There are a lot of moulds available in a variety of shapes and sizes through various suppliers. But sometimes you want a simple or special shape that is not available to buy. Fibre boards provide you with the material to make your own special moulds without great expense.
The ceramic fibre boards tend to come in a variety of thicknesses, mostly about 1 metre square. Boards in 10, 15 and 25 mm thicknesses are commonly available.
You should work in a well-ventilated area using a dust mask to avoid inhaling the dust and fibres. See Gregorie's Glass for information on safety.
You can cut a wide variety of shapes into fibre board with just a craft knife. You can smooth the shapes with just sandpaper. The shape can be smoothed with sandpapers in both natural and hardened states. If a lot of material is taken off hardened shapes, it is advisable to coat that area with hardener and cure it again to ensure maximum durability.
A question that will arise is whether to harden or not. This depends on the durability you require. A board that is not hardened does not require kiln wash when fired. However, as it is soft it is easy to break. A hardened fibre board mould always requires kiln wash or other separator. It does become durable and almost rings when tapped once it is hardened and cured. If the shape needs to be preserved for further use, hardening is advisable.
It is also possible to stack the boards to make deeper forms. The boards should be stacked and pined together with copper of high temperature wire such as kanthal to keep them from moving both while shaping and in use.
Fibre boards are relatively inexpensive, in comparison with commercial moulds. They are not as durable as some, but provide a means of obtaining special shapes unique to your work.