A clay extruder may be thought of as a large hopper with a press and multiple dies. It’s a simple device which is used to press clay into various shapes and patterns. Such extruders can be huge, car-sized, steam driven monstrosities or small presses you can hold in the palm of your hand. An extruder is often used to streamline the pottery process. Most are mounted to the wall of the room or studio they are used in for hands-free convenience. Some models sit on a table, but they work on the exact same principle. They are not necessary, but can be of great help in making things such as handles for pitchers. Extruders add a little bit of professionalism to your work as you don’t have to worry about handles or strips of clay being uneven like they are when rolled out by hand. Here is a guide on the correct use of an extruder.
Begin by figuring out how much clay you will need to make the strip or handle and double that amount. Work the clay with your hands thoroughly for 15 minutes, kneading it like dough and folding it over and over to work out any bubbles or air pockets that would give you trouble, making a strip when placed in the extruder. When you finish, you should have something roughly cylinder shaped and about an inch narrower in width than the hopper of the clay extruder.
Unscrew the bottom of the extruder where the clay comes out, and fit into place the die you intend to use to shape the clay. The most common dies that come with extruders are circles, squares and rectangles to make the basic shapes but you can also find more exotic shapes if you look in arts and crafts stores. Screw the bottom of the extruder tightly back into place.
Raise the piston on top of the extruder up out of the hopper. Typically the piston is connected to a lever which is in turn attached to a metal guide ring slotted through a bar rising above the hopper. This is to ensure the piston moves only up and down and creates the axis where the lever raises and lowers.
Fit the cylinder into the hopper and guide the piston back into the hopper to press against the cylinder. Lower the ring so the lever is level with the ground and then pull the lever down. You may need to lower the ring and pull the lever down several times before clay begins to come from the bottom of the extruder.
Pinch off the clay strip from the bottom of the extruder and carry it over to a work table once it’s the length you need.
Empty the extruder of the excess clay by pulling the lever all the way down until the piston reaches the bottom of the extruder. Then unscrew the bottom of the extruder and remove the die so it can be cleaned out later. You are done with the extruder and the device is in good condition to be used again whenever you wish.
Depending on the exact design, some clays that contain a lot of water such as white stoneware and porcelain cannot be used because they are rust proof. You should make sure the extruder you are using is capable of shaping the clay you are working with before you place it in the device. Cleaning them out afterward can be a very dirty job otherwise.