Ceramic - Pottery Dictionary

by Susan Mussi

EXTRUDER (3) Electric for compressing and recuperating clay.

ca: EXTRUSORA (3) Màquines elèctriques per a comprimir i recuperar l'argila.

es: EXTRUSORA (3) Máquinas eléctricas para comprimir y recuperar la arcilla.

Extruder – electric also known as a Plug Mill. It is a machine for compressing and recuperating clay so that it can be used again and it improves its strength and workability. There are many types of extruders for big industrial businesses and for small studios. They are made for mixing clay into a usable, pliable state and expelling it in large coils.

An extruder should only be used for one type of clay as cleaning them well is nearly impossible and clays should not be mixed. When clay is in the state to use but has too much water, never separate it from the water as it has many substances that it needs. Let it dry until it can be passed through the extruder.

The large industrial ones are used in the final stages of making clay that has been taken out of the earth, dried, sieved many times using meshes that are gradually getting finer and finer, then mixed with water, passed again through a sieve and left to dry to a pliable state, then passed through the extruder.

These photos show one of the smallest that is simple and good, with an arm that forces the clay down which is pulled across from one side to the other. Many are made with arms that move length wise.

The neck is filled up with clay and with the machine working the handle is pulled down, this forces the clay down and through the mixer, then the lid is lifted and more clay is added. This is repeated and the pressure pushes the clay down the tube forming a large solid coil until it comes out on to the long plank at the front and can be sliced into the lengths needed with a wire cutter.

Read more about: Extruder (1) Electric / Extruda (2) Manual / Extruder (4) How to keep it