Casting Process

A process of preparing a green shaped article, the process comprising the following steps:

• a) providing a substrate at an initial predetermined spacing from one or more liquid dispensing outlets;
• b) writing a predetermined amount of a liquid formulation from at least one of said outlets onto the substrate, said formulation comprising:
• 8 to 99.99% by weight of a liquid sol comprising a liquid carrier and from 5 to 50% by weight, based on the weight of the carrier, of colloidally dispersed nanoparticles having a mean particle size in the range 0.25 to 100 nm;
• 92 to 0% by weight of a mineral powder having a mean particle size greater than 0.1 micron, and
• 0.01 to 10% by weight of at least one ingredient selected from surfactant, freezing point depressant and rheology modifier;
• c) providing cooling to said liquid formulation on the substrate so as to permit at least partial freezing of the carrier on the cooled substrate;
• d) increasing the spacing between the one or more dispensing outlets and substrate to a further predetermined spacing;
• e) writing a further predetermined amount of the liquid formulation from at least one of said outlets either on to the substrate or on to deposit formed in steps b) and c);
• f) providing cooling to said liquid formulation on the substrate or on the deposit so as allow at least partial freezing of the liquid carrier on at least one of the substrate and the deposit;
• and
• g) optionally repeating steps (d), (e) and (f) one or more times.