Technical Specifications
Description
A rich terra cotta firing body for throwing, slab work and
sculpture.
Mesh : 14#
Recommended Firing
|
Bisque |
Glaze Soft colour |
Glaze Dark red brown colour |
|
1000° C |
1060° C to 1120° C |
1135° C to 1200° C |
|
Orton Cone 06 |
Orton Cone 04 to 02 |
Orton Cone 01 to 5 |
|
at 150° C per hour |
at 150° C per hour |
at 150° C per hour |
Coefficient of Expansion
Sample fired at 1060° C, Orton cone 4. Linear expansion is
0.335% at 500° C and coefficient is 72.6 x 10-7 from 200° C to 500° C.
|
Chemical Analysis |
Shrinkage (fired) |
|
SiO2 |
60.13% |
From wet to dry |
3.5% |
± 0.5% |
|
Al2O3 |
26.75% |
From dry to bisque |
0.3% |
± 0.2% |
|
TiO2 |
1.51% |
From bisque to glaze |
2.2% |
± 0.5% |
at 1060° C Orton cone 04 |
|
Fe2O3 |
5.34% |
From bisque to glaze |
8.0% |
± 0.5% |
at 1200° C Orton cone 5 |
|
CaO |
0.33% |
|
MgO |
0.95% |
Water absorption |
|
Na2O |
1.00% |
Biscuit |
1000° C |
Orton Cone 06 |
13% |
|
K2O |
2.55% |
Fired |
1170° C |
Orton Cone 3 |
less than 2% |
|
L.O.I. |
7.08% |
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 blunged, sieved and passed over rare earth
magnets, then stored in constantly agitated farm tanks. Final body blend is made
with millimetre accuracy with powdered raw materials being added and agitated
in. With this manufacturing method we can ensure reproducible recipe formulation
to within 0.1%. Final body in liquid form is sieved and passed over rare earth
magnets once again and then filter pressed. Filter pressed clays are then stock
piled in cake form and allowed to age. Extruding takes place through a de-airing
pugmill and clay is sealed airtight in polythene bags which can be stored
indefinitely.
