understand and what people in person were unable to get across to me.  Thank you.

[Sorcery]

Porcelain is like the Inspector who cites you for BS, all of it.

Sorce

 

[Mark C.]

Yes 550 is what refered to as 50/50 my mistake.

Babu and 550 throw about the same (like cream cheese) Daves throws the best but is a slight bit  greyier in color. Neil sumed it up well above.

("better rate of non-failure" is that on the wheel, or firing, or either?) all of them

Daves does not glassify like other porcelains do.

If you are new to clay use stoneware-its easier-If you want big pots use stoneware its easier.

[Min]

17 hours ago, Mark_H said:

 I read John Britts high fire glaze book and noticed iron in the clay body itself has a dramatic effect on the glazes.

Yup, same liner glaze in both pots, porcelain on the left, b-mix on the right.

 

 

[Sorcery]

Lol, B-mix is the "poor man's" porcelain, so long as he is also blind.

Sorce

[liambesaw]

10 minutes ago, Sorcery said:

Lol, B-mix is the "poor man's" porcelain, so long as he is also blind.

Sorce

More like training wheels for porcelain.  It's more expensive than porcelain at my store

[Sorcery]

7 minutes ago, liambesaw said:

more expensive

Bogus! Too in demand.

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

Sorce