A few years ago my friend Michael Janes—a fellow clay artist and volunteer instructor in my Loveland, Colorado, clay program—walked into class and casually handed me an extruder die. He had made two of them (his own design), one for me and one as a gift to the classroom (1, 2). This particular homemade die can, of course, be used for anything but I use it to create the beautiful sides of baking dishes and planters (like the one shown below).
One of my favorite things about the design of this extruder die is the beautifully thick top edge as well as the inside edge at the bottom (see 1). This beveled-edge design makes it unnecessary to add a coil to the bottom inside of the baking dish as would otherwise be necessary. The die shape is designed so that the extra clay is incorporated into the extrusion, making the attachment to the slab bottom easy and efficient. It also makes the bottom inside edge smooth and more food friendly.
Essential Tool Kit
The most essential tools in my studio are my hands. The two most used pieces of equipment for my handbuilt pieces, though, are my Scott Creek extruder and my Brent slab roller.
Creating New Extruder Dies
When creating your own extruder dies, consider using the following materials: ½-inch plywood, ¼-inch plastic cutting board, or ⅛-inch aluminum sheet. An aluminum die is the most efficient—I have tried them all. Some extruder companies offer blank dies.
Draw your desired pattern on the blank die with a permanent marker. Be sure the die cutouts are consistent, and that the cross section is about ¼-inch thick (the walls of a proficient vessel are generally ¼ inch thick). Any inconsistency will, if too thin, create a weak spot, and if too thick, make the baking dish too heavy. To cut the die, drill a ¼-inch hole through one of your pattern lines. Then, continue to cut out the design using a 6-inch jewelers saw with a #5/0-sized saw blade. Be sure to leave ¾ inch of blank space around the die edge, as the barrel cap covers this section. Once the die is cut, there is no need to sand any of the edges as they need to be square for optimum extruding.
Extruding a Baking Dish
Cut a template out of tag board (or similar stiff material) to the size you want the baking-dish bottom to be (3). Take into consideration your clay body’s shrinkage. My template is 10×14 inches. Since my B-Mix clay body has a shrinkage rate of 20%, this means the finished pieces are 8½ × 12 × 2½ inches. The buff clay I use shrinks a bit less.
Roll out a ¼-inch thick slab, place the template on the slab, then cut it out, making a straight cut for the base of the baking dish. When attaching it to the sides, you’ll use the extra clay to strengthen the attachment. Next, extrude the pieces for the sides of the dish. For this large baking dish, extrude two pieces that will be joined together. Each of my extruded pieces are 26 inches long. Allow them to stiffen up for 15–20 minutes before assembling. It should be flexible, but easier to handle without stretching or distorting the extrusion.
Score and slip the base slab around the outer perimeter before attaching the extruded sides. Score and slip the bottom of the extruded sides. Place the extruded sides at least ¼–½ inch inside the outer edge of the base slab (4). Make a beveled cut on the side edges of the extruded walls where they will be joined together, join them (5), then add a small coil to the join to reinforce it (6).
A Perfect Incorporation
Baking dishes can be tricky; the joined edge between the bottom and the wall needs to be very secure to withstand repeated use in the oven. Use a red flexible rubber rib and sponge to smooth and secure the inside edge of the extruded walls to the bottom slab (7). Next, I use my custom, bevel-cut kitchen knife (see image 3, above extruder dies) to join the outside edge of the bottom slab to the outer walls by pushing clay from the bottom slab up onto the side walls (8). The final step is to use a wooden foot rib (see image 3) to make a nice rounded bead finish at the bottom of the dish.
The Little Bits
Any leftover pieces of extruded clay are perfect for making the handles, and bringing in design continuity. Add the handles and play with textures on the dish’s rim as well as the handles (9–11).
Once the baking dish is complete (12), cover in plastic and dry it slowly over the course of several days, turning it over and smoothing the bottom once it reaches leather hard.
More Design Options
This extruder design can be used to make any number of pieces, including planters, napkin holders, square-cornered baking dishes, butter dishes, and handles for other vessels and test tiles.
Thanks to my friend Michael, this extruder die has become invaluable in my clay making life. Everyone needs a baking dish!
Nancy Zoller has been a professional potter and teacher for 40 years. She lives and works in Loveland, Colorado. To see more, check out www.nancyzollerpottery.com.