An Extruder and die for making coils

There are many extruders on the market, most of which provide for the possibility of creating your own dies. The coil thickness that is ideal for coil-and-throw is variable depending upon the desired wall thickness of the pot and the stiffness of the clay. The Coil-and-Throwmaster comes with a set gap of 6mm between the rollers – a gap that will produce a wall thickness suitable for most large pots. Experience demonstrates that a circular coil of 25mm diameter (1 inch) suits best. At those settings, each coil will add approximately 40 – 60 mm to the height of the pot.

A heat source to stiffen the wall

In order that the accumulated weight of each successive coil is supported, an essential part of coil-and-throw is that the wall of the pot is stiffened as it is built. Application of heat to the clay accelerates drying by driving off the moisture which increases the standing strength of the clay. For this method of coil-and-throw, the applied heat should be concentrated on the clay wall in the region of the new join and away from the rim. This will leave the rim soft and ready to join the next coil, and the wall supportive of the weight.

The preferred choice is a propane blowtorch because it can deliver sufficient heat quickly and focus the heat where it is needed.

A common choice is an electric heat gun of the type designed to strip paint. These are adequate for the purpose but are slower to achieve the desired effect and the heat is not as focused.