I have never read exactly what kind of clay is used, only that it is water-based and is supposed to dry along with the mache.

To tell the truth, I tend to wonder if there isn't some confusion about adding clay to papier mache that is due to some product names.

Creative Paperclay is a mix of volcanic ash, talc, water, starch, wood pulp and a preservative.  The only clay is in the name, which is something of a misnomer.

Paperclay, or P'Clay is a paper fiber/regular firing clay (all the usual types:  earthenware, stoneware, porcelain) combination.  Up to 25% of the mix is paper fiber that is well mixed into the clay, which is then formed and fired at high temperatures.  The paper burns out and leaves many fine pores, making the clay lighter than it would be without the paper fiber.

I don't know of any commercial papier mache that actually has clay in it, althought that is not to say that there isn't some out there somewhere.  Most of the commercial papier mache mixes seem to contain varying amounts of plaster.  I don't really consider that papier mache, but that is just my opinion.

My suggestion would be to try mixing wet pulped paper with different kinds of clay and see how it acts, and if it would be suitable for your purposes.

Everyone here would be interested to hear of any experiments of this nature.

Sue

I have tried mixing pulp with terra cotta, didn't fire it though... I tried to seal it using different kinds of paints and varnishes... made small bricks, painted or varnished them then left the bricks soaked on a basin of water overnight. First try, most of the bricks went soggy, others desintegrated... I tried greenfilms dissolved in high grade lacquer thinner and it worked!... I even left the test brick for 3 whole days and it's completely water tight. Greenfilms or maskcut films (red film) are used in textile printing as stencils.
The pulp is only around 10%, it tends to get lumpy if I add more to the terra cotta (red clay) and harder to model. I have also tried mixing pulp with plaster and pulp with cement. It took even longer to dry than my solid pulp pieces. The only plus side is it only requires a minimum of armatures compared to using only pulp. Pulp and plaster tends to be brittle and it drinks up paint and varnishes like a camel.
I suppose potter's clay could be terra cotta, earthenware or stoneware. You can improvise a kiln for terra cottas using a steel drum (oil drums) and charcoal as fuel... just curious, what sort of piece you would like to use pulp and clay for? >Eric

Many of the commercial 'papier maches' include plaster.  Celluclay is one of them.  It does limit your working time, however long it takes the plaster to set up.  Celluclay is the only one I've tried, and it was quite lumpy and not very cohesive.

The best adhesive I've found yet is methylcellulose.  You can buy it as wallpaper paste (such as Golden Harvest), but make sure that's specifically the kind you're getting.  They have vinyl types (never tried them, but everyone in PM seems to warn against them) and plain old flour/water types, which you could make at home.  Whatever kind you make needs to be fairly thin.  With the methylcellulose kinds, this is not a problem -- it works great thin.

Common Potter's Clay is just earthenware clay.

Sue