Need A Cheap Simple Clay Body Recipe

[Ben]

Look up an article called" body building for potters".

 

I see BOTH sides of this issue. I love using local resources and Harry Davis is A hero of mine But you have also been given some great advice and info about the pros and cons of making your own clay.

Ask this. "How much clay can i make in an hour vs how many dollars worth of pots in the same time?" I'm not trying to discourage you but the advice given against is valud and the cons stated are too. Worth considering.

 

That being said i agree with the idea that we should add to your stated goal of mixing a good clay and with that in mind...

 

The granite" dust" you have access to sounds like it is really granite sand and while chemically it is FAR superior and less variable than the other sand i think the particle size may be a bit large.

 

Have you done a sieve analysis on the granite to check the particle distribution?

 

I can't imagine throwing clay with grains that large.

 

Sounds like you also need to find a copy of Harry Davis book. "A Potters Alternative" an maybe start with the vibrating sieve project.

 

Good luck, keep testing the absorption, glaze fit, and shrinkage, and please keep us informed. Sounds like an interesting project to me. Im jealous. I live a long, long way from suitable fluxes for clay bodies.

[Matt Oz]

Doesn't this boil down to how much clay you use, if you're production potter and need tons at a time, than mixing your own is probably not the way to go, but a few hundred pounds at a time of your own clay body, not a big deal. Also if you mix your own clay, your able to mix it into a slip like Joseph is doing, it's a good way to go for quality clay. I have some of my own specialty clay bodies that have to mixed into a slip first.

 

As far as the dust hazard and my non expert opinion, if you mix up your own glazes as a lot of potters do, I would think you would be set up to handle at least smaller batches of clay.

[curt]

Hi Joseph any updates on your clay project?

[Joseph]

It has been a while but I was doing some research and found my own thread and thought I should give an update.

 

I have been using the 60/40 clay body + sand and talc for a few firings. I have been having vitrification issues in the cooler regions of my kiln. I've got a line on some free minspar and am thinking of adding some spar. I'm thinking of starting at 10% and leaving the rest of the formula alone. Any thoughts or comments would be appreciated. Thanks for all the advice

[Callie Beller Diesel]

Not a bad place to start. According to Insight, you up your flux and your silica levels, which theoretically should lead to more glass forming. Traditionally, Potash feldspars are used in clay bodies, I believe for reasons of thermal shock. The calculated expansion on the new recipe is higher, so watch your preheat. 

 

Just from poking around at the numbers on the computer, I'd do a couple test bars with 5% and 8% as well, as I think 10% might actually be pushing it.

[curt]

Talc is a good, but it is very refractory as fluxes go, meaning it will not melt well enough without some help to get decent vitrification.   You need the minspar and the K and Na it has to do the main fluxing work and then the Mg in the talc will add on.  See the nearby thread on stoneware fluxes for more discussion of such things.

[Guest JBaymore]

Another reason that potash feldspars are typically used in clay bodies is that the sodium in high soda spars and neph sy tend to be slightly soluble.  Over time in wet clay they can change the  water chemistry... and change the handling characteristics of the clay body...... going slightly thixotropic.  Some cone 6 bodies stored wet for a long time (fluxed with neph sy) are really prome to this issue.

 

I use "granite dust" all the time in bodies.  it runs anywhere from fines up to maybe 3/8" chunks.  For the nature of the work I do and the character I want in a body....... works just fine.

 

best,

 

...................john