Technical Specifications
Description
Walker Ceramics Terra Cotta body is ideal for throwing, slab
work and sculpture. School Terra Cotta is designed to be easy to use and very
forgiving for school use.
Recommended Firing
|
Bisque |
Glaze |
|
1000° C |
1080° C to 1135° C |
|
Orton Cone 06
at 150° C per hour |
Orton Cone 03½ to 01
at 150° C per hour |
|
Chemical Analysis |
Shrinkage (fired) |
|
SiO2 |
53.77% |
From wet to dry |
4.6% |
± 0.5% |
|
Al2O3 |
25.38% |
From dry to bisque |
1.0% |
± 0.2% |
|
TiO2 |
1.41% |
From bisque to glaze |
2.4% |
± 0.5% |
at 1060° C Orton cone 04 |
|
Fe2O3 |
6.00% |
From bisque to glaze |
7.0% |
± 0.5% |
at 1200° C Orton cone 5 |
|
CaO |
0.28% |
|
MgO |
0.94% |
Water absorption |
|
Na2O |
0.94% |
Biscuit |
1000° C |
Orton Cone 06 |
11% |
|
K2O |
2.44% |
Fired |
1200° C |
Orton Cone 5 |
less than 2% |
|
L.O.I. |
7.24% |
Fired |
1225° C |
Orton Cone 6 |
0% |
Glazes
See Walkers Earthenware glaze range for functional and
decorative glazes.
If making your own glazes contact us for technical assistance
if required.
Presentation
Fully de-aired 10 kilogram block wrapped in recyclable
polythene bags.
Moisture content of standard clay is 22% to 24%, PR 3 to 4.
Other moisture contents are available on special request using
our Penetrometer Readings (PR) outlined below.
|
PR |
Consistency |
|
2 to 3 |
Soft |
|
3 to 4 |
Ideal throwing |
|
5 to 6 |
Firm throwing, slab work |
|
7 to 10 |
Slab, pressing or extruding |
Preparation
Crude clays are hammer milled dry. Blending takes place in a
ribbon blender where grog and powdered materials are added. The dry mix is then
extruded through a de-airing extruder. Moisture is added to the dry body
accurately in the extruder. The result is incredible plasticity and strength.
The clay is sealed airtight in polythene bags which can be stored indefinitely.
