P600

High temperature, smooth, medium plastic, vitreous, white firing, refined body for reduction and oxidation porcelain functional ware. P600 is intended to provide the most porcelainous nature possible in a plastic vitreous cone 10 white body. It is made from a 50% plastic kaolin blend along with equal proportions of nepheline syenite and flint. Due to variations in the kaolin we add micro-fine bentonite and adjust its amount from run to run to maintain plasticity.

P600's recipe is such that if we experience variations in the raw materials, the body is more dramatically affected than others. It requires close supervision and adjustment on our part to maintain its fired properties. Occasional variations in kaolin have forced us to add some ball clay to the recipe at times (resulting in slightly darker firing).

Process Properties

P600 is a smooth and slick fine grained body. It does not contain ball clay, only plastic kaolins and bentonite impart its plasticity and drying strength. This gives it a different plastic character than white stonewares (which always contain ball clay). Still P600 is plastic and throws remarkably well, especially when not too soft.

However since it is lacking the particle size distribution of more traditional white stonewares it demands more than the usual attention during drying, especially on difficult shapes (like large flat plates). Time is required to remove all the water since the bentonite acts as a barrier to its passage. If you need to join sections, be sure to follow good practice (i.e. use slip containing a clean aggregate grog (like molochite), use as much pressure and lateral movement as possible when joining, dry pieces evenly, avoid making ware with an uneven cross section.

Firing

Cone 10ox

Cone 10r

Although P600 is not a true translucent porcelain, it does vitrify to a very pleasant silky surface and does display a measure of translucency on thin pieces. P600 normally reaches zero absorption at cone 10 and 10R. If ware made from it has a shape that is not structurally strong (i.e. a straight sided cylinder, goblets with flared bases, overhung bowls) it is likely to warp, especially if set on kiln shelves that are not flat.

P600 has a more pleasant vitreous surface than H570 and fires whiter but it is more prone to warping during firing. P700, on the other hand, is whiter than P600 and even more vitreous.

Thermal Expansion

The chart shown was produced from a specimen fired once to cone 10 reduction in the Plainsman lab and tested in an Orton dilatometer. If you fire to a different temperature, employ different heatup or cooldown rates, or glaze-fire more than once the thermal expansion in your ware may be different than this chart indicates.

Thermal
Expansion Chart
Average: 5.5

Glazing

P600 is a variation on the widely used '25% Porcelain' recipe. However it uses only kaolin rather than a kaolin:ball clay mix. 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 that you stress-test 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 P600 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: 5.0-6.0%
 Dry Strength: n/a
 Water Content: 22.0-23.0%
 Drying Factor: C110-C120
 Dry Density: n/a

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: 0.2-0.5%
  Cone 10: 0.0
 Cone 10R: 0.0

Chemical Analysis

 CaO       0.3
 K2O       0.0
 KNaO      0.1
 MgO       0.5
 Na2O      0.0
 TiO2      0.9
 Al2O3    26.6
 P2O5      0.0
 SiO2     63.6
 Fe2O3     0.4
 FeO       0.0
 LOI       7.6%

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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