Bisque Molds and Serving Trays Tom Jaszczak

Appears in the May/Jun 2017 issue of Pottery Making Illustrated.

When I transitioned out of wood firing to soda-fired earthenware about five years ago, I was aware that new making techniques would open up, as my forms wouldn’t be subject to the extreme environment of wood firing. Handbuilding trays was one of those new techniques. Some of my favorite pots by fellow ceramic artists are of this genre—serving bowls made over a bisque mold by Matt Kelleher, the boat forms of Randy Johnston, and the large, origami-like trays of Mark Pharis.

Much of the larger work I make has come out of a necessity to see my surfaces on a larger scale. I’m truly content making dinnerware every day, but am always in pursuit of pushing ideas forward. To do this, I recognize the importance of making things outside of my comfort zone. Soon, these new works inform the comfortable ones, and the uncomfortable pots become my favorites to make and my work moves forward in an unexpected direction.

Building a Bisque Mold

I use bisque molds for several reasons. One is that I know how to use clay quite well and, another is that I don’t like using plaster, so I don’t. Creating forms using bisque molds is also a resourceful way to use up leftover clay scraps. A bisque mold is also a great solution if you need to add a foot to a form right away, because as a hump mold it provides an underlying armature to build onto.

There are several ways to make a bisque mold. I use a drape mold to make my bisque molds. I like this method for a few reasons. It’s a great way to take a simple two-dimensional drawing of a shape and turn it into a three-dimensional mold. I simply let gravity do the work. I’m fond of ovals, but you can use any two-dimensional shape to start with.

I learned a good trick for creating perfect ovals from my friend Gary Anderson. Put two screws or nails into a plywood board so that the space between them equals the length of the tray you want to make. Next, take a string and tie it together to make a loop that fits around the two screws. Then use a Sharpie marker and draw as you would with a compass along the curve of the tension of the string (1). The tighter the string, the more severe the oval; the looser the string, the softer the oval. If you want to make a different shape, just draw or trace your two-dimensional shape on a plywood board with a Sharpie.

Next, drill a ½-inch or larger hole somewhere inside of the Sharpie line. Take a jigsaw, insert it into the hole, and saw along the line (2). This may take several cuts if you’re using a more complex shape. The accuracy of the sawing is not essential, it just needs to be fairly close to the original. Save the interior cutout, as you’ll use it again later in the process.

Next, I roll out a slab of clay for the mold between ½–1 inch thick and compress the clay, leaving memory in the clay in several directions, rather than in only one direction, which can increase chances of warping later in the drying or firing process.

Lay the slab over the drape mold, then tap the drape mold on a table, allowing the clay to start slumping. Tap until the clay falls to the desired depth (3). Set the mold on some bricks or shims on each corner until the clay sets up. Tip: set up your shims before you start slumping the clay, so that they’re in place for you to rest the mold on as soon as it’s ready. If you want, once the mold is shimmed up, you can continue to develop the depth and curve of the mold using a rib or sponge.

One advantage of this method is that if I don’t like the initial mold shape, I just wedge it back up and start over with little time invested. You can also make several variations from the same drape mold just by making a different depth or pitch. And finally, you can also use the drape mold to make a pot directly, rather than making a bisque mold. Your shape can easily be made into a tray or bowl, or you can make two of the same and attach them together to create an enclosed vase form, a jar, a teapot, or a box. I use this method to make a bisque mold because it allows me to add a foot to the tray immediately, and I need this armature to do so.

Once the slumped slab firms up, pull it off the plywood and set on a work table. Next, cut off the excess clay and refine and shape the whole mold using a Surform (4). I then smooth out all the Surform marks using a sponge and an aluminum rib. You can leave the texture if you want, or add another texture. When the mold is dry, bisque fire it.

Forming the Tray

Once the mold is bisque fired, gather the plywood drape mold, the leftover interior plywood cutout, and the bisque mold. Set the plywood cutout back into the plywood board. Next, set the bisque mold on the interior piece of plywood. Because of shrinkage, the bisque mold should be just a little bit smaller than your original shape.

Now, roll out a slab of clay larger than the mold. The thickness is dependent on what you like in a pot, probably somewhere between ¼–1 inch. I prefer a lot of excess clay to play with while trimming, especially if this is the first time I’m making a pot. I find it’s easier to thin things out later than to add clay to a flimsy structure.

Take the clay slab and lay it over the mold (5). Once the clay is in place, use the side of your hand where the pot’s rim will be—where the mold meets the board—to compress to true up the edge to the mold the whole way around (6). Cut the excess clay from the slab, following the outside of where your hand compressed the clay along the rim (7). Cutting on the outside of this area leaves plenty of excess clay to figure out a rim solution. Then, roll the extra clay back into the tray with your hands and an aluminum rib, leaving a nice thick rim to blend into the profile of the pot (8).

Adding a Foot

To ensure the symmetry of a foot, first take a rib and use it to measure and mark out where you want the foot to go. Hold the edge of the rib against the form. Start from the base and move up to the middle, leaving a faint guideline to the pot’s symmetry. Do this on both long ends of the tray, and on each side. Then roll out a long, thick coil and score it. Once you’ve scored the foot and the tray, add the coil using the rib markings to guide placement. Now attach the coil to the tray, smearing the seam both inside and out to reinforce the attachment to the tray (9). Follow up with the rounded corner of a rib, running it around the seam to begin defining the foot’s bevel. I do this very crudely at this stage. Finally, lay a flat board over the entire foot, compressing gently so that it’s approximately level (10).

Now you have a complete, albeit unrefined tray upside-down on its mold. Lift the exterior plywood board, which will catch the rim of your tray and lift it right up off the mold, leaving behind both the plywood interior cutout and the bisque mold (11). Set the tray to the side until it reaches leather hard. Getting the tray off the mold immediately prevents it from cracking and shrinking onto the mold; also, because it’s already upside down, the rim is supported and air can reach all aspects of the pot simultaneously. Thus, you have a roughly completed tray with the least amount of handling, resulting in less deformities and future warping.

Trimming

Once the tray is leather hard, flip it upright and clean up the interior of the pot, defining where the interior meets the rim. Next, use a Surform to trim the rim to the desired thickness and shape (12).

Then, flip the tray back over and begin trimming the interior of the foot with a loop tool (13). This part can be difficult if the clay is not at the correct stage of leather hard, and may take some practice. The clay should be soft enough for you to keep a steady hand with the trimming tool and hard enough to hold its shape. Once you have the whole interior of the foot trimmed, follow up with a rib to define the rest of the foot’s interior. Then, define the exterior of the foot, again using a Surform to even out the thickness and shape the profile (14). Follow up with a rib again to refine the exterior of the foot. Now, take a board and gently move it around on the foot to catch any high points to trim down and make the foot level. Take a moist sponge to the foot to soften the edge. Finally, put a hole through the foot using a circular punch, so you can put a wire through it later for hanging (15).

Now that the foot is complete, move to the exterior wall of the tray and use a Surform to obtain the desired wall thickness and profile. After this is complete, I do a series of damp sponging and scraping with an aluminum rib to remove the Surform texture. Because of the coarse grog in my clay, this final scraping texture is what really brings out the brick-clay appearance in my work. Different clays will leave their own texture. Flip the tray over, right-side up, and clean up the rim with a sponge. It’s important to wait and finish the rim at the very end so it doesn’t lose its integrity.

Drying

Drying is always difficult for long, horizontal work like trays. I like to let the tray stand uncovered for a few hours after finishing, letting it re-gather its integrity. Then I place a layer of foam on the inside with weights on top to stop it from lifting or twisting while it dries (16). Depending on the climate, stages of wrapping-up and unwrapping in plastic might be required. Also, wrapping up the corners or the rim can help. I have had some success drying these trays upside down as well and this is certainly worth trying.

Finishing and Decorating

Once the tray is dry, bisque fire it. To finish my pieces, I dip the bisque-fired piece into a large trough of slip to get an even coat. The same technique can be used for glaze if that is your preferred finish. Once the slip is applied and dry, I clean up the foot and bisque fire the tray again to seal the slip onto the pot, so that I can add a final decorative layer before it goes into the soda kiln. This second bisque firing may not be necessary, depending on how you chose to decorate. Normally I put slip on leather-hard work, but I’ve found that the larger trays can’t handle the stress of being dunked in slip.

I have lost so many trays at different points of this process, but after initial frustrations, have enjoyed all the little moments of problem solving that goes with making larger ceramic work.

Tom Jaszczak is currently a resident artist at Penland School of Crafts in North Carolina. Jaszczak received a BA in Visual Art and a BS in Biology with a minor in Chemistry from Bemidji State University in Minnesota. See and learn more at www.tomjaszczak.com.

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