F100G

Description

White grogged sculpture body made from talc and ball clay (the same recipe as L213 but 20% of the talc has been substituted for 35 mesh grog and silica sand). This body is commonly used to make large pieces.

Process Properties

Talc/Ball clay bodies are very plastic and at the same time dry well. The additional fine silica sand and grog give this body even better drying capabilities. Despite this, F100G feels quite smooth. We recommend F100G when sculptors need high certainty that ware can be dried without cracks while still having a relatively smooth fired surface. One caution: Its dry strength is fairly low, handle dry ware with care.

Firing

Very white burning. The high plasticity of F100G slows drying and makes it susceptible to failure in the early water-smoking phase of firing. Make sure pieces are thoroughly dry before firing. Preheat your kiln overnight, or even for a full day, if pieces are large.

F100G can be fired to cone 4 fairly safely. At cone 6 it still appears to be stable visually, however the fired shrinkage and porosity have already reversed (indicating firing volatility).

Glazing

Since F100G does not contain quite as much talc as is customary in low fire talc bodies, some commercial glazes could craze over time. Since it is grogged, the glaze layer needs to be thick enough to cover any exposed particles (to assure a smooth glassy layer). For dipping glazes, this is not a problem, but for paint-on ones be sure to put on three layers.

Thermal Expansion

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 (using an IWCT test, 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.

Physical Properties

 Drying Shrinkage: 4.5-5.5%
 Dry Strength: n/a
 Drying Factor: B110
 Water Content: 19.5-20.5% Mar 99
 Dry Density: 1.95

Sieve Analysis (Tyler mesh):

     +48     (300 microns): 0.0-0.6%
   48-65 (300-210 microns): 0.4-0.8
  65-100 (210-149 microns): 2.5-3.5
 100-150 (149-106 microns): 2.0-3.0
 150-200  (106-75 microns): 5.5-7.5
 200-325   (75-45 microns): 7.0-10.0

Fired Shrinkage:

   Cone 04: 1.0-2.0%
  Cone 02: 1.5-2.5
  Cone 2: 2.0-3.0
  Cone 4: 2.5-3.5
  Cone 6: 2.0-3.0
 

Fired Absorption:

   Cone 04: 11-14%
  Cone 02: 10.5-13
  Cone 2: 10-12
  Cone 4: 10-11.5
  Cone 6: 9.5-11

Gallery