Master mould and working mould

Mould making is a fundamental process of the slip-casting technique. This valuable skill ensures that I can design my own prototypes and produce moulds and master moulds of my own design in my own studio, instead of relying on commercially available moulds.

Slip casting moulds must be made from a specific grade of Plaster of Paris, which needs to be mixed to a specific density to ensure correct casting rates and mould strength.

To begin with, a three-dimensional Plaster of Paris prototype of the new design must be made. This prototype needs to be larger than the envisaged fired or finished size of the final product, to take into consideration the shrinkage of the clay during drying and firing.

A mould is made from this plaster prototype, and a master mould is then cast into this mould. A master mould is the mould from which working moulds are cast. Master moulds must be stored in pristine condition, so that new working moulds may be cast from then as old moulds wear out.

Once a working mould has been made, it must be dried out completely before use. Be careful of kiln-drying new moulds - if the temperature is too high they can become brittle and may even explode in your kiln! (ask me, I know!!). keep the temperature below 40 degrees Celsius for drying moulds.

When working with Plaster of Paris always ensure that you do not contaminate your clay or work surfaces with Plaster. Clay and Plaster do not mix well! If you happen to get bits of plaster mixed up in your clay, horrible things can happen in the kiln!

Plaster of Paris contamination can cause blow outs and explosions during the firing process.
New moulds may have to be 'worn in'. this means that the first few casts me be lost, as the clay does not release properly from the mould.

SILICONE RUBBER MASTER MOULDS FOR CERAMICS:

Master moulds for ceramic moulds can also be made from silicone rubber. The material is quite expensive, but lasts longer than a plaster master mould and eliminates the use of releasing agents. The flexibility of the material also ensures that your master/working mould will not be damaged in the casting and releasing process.

Tools

SILICONE RUBBER MOULDS:
There are a wide variety of silicone rubbers and resins available, which are ideal for mould making for other industries or projects.

Silicone rubbers produce flexible moulds which make it easy to release the form from the mould.  They are also very durable and long lasting. Silicone rubber  is the preferred material for flexible molds because of its strength, elasticity, durability, and ability to hold fine detail.

We will be happy to discuss your mould needs with you, and give you details and suggestions for your mold project.  Since each mold is different, we will need details on your project before quoting prices.  Please email us with your inquiry.

Client's commission fish mould made from silicone rubber	Client's commission fish moulds and master mould
Pig mould and prototype	Pig mould and prototype

Tools