White egg basket, 20 in. (51 cm) in length, porcelain, electric fired to cone 6, 2015.
Slip casting as a part of my studio practice is new for me. My education in clay was almost exclusively on the potter’s wheel, surrounded by a group of strong utilitarian makers who taught me to highly value craftsmanship and skill. Early on, my preconceived notions about slip casting led me to see it as a way of making pots that resulted in simple production ware that lacked any evidence of the hand.
As an apprentice I learned the importance of diversity within my making processes. With the goal of ultimately becoming a diverse and efficient studio potter, I see having the skill to both throw and use molds as ways to keep my studio life engaging and constantly evolving.
In homage to a favorite food of mine, often found at family reunions and church potlucks, I have worked to visually and conceptually elevate the deviled egg with my egg tray. For me, the egg tray I have created represents everything that industry is not, and it replaces the plastic egg keeper I grew up with. I use the egg tray mold as a tool, as a means to an end, and to challenge myself to make each tray a little different.
1 Turquoise and chartreuse egg tray, fired to cone 10, 2014. 2 Turquoise and yellow egg tray, fired to cone 6, 2015.
Creating a Template
I am now working with the second generation of the egg tray. During the past year of using the original mold and finished tray, I found that there were design adjustments I wanted to make. Andrew Martin’s book, The Essential Guide to Mold Making and Slip Casting provided a starting point for this design.
I begin the design process with a template based around the pattern I chose for the arrangement of the eggs (1). For this tray, the scalloped oval echoes the shape of the egg. Once a final design is established the template is laminated with packing tape, to make it reusable, and cut out. A scaled-down version of the template is created for the base, then both paper templates are traced onto a sheet of Masonite and cut out using a jigsaw. Then support boards are placed between the top and bottom profile boards (2 and 3). Clay is packed into the negative space to create the middle section of the tray (4). Once the clay is packed solid, this section of the tray is shaped with a wire tool and large ribs. The piece is then flipped over and a thick slab is placed on the top board. This slab is shaped into a slight dome (5), which helps prevent slumping and creates depth for carving the egg divots.
After the top profile is refined, the original template is placed back on the form and the egg placement, determined in step 1, is traced onto the wet clay using a ball-tip stylus (6). The divots for the eggs are carved using loop tools and refined with plastic ribs (7).
1 Make a template for the top of the egg tray. A matching smaller template for the bottom of the egg tray is designed to mirror the top profile. 2 Trace the laminated paper templates onto a piece of Masonite and cut them out using a jig saw or skill saw. 3 Align the top and bottom profiles with spacer boards in-between and secure with screws or a nail gun.
4 Pack clay into the open space between the top and bottom boards.5 Remove excess clay as the tray form is shaped. Place a slab on the top of the tray and mold into a slightly tapered dome. 6 Place the top laminated template on the form. Trace the pattern of ovals onto the top of the form.
7 Carve divots for the eggs using loop tools. 8 Cast the top of the mold first. Create a baffle with thick slabs to mask off the bottom section of the tray from the top. 9 Secure aluminum roof flashing around the form, then carve round keys for fitting the mold together later as it is cast.
Building a Mold
The top of the mold is cast first. To do this, a baffle is created with thick slabs to mask off the bottom section of the tray from the top (8). Key holes are carved into the baffles. The form is surrounded with aluminum flashing, plaster is poured, and allowed to cure (9). The aluminum flashing is removed, the entire piece is flipped over, and three coats of oil soap are applied to the first plaster section as a release agent (10). The flashing is secured around the mold again, then the middle section is poured (11). It is poured level with the bottom of the foot, allowed to cure, and the flashing is again removed (12). I learned with the first version of this mold that anywhere I can reduce weight and excess plaster is time well spent as it makes the mold infinitely more manageable. With this mold, I spent time shaving as much excess plaster off as possible (13). I also poured a much smaller foot section (14). Final carving of the plaster creates finger holds to make it easier to separate the sections (15).
10 Remove the flashing and extra clay, flip the mold over and touch up where needed. Apply oil soap to the clay and plaster surfaces to prevent the mold sections from sticking together. 11 Again place and secure aluminum flashing around the mold to prepare for pouring the middle section of the tray mold. 12 Pour plaster level with the bottom of the foot and allow it to cure. Remove the flashing.
13 Shave excess plaster off and carve a second set of round keys using a round loop tool. 14 Use a slab of clay to define where the last piece of the mold, the foot, will be poured. 15 More plaster is shaved off as the final form of the mold is refined.
Slip Casting the Tray Form
After the mold is cleaned and dried, it is filled with slip when it is upside down, without the foot section (16). This allows the tray to be finished without a drain spout. Return the extra slip to the bucket and leave approximately one cup of the slip inside the mold. The foot is placed back on the mold, all three sections are strapped together, and the mold is turned right side up (17 and 18). The extra slip left inside the mold fills in the foot. When the mold is ready to release, the foot and middle sections are removed first and the seam of the foot is finished (19). Timing is crucial at this point because the tray is full of air like a balloon. The air inside supports the walls preventing the tray from slumping. If the air is removed too early the tray can buckle in on itself, if left too long, cracks will form. I have learned to release the air slowly, letting only a small amount out at a time by plugging and unplugging a pin hole.
16 Cast the tray upside down without the bottom. 17 Place the foot section on the mold, attach the straps to keep all three sections secured together. 18 Flip the mold over, then rock it back and forth to evenly distribute the extra slip in the foot.
19 Open the mold upside down and clean the foot seam. 20 Remove the tray from the top of the mold. Begin the decoration at the leather-hard stage. Draw lines with a dull X-Acto knife. 21 Brush black underglaze over the carved lines. Let the tray dry to a stiff leather hard.
Decorating the Surface
The surfaces for the trays I have made are continuously changing. In the beginning, as I was learning how to cast the tray, I had a high loss rate. This deterred my surface decoration for a while, but having gained experience casting this form, I am now confident I will be able to see each tray through to the end. This confidence is leading me to further explore the possibilities for surfaces loosely based on quilting and Persian patterns and Islamic geometric designs. I am in search of designs I can wrap around a form and that also echo the form. The inlay pattern (20 and 21) on the newest egg trays is starting to accomplish this by repeating the rounded points of the tray ends (22).
My finished glaze palette is often bright and shiny, intended to find a place in contemporary society and add a little pomp to daily life. As those original opinions I held about slip-cast objects have been proven wrong over and over again in my studio, I am striving to find a balance between comfort and concept: between skill-based beauty and conceptual-based beauty.
the author Andrea Denniston has a BFA in ceramics from West Virginia University. During her studies, she researched traditional Chinese porcelain in Jingdezhen, China. She was a studio assistant to potter Silvie Granatelli before beginning the MFA program in ceramics at Syracuse University, in Syracuse, New York, where she currently lives and studies.