
chamotte gravel
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All prices incl. VAT, plus shipping costs.
For deliveries to countries other than Germany
the final prices may change in the checkout.
MORE INFO
For the production of plaster-bonded investment materials for bronze casting using the lost wax process.
Refractory chamotte gravel made from fired and ground light-coloured clay with a grain size of approx. 0 - 3.55 mm.
Processing:
To produce an investment for wax models for the lost wax process in bronze casting, mix 1 volume of chamotte gravel with 1 volume of plaster (e.g. alabaster molding plaster) and 1 volume of water to produce a homogeneous, flowable, not too dry and not too watery mass that can be processed immediately - the processing time is only a few minutes until the investment starts to harden. Make sure that you do not pour the plaster-fireclay mass directly onto the wax model during embedding to avoid damaging it.
If the mass is too watery, the fireclay parts may sink to the bottom, which will have an unfavourable effect on the quality of the casting mould. To make the mixture more stable, add more plaster and fireclay if necessary (always in a 1:1 volume ratio).
Mix as much investment as possible to completely fill your mould. If you mix and fill the investment in two or more portions, the masses may be slightly different, resulting in layering, which can also have an unfavourable effect on the casting mould.
bildhau tip for preparing an outer mould:
A wooden box is suitable as an outer mould, but also a piece of plastic drain pipe from the DIY store, for example. The drain pipe is first cut open at one point and then glued together again from the outside, e.g. with adhesive tape, to make it easier to remove the fireclay plaster mould after hardening. Then fix the plastic pipe to a wooden board. Insert wire mesh (chicken wire, chicken wire) about 1 cm from the edge to provide the plaster fireclay mould with reinforcement. Place the wax model together with the sprue and venting channels in the centre of the wooden plate. The wax model can be degreased beforehand with spirit or lightly coated with talcum powder so that the investment adheres better and there are as few air bubbles as possible on the surface. Then carefully fill in the investment.
Further steps until bronze casting:
Once the plaster-fireclay compound has hardened completely, the wax must be melted out of the mould (lost pattern method). To do this, place the mould with the opening facing downwards and a drip tray, e.g. in an electric kiln, to melt out most of the wax at up to 100° C. Then heat the kiln to > 800°C to allow the water trapped in the mould to escape and to burn out the remaining wax. This process can take several hours or even days.
To be sure that the fireclay plaster mould is really dry when casting the bronze (otherwise the bronze may splash out again when pouring), you should either pour into the still hot mould or reheat the cooled mould to 100° - 200° C to evaporate any remaining moisture before pouring in the bronze.