P700

High temperature Grolleg porcelain. P700 is our most vitreous cone 10 white body, it is the closest thing we have to a true translucent porcelain body. P600 is a mix of 50% Grolleg kaolin with feldspar and silica. We also add micro-fine bentonite to improve its plasticity.

Process Properties

P700 is a smooth and slick fine grained body. It is not a pure Grolleg porcelain (containing only Grolleg, feldspar and silica), it has added micro-fine bentonite to improve plasticity. In fact, there is enough added bentonite to give it excellent plasticity (although P600 is a little more plastic). You must take precautions when drying and handling dried ware, P700 simply is not as easy to use as a typical stoneware body (more drying cracks, dried ware will be much more fragile).

Firing

Cone 10ox

Cone 10r

P700 is true translucent porcelain, it vitrifes to a very pleasant silky surface and is translucent on thin pieces. Compared to our other porcelains, P700 burns to a distinctly blue-white tone at cone 10 reduction firing (compared to the off-whites of the others).

P600 and P700 are our most dense firing bodies, they burn to zero absorption at cone 10 and 10R. As with any such porcelains, fired warping is always an issue, you can manage this by avoiding shapes that lack structural strength (i.e. straight sided cylinders, goblets with flared bases, overhung bowls). Be careful to use kiln shelves that are flat. Kiln wash is needed to prevent pieces from sticking.

Glazing

P700 employs only kaolin (rather than a kaolin:ball clay mix of most porcelains). It thus has a lower silica content and so crazing may occur if your glaze has a high thermal expansion.

In addition, this body fires to a high strength, a strength that can be severely compromised if a glaze is under excessive tension. We recommend stress-testing a piece of ware using a boiling water:ice water test. Ware should be able to survive several two-minute cycles before trouble appears. If you need assistance to adjust the thermal expansion of your glazes, please call Plainsman.

If you wish to use slip on your ware, make it from a base of P700 for the best possible drying shrinkage/fired shrinkage match.

Glaze Recipes

You can develop a compatible glossy or matte base for this body from our suggested starting point base recipes available on our Internet web site at http://digitalfire.com/education/glaze/cone10.htm. Information is given on how to fit the glaze to your body and how to customize it it for colors, opacity, speck, variegation, etc. For slip decoration, be careful to match drying and fired shrinkage of the slip with the body since low temperatures generate little glass to adhere the slip.

Physical Properties

 Drying Shrinkage: 5.0-5.5%
 Water Content: 23.5-24.5%
 Drying Factor: D542

Sieve Analysis (Tyler mesh):

     +100: 0.0-0.1%
 100-150: 0.1-0.3
 150-200: 0.2-0.8
 200-325: 3.0-5.0

Fired Shrinkage:

   Cone 8: 7.5-8.5%
  Cone 10: 8.0-9.0
 Cone 10R: 8.5-9.5

Fired Absorption:

   Cone 8: 0.2-0.8%
  Cone 10: 0.0
 Cone 10R: 0.0

Chemical Analysis

 CaO       0.2
 K2O       3.3
 MgO       0.3
 Na2O      0.7
 TiO2      0.0
 Al2O3    23.2
 SiO2     65.5
 Fe2O3     0.5
 LOI       6.3%

Plainsman Clays Ltd.
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX: 403-527-7508
Email: plainsman@telus.net

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