Don’t feel limited with regards to what your extruder can add to your studio. Custom dies can make a big difference, and they are easy to make. For those of you who don’t have an extruder, get ready to explore a whole new way to work with your pots! Most community studios have an extruder tucked into a corner someplace. I would like to encourage some ideas for ways to use that sometimes forgotten tool.

Using an Extruder

The basic idea is that clay is loaded into a tube, one end of which has a fitting that holds a disk with a designed hole or opening (see 2) that dictates the shape of the extruded clay. This is called the die. The other end has a ram or plunger that, with significant force, will push the clay through the die. There are two main types of die, solid shape (for a handle or a coil) and hollow shape (for a tube). There are numerous types of commercial extruders on the market, many of which you can make dies for. If you are considering buying an extruder (1), keep in mind that if you want to make solid shapes, you will want a smaller extruder. The larger extruders (used for hollow shapes) can make tubes that are from 4 inches wide/in diameter up to very large widths (the larger sizes are facilitated by an expansion chamber attached to the end of the extruder (see 1, right)).

1 A hybrid and a large extruder with an expansion box, both with stop platforms. 2 Various hollow and solid extruder dies, some custom made from UHMW plastic.

Fabricating Custom Dies

I have a fairly large collection of custom dies (2). Over the years, I have made hundreds of dies (not all shown), each one taking only 10 minutes to make with a scroll saw. I pick up scrap pieces of ultra high molecular weight (UHMW) polyethylene from a local plastic fabricator. This is an extremely tough, abrasion-resistant, low-cost plastic used for a wide range of wear applications. It is ideal to use for dies because it cuts smoothly and can bend without breaking. 

To make a tall vase, I need a custom hollow die with rounded corners and a custom solid die to make the trim for a cap on the vase. Start with a drawing for the cap (3). Add dotted lines to indicate how the piece will rest on the clay tube. Use rubber cement to glue the drawing to the blank piece of plastic. Drill out the two round areas that are marked with a dot—this type of plastic is very easily cut or drilled. Then, use a scroll saw (4), or clamp the plastic in a vise and use a coping saw with a sharp, small-toothed blade to cut out the rest of the shape. To get started, insert the blade into one of the two holes that you drilled. Trim any burrs with a utility knife.

3 Draw a die shape for the top cap extrusion, then attach it to the plastic blank. 4 Drill holes, then cut out the die with a scroll saw or a coping saw and a vise.

Because of the stress on the hollow-tube die, I increased the thickness of the plastic material to ¼ inch. Hollow dies have an outside section and an inside section, and simple U-bolts are used to hold the sections in place (5). When tightening the bolts, it is helpful to use shims to maintain even wall thickness (distance between the plastic sections). In use, clay is pushed through the extruder tube, it first separates as it passes by the bend of the U-bolt, then it reforms into a solid mass by the time it passes through the die. Tip: Softer clay is much easier to extrude. Stiff clay will drag on the die, often have flaws, and be twice as hard to press. Having said that, clay that is too soft will be more difficult to handle as the shapes exit the extruder. 

5 Attach the center section using U-bolts. Use shims as spacers.

Extruding the Vase Parts

First, secure the hollow die in the bottom of the extruder and load the barrel with soft clay. Attach the ram handle, and squeeze out any trapped air in the extruder. When the clay starts to emerge, adjust the stop platform for the length of extrusion you want. Trim the base of the extrusion and slightly flare it out so it is wider and gives the vase greater stability. Tip: Have several small bats available with holes in the center. The hole in the bat allows air to fill the inside of the extrusion so it doesn’t collapse during the extruding. Next is the fun part! With one hand, push up firmly on the bottom of the extrusion with the bat and pull down on the ram with your other hand. This action forces the clay to bell out in cool ways. When satisfied with the shape, continue to press the ram and extrude until the piece hits the stop platform (6). Carefully cut the top with a wire and set it aside.

6 Press the bat up against the clay tube while extruding to shape the bottom. 7 Score, slip, and attach a flat slab of clay to the bottom of the tube.

Next, attach a bottom to the vase. Very carefully score the bottom of the tube and check for any blowouts (holes or weak spots in the walls). Prepare an oversized slab, lay it on newspaper, then score and slip it (7). Carefully flip the tube over and onto the slab and give it a little wiggle to help the tube bond to the bottom. Trim off the excess clay close to the base. To ensure a good join, either pinch the pieces together or use a small wooden tool to lift clay up from the bottom over the seam. This join is made easier because both sections are still wet at this point. 

To extrude the trim for the cap on the vase, switch out the hollow die for the solid die made earlier in the process. I use a 2-inch solid extruder for this process. Extrude several lengths from that die (8). Set these aside while you move on to the stamping. 

Decorating the Vase

My favorite medium for stamps is wood; however, bisque-fired clay works very well. I’ve modified simple wood blocks with a wood burner to create symbols for seeds, roots, tree trunks, branches, and tree tops (9). 

8 Using the custom solid die, extrude several lengths of the top cap. 9 I use a wood burner to design seed, roots, trunk, and treetop stamps.

Because the vase must remain soft for this step, I slide a square wooden block into the tube to give it support while being stamped. I coat the wooden support with cooking spray so it slides easily inside the clay tube. You can now lift, turn, and stamp the soft tube without damage (10). Once the stamping is finished, trim the top of the vase level (see sidebar above) and wrap the top rim with plastic to keep it from drying out while you make the top cap.

Creating the Top Caps

Measure and cut 45° angles on the top cap extrusions. Assemble these sections like mini picture frames, score, slip, and press them together (11). Clean up with a brush and set them aside. Flip the picture frames upside down, score and slip both sections, then gently press them together and give a wiggle to join (12). Clean up with a wet brush, and use a wooden tool to smooth the inside join. You want to still keep all the pieces fairly wet, so move fast or keep wrapping with plastic. 

10 I use a wood burner to design seed, roots, trunk, and treetop stamps. 11 Cut the top cap extrusion at 45° angles, then assemble like tiny picture frames. 12 Flip the top cap and the vase upside down, then attach the two sections. 13 Press down on the rims to give a little more movement on the top.

I don’t feel that the top should be perfect and straight when the bottom was made a bit wonky, so press down on the top (13). It’s also fun and gives me a sense of artistic expression (14).

Glazing and Firing

Fully dry and then bisque fire the form. After bisque firing, I use a combination of two glazes. One is a reliable dark liner glaze; the other is a transparent glaze that plays well with the liner glaze. Over the years, I have tested many glaze combinations and I am looking for certain characteristics for the type of work, clay, temperature, and atmosphere. For example, my dark brown liner glaze holds its color no matter how thick or thin it is applied. For the second glaze, I modified a clear base glaze with a small amount of copper carbonate to give it a green tint. Then, I added extra frit to make it run down the pot. As it flows, it picks up some of the dark brown glaze and creates interesting movement. 

14 Clean up and adjust the shape of the top cap to mimic the bottom movement. 15 After the bisque, apply a glaze wash, lightly sponge, then apply a second glaze.

The first coat has to be thinned to work it into all of the tiny crevices. Then, I sponge off the main surface to highlight the texture (15). I use this same glaze for the inside of the vase, then dip the rim in the glaze bucket. The second coat is applied with a thick brush in a glob-on-heavy motion, that way I can control how thick the glaze is at the bottom of the pot. I always use thick wadding when I fire because you just can’t control everything.

Over 20 years ago when I first started working with clay, I was fascinated by the tool in the corner of the classroom. Give it try, it has great potential!

Tom Quest is a studio potter who lives in Omaha, Nebraska. To learn more, visit