[Clayart] white clay leaks.

Robert Harris robertgharris at gmail.com
Mon Jul 12 20:19:34 UTC 2021

I would add to Ron's comment that not all ancient porcelain was fired very
hot. According to Nigel Wood there seems to be good evidence that some were
fired in the region of 2250F, but held there for many many hours if not
days. (No doubt it is probably still "Cone 10", but due to heatWORK not
simply heat).

I'd also note that the Chinese themselves do not all accept the West's
definition of porcelain - particularly in terms of translucency or
vitrification. Many of the clay bodies (particularly the Northern Song
bodies) would refer to what we call a white porcelaneous stoneware. (e.g.
(I did a quick Google search and came up with these images for example):


On Mon, 12 Jul 2021 at 11:56, <ronroy at ca.inter.net> wrote:

> What Mel is saying here may lead some potters to think it is
> impossible to make a cone 6 white clay body that does not leak.
> I can do that, been doing it for 40 years. It's not impossible but you
> need to know what you are doing and keep an eye on any changes in the
> raw material.
> RR
> Quoting mel jacobson <melpots at mail.com>:
> > there is a very old saying.. porcelain is a white body, but, not all
> > white clay bodies are porcelain.
> >
> > one day we will go to a big show and the potter will be showing cone
> > 013 raku "ta dah" Porcelain...To even suggest
> > the word "Porcelain" would mean to me that the work is cone 10-12.
> > It is totally vitrified, and will hold
> > acid.   So much of what the vendors sell is "fluxed up" white clay
> > bodies and lets face it, no one really
> > cares if it is "almost vitrified"  I know, semantics
> >
> > That is why the clay I started using is brown, and totally
> > vitrified. you control the color, the redart
> > is the flux and makes it more workable.  I swear that in 2095
> > potters will be complaining their
> > cone 6 "porcelain leaks". hell, it is not even very close to "white
> > stoneware".
> >
> > I sat a tall tumbler out of mel 6 clay on Mike Meyers (MN Clay
> > owner) desk and filled it with water.
> > I said "keep it full for a month." he did.  not a drop of water on his
> desk.
> >  I boiled  bars of  clay for  3 hours
> > weighed them with a digital  scale.
> >   perfect.
> >   MEL
> >
> >
> > website: www.melpots.com
> > www.melpots.com/CLAYART.HTML
> >
> >
> Ron Roy
> ronroy at ca.inter.net
> Web page ronroy.net
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