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 relies almost entirely on plastic kaolin for workability and dry strength (although there is a small amount of added bentonite). P700 thus compromises plasticity and dry strength for fired whiteness, (if you need more plasticity use P600). The precautions needed to use true porcelains like this are well known and documented in text books, they simply do not drying and work as well as stoneware.

Firing

P700 is true translucent porcelain, it vitrifes to a very pleasant silky surface and is translucent on thin pieces. P700 is our most dense firing material and fires to zero absorption at cone 10 and 10R. As with any such porcelain, fired warping is always an issue, you can manage this by avoiding shapes that lack structural strength (i.e. a straight sided cylinder, goblets with flared bases, overhung bowls). Kiln shelves obviously need to be flat also and kiln wash is needed to prevent pieces from sticking.

P700 and P600 are our whitest firing bodies. P600 is darker but more plastic.

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.
Box 1266, 702 Wood Street, Medicine Hat, Alberta T1A 7M9
Phone: 403-527-8535 FAX: 403-527-7508

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