Some of these ground stone pastes of mine are so short that even after 25 years of ageing. I still can’t kneed them by the usual spiral kneading technique. One is just so short that it cracks apart under the rolling stress. I return to the tried and true ‘cut and slap’ wedging method. This has be proven to me to work much better than spiral kneading where finely ground porcelain stone bodies are concerned. The cut and slap method compresses and activates all the clay particles that can respond to this kind of wedging. The rest of the fine, non-plastic stone particles are firmly encased in the weak plastic matrix. It develops a tight workable putty that is almost throwable on the wheel, as long as I take a lot of time to coax it along slowly into the final shape, without expecting anything to happen quickly. The essentially non-plastic, porous,  surface sucks up water and dries out very fast, making the whole soft and floppy, so I have developed a technique of re-using all the wet slip from my fingers to lubricate the paste, thick slip doesn’t absorb so quickly, so that it doesn’t become too floppy, and extends the working time. Still, I have to work fast to get the form into a suitable shape and lift it off the wheel before it collapses.

It’s clumsy and slow, but it eventually delivers a workable open bowl form. Very heavy at the base and only just thrown thinly enough at the rim to pass muster. I rely on doing a lot of turning to get the shape to emerge eventually from the clod of stone paste.

Turning can only be done on bodies like this when they are almost dry. Any time before this, the soft, loosely bonded coagulate of mineral granules, just tears itself apart into crumbly chunks, making the whole pot unusable. Australian readers will recognise this particular torn and crumbly texture if I mention the name of Mersey Valley cheddar cheese. It’s impossible to cut this cheese without it tearing and crumbling against the knife. My milled stone paste porcelain bodies act like this if I try to turn them leather hard. I wait until there are significant white drying rings all over the surface before attempting to start turning.

The stoney grit in the matrix takes the edge off the turning tools in minutes. I have to stop and file the edge on my hardened steel turning tools very regularly. This involves getting off the potters wheel and walking some distance away, where it is safe to create iron filings by filing the edge sharp again, that wont end up in the clay.

Since my last trip to Japan to study single stone porcelain making, I returned with a cluster of tungsten tipped turning tools specially made for turning porcelain. These tools stay sharpe for a very long time. But even they eventually go blunt under constant use. I have found that I can recover the cutting edge back to its pristine sharpness by using a diamond dust impregnated file. This is the closest that I get to bling! I do apparently own quite a few diamonds. It’s just that they are invisibly small and encased in some sort of amalgam. Not sexy, almost as expensive but very useful!