Casting Slips
Casting
Powders Casting
Slips Casting
Slip Recipes Casting
slip records
Walker Ceramics has an extensive range of prepared casting slips.
Preparation involves only the addition of measured amounts of
water and deflocculents.
We strongly recommend that casting slips should be tested for suitability
prior to any bulk use.
All slips are available in 5
litres, 10 litres, and bulk quantities for your own
production.
**Slips may be coloured with the addition of stains suitable for
clay bodies.
Imperial Porcelain 4317 (AB1)
An amazing, white, translucent world class Australian made porcelain. Superb whiteness and strength.
Fully ball milled for the smoothest of results. Fires from 1220-1300°C. Suits
all standard stoneware glazes.
Superior White Porcelain (AB10)
A fantastic new Australian made porcelain.
All Australian materials. Superb whiteness and strength. Proven throughout
Australia as a throwing, pressing, casting and hand building body.
Renowned for it's
consistency and
workability.
No.10 Stoneware (AB100)
Fires between 1240-1300°C. Excellent
glaze colour development on this white body. It is suitable for both Middle Fire
and Stoneware glazes.
White Earthenware / Middle Fire (AB300)
The body should be biscuit fired at
1000°C (minimum) and then appropriately glazed and fired from 1060 - 1250°C. This
will cover the full range of our standard Earthenware and Middle Fire glazes.
Terra Cotta - add Terra Cotta Concentrate to your choice of white
slips.
Auscraft Ultra White (AB450)
This body has excellent pouring and
working properties and high green strength. Fires to Ultra white .
Biscuit
at 1060 to 1100°C Orton Cone 04 - 03 .
Glost to 1000 - 1060°C Orton Cone 06
- 04.
Suits all Hobby Ceramic Glazes. Especially WHG400 Clear Gloss.
White Midfire (AB175)
This body has been
designed with extra whiteness for the people who want Porcelain / Stoneware
strength with the brightness of Earthenware colours at MIDFIRE temperatures.
Biscuit at 1000 to 1060°C Orton Cone 06 - 04 .
Glost to 1200 - 1220°C Orton Cone 5-6.
Suits our range of Mid Fire glazes.
Bone China
(AB505)
Fine quality AUSTRALIAN made Bone China.
Beautiful whiteness and translucency second to none!! Biscuit 1000 C Glost to
1250 C. Use EN250 Clear Glaze
TECHNICAL DATA
* AVAILABLE IN PLASTIC ◄
AVAILABLE IN POWDER
Deflocculants
The amounts of Sodium Silicate or Dispex N40 added to a casting
slip are very critical and too much or too little may each result in the slip
being too thick. If this happens, take a 1 litre sample of the slip and add one
or two drops of Dispex N40. If the slip becomes thinner after stirring then this
shows that more is required to achieve good fluidity. If the slip becomes
thicker then this shows that too much has been added already. Therefore more
clay and water needs to be mixed into the slip in the same proportion as given
in the casting recipe – no more Sodium Silicate or Dispex N40. The recipe can
depend on the quality of the water supply, which may vary from one location to
another and also may be affected by minor variations in the body’s raw
materials.
Maturing the slip
On standing overnight the slip may thicken up slightly. This
will easily reblend when mixing is resumed, even by hand. We recommend that at
the end of the day's production a thin film of water, approximately 2mm thick, is placed on top of the slip. This will reduce water evaporating from the mix, especially in warmer
weather. Simply mix again the following day.
Litre Weight Checks
The most important part of successfully mixing casting slips
is getting the correct litre weight. For accurate and easy litre weight
measurement contact Walker Ceramics for a
Walker Ceramics Litre Weight
Bottle and chart
Recycling Scrap
Great care is needed to avoid contamination, particularly from
plaster moulds. Scrap should be kept in sealed containers in a plastic
condition. Dry scrap will promote air inclusion in the slip. Recycle by adding a
maximum of 20% of scrap. More than 20% can effect the quality of the slip. We
recommend adding Barium Carbonate (BaCO3) to the
slip to remove
sulphates, which may cause peeling faults. The amount of Barium Carbonate to add
should be 0.1% (25gm per 25 kg bag) of the total dry weight of clay and scrap.
Faults and Remedies
Everybody who casts suffers from time to time from some form
of casting trouble. Walker Ceramics' experience of the industry, combined with the
extensive work done on casting slips in our laboratory has enabled us to connect
the various faults with measurable properties of the slip.
Of course, other factors besides slip properties can cause casting faults, but usually they can be easily noticed; for example, wet moulds
causing slow casting, careless filling causing 'pinholes' or 'casting-spot',
etc.,
The table shown gives a brief description of each of the
common troubles and the suggested remedies. This only gives the direction in
which to move and it is up to the individual to determine how far they need to
go.
Say you were suffering from flabbiness and you increased the
Dispex addition to correct this then found that you began to get brittle ware
with casting spot, then you would know you had gone too far. The following table
will help you in recognizing and fixing common problems. Thixotropy is the
property of slips becoming thicker when they are at rest i.e. "thixotropy
too high" means that the slip thickens up very quickly!
