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.
P700 is a smooth and slick fine grained body. And it is very plastic (if not too soft). It has enough added bentonite to give it better plasticity than than H570! Of course, this means you must take precautions when drying (dry ware evenly).
P700 fired bars. Cone 10R top. Cone 6-11 (bottom upward).
P700 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).
As with any zero-porosity porcelain, 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 to the shelf during firing.
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. Base matte and glossy glaze recipes can be found on our website.
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.
P700 with pure Alberta Slip as a glaze. Fired at cone 10R.
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.
We do not supply a thermal expansion value. The reason is that such numbers often mislead users. First, a body has different thermal expansion characteristics when fired at different temperatures, schedules and atmospheres. Dilatometers are only useful when manufacturers can measure bodies and glazes over time and in the same firing conditions. If a chart is supplied here, please view only as a way to compare one body with another.
Another significant issue is that many customers compare measured thermal expansion numbers with calculated values of glazes in efforts to fits those glazes to a body. This does not work. Calculated values are relative only and have limitations that must be understood. The best way to fit glazes to your clay bodies is by testing, evaluation, adjustment and retesting. For example, if a glaze crazes, adjust its recipe to bring the expansion down (using your account at insight-live), fire a glazed piece and thermal stress it (300F into ice-water). If it still crazes, repeat the process.
If we recommend a base clear or glossy glaze, try calculating the expansion of that as a rough guide to know whether your glazes will fit.
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
Cone 8: 7.5-8.5% Cone 10: 8.0-9.0 Cone 10R: 8.5-9.5
Cone 8: 0.2-0.8% Cone 10: 0.0 Cone 10R: 0.0
CaO 0.2 K2O 3.2 MgO 0.3 Na2O 0.6 TiO2 0.0 Al2O3 23.9 SiO2 64.6 Fe2O3 0.5 LOI 6.6%
P700 cone 10R Mug by Tony Hansen. Alberta Slip (pure) outside, G1947U transparent inside.
H570 vs. P700. Clear glazed. Cone 10R.
Safety Data SheetClick here for web view.
|Plainsman Clays Ltd.|
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508