Incredible Mother Nature’s porcelain

This is made from 100% of a natural clay (3B) from the Whitemud formation in Ravenscrag, Saskatchewan. To make this body, which I call MNP, I slake and slurry up the raw clay lumps, sieve it to 200 mesh and then dewater on a plaster table. I rolled the plastic clay into a thin layer, cut it into a cross-shape using a 3D printed cookie-cutter, drape-molded it over a plaster form and then slip-joined the seams. It fires very dense and strong (to zero porosity like glass!). It holds together well and joins well with its own slip. Although not super plastic, it is smooth and fine-grained like a commercial porcelain body. I add 1-2% bentonite to make it more plastic when needed. It can be rolled extremely thin and yet does not warp in the firing! This mug has a weight-to-volume ratio of 2.08 (the weight of water it will hold compared to its own weight).

Related Pictures

A parametrically-drawn cookie-cutter for slab built mugs

A 3D printed cookie cutter showing parametric measurements, four of these are glued together

You may already know that I am very excited about the potential of 3D printing for creating aids to making pottery. I glue four of these together to create a cookie cutter for producing slab-built mugs. For different sizes of mugs I need cutters with different geometries. This is quarter-cutter and it has been drawn "parametrically" using Fusion 360. That means that certain aspects of its geometry (two lengths and one angle) can be adjusted by simply changing the parameters (in the Parameters dialog). The drawing then adjusts automatically. It is magic! Other aspects are fixed (e.g. the right-angle, the pucker-preventing hole cutouts, the height, and thickness). Parametric design is revolutionary, it fits my try-it-adjust-it-try-it-again way of working. And, I can label these printed quarters according to the size, in this case 45-25-108.

Large cookie-cutter 3D-printed in four pieces

These four sections were glued together to make a larger one. Now it is possible to quickly precision-cut the shape for making my pie-crust mugs. Later I re-printed these templates on a better 3D printer so the inner vertex holes cut out much better.

Mother Nature's Porcelain and Glaze!

Of all the pieces I make, ones like these mean the most to me. To make this cup I sieved a Plainsman 3D clay slurry to 325 mesh to produce a natural porcelain that vitrifies beyond the zero porosity point at cone 6, yielding incredibly strong ware. I make the outside and inside glazes from clays we mine in Montana and Alberta (using chemistry to maximize the clay percentage to more than 70%).

Get a kitchen blender for mixing ceramic slurries

Blender mixing is invaluable in slurry preparation in small scale ceramics and testing. It is quick and so effective that not only are particle surfaces wetted much better but clay particles can actually be reduced in size (literally ground finer). Slurry rheology is also stabilized. For example, thixotropy can often be achieved naturally, without any additives. Materials that are otherwise impossible to mix into a slurry (e.g. bentonite, Veegum, CMC gum) are no problem. Even slurry-processed porcelains benefit, not only being more plastic, but firing to a more homogeneous surface and to greater density. Just visually, it is easy to see how much improved this MNP slurry is (a local clay with porcelaneous properties). It was mixed using our propeller mixer and seemed OK (on the left). But the improvement after only 20 seconds in the blender (right) is amazing.

Links

Projects	Mother Nature's Porcelain - Plainsman 3B
Projects	Pie-Crust Mug-Making Method Tony Hansen's project to make light, strong and functional slab-built mugs using tools and templates made possible by 3D design and 3D printing.
Articles	How to Find and Test Your Own Native Clays Some of the key tests needed to really understand what a clay is and what it can be used for can be done with inexpensive equipment and simple procedures. These practical tests can give you a better picture than a data sheet full of numbers.

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