Technical Specifications
Description
Raku is a hardy, coarse clay ideally suited for the hand
building of large work, slab building and sculpting. Raku has the strongest thermal stability of all our bodies.
Mesh : Open
Recommended Firing
|
Bisque |
Glaze |
|
1000° C |
1000° C to 1300° C |
|
Orton Cone 06 at 150° C per hour |
Orton Cone 06 to 10 at 150° C per hour |
|
Chemical Analysis |
Shrinkage (fired) |
|
SiO2 |
64.98% |
From wet to dry |
4.5% |
± 0.5% |
|
Al2O3 |
29.32% |
From dry to bisque |
0.5% |
± 0.2% |
|
TiO2 |
0.82% |
From dry to glaze |
3.0% |
± 0.5% @ 1300° C |
|
Fe2O3 |
1.96% |
|
CaO |
0.25% |
Water absorption |
|
MgO |
0.49% |
Biscuit |
1000° C |
Orton Cone 06 |
23.0% |
|
Na2O |
0.56% |
Fired |
1300° C |
Orton Cone 10 |
12.0% |
|
K2O |
1.61% |
|
L.O.I. |
8.75% |
Glazes
Decorative (non-functional) glazes are available in the
Walkers Raku, Earthenware and Stoneware glaze ranges.
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.
