CNC, Jeannie Wu, Positive, Yasemin Uyar, Ceramics, Diego Sinbert
Mold making, Pieluigi Pompei
Special thanks to the Sundaymorning@EKWC for their encouragement and expertise.
The design of the T-stool originates from an interest in the traditional Chinese ceramic tea stool. These stools are based upon a hollow vessel, often cylindrical in form, which is strong in compression. Alternatively, the T-Stool’s stability originates from the plasticity of a folded convex surface and its transformation into a hollow ceramic shell, approximately 1.5 cm thick (100 cm l. x 60 cm h. x 70 cm w.). While it is strong in compression the folded surface introduces stresses that are typically avoided when working with ceramic due to its low tensile strength. A special clay recipe was developed in response to these characteristics. The high degree of surface curvature provides additional strength during firing and each fold creates opportunities for complex reflections. The use of metallic luster and the crackle patterns that develop in response to the surface stresses between the clay and the glaze, provide each stool with its specificity.
A two part mold was designed to allow the clay to be pressed into the form. A 3 mm rubber membrane was constructed over the entire surface to insure its release from the mold. The mold has been used to produce three unique versions of the T-Stool. The use of rubber molds with ceramics is a recent development due to the fact that the rubber impedes the clays ability to cure. Once a layer of clay is pressed inside the mold to the desired thickness, the mold is removed, piece by piece, over several days.
- T-Stool, Ceramic prototype, 3-3. 100 cm l. x 60 cm h. x 70 cm w. Materials: Press molded stoneware, with matte white glaze. EKWC 2012.
- Form testing through complexly folded surface. EKWC 2011.
- Digital wire-frame model of final design. EKWC 2011.
- From Left to right: An animation sequence of the rigid foam parts for one quarter of the T-Stool. A positive is assembled from 30 milled, urethane parts, roughly 2” deep. The positive was sealed and used to make the rubber mold. EKWC 2011
- The two part rubber mold prior to assembly. The mold consists of 14 rubber parts and 30 epoxy components. A two part mold is required to provide a rigid surface for the pressing of the clay into the mold. The interior of the mold consists of a 3 mm thick urethane rubber layer surrounded by a 5mm two part epoxy mother-mold. In order for the rubber to be poured evenly a 3 mm layer of wet clay is modeled on top of the positive. Following this a waterproof film is laid up on top of the clay and the epoxy mold is pressed on top of the film. Once the epoxy cures the clay is removed and the mother mold is then used as a cavity to pour in the liquid rubber. EKWC 2011.
- A view inside one half of the mold. Roughly 150 kg of clay is pressed into the mold by hand. The surface is covered from the inside to a thickness of 1.5 cm by laying up 1.7 cm thick slabs. A special pressing technique was developed to maintain a uniform thickness and eliminate any visible seams on the finished surface. EKWC 2012.
- Rigging required to manoeuver mold packed with 150kg of clay. The clay is pressed in from the bottom leaving a 1.5 cm continuous clay surface. After several days the clay reaches the leather-hard state and the mold is then suspended in stirrups and rotated 180 degrees into the upright position. The mold is designed to be disassembled from the top to the bottom and to provide support for the clay as the mold is removed. While the rubber mold retains considerably more moisture than plaster it has added benefits. The rubber can be removed in areas with significant undercuts, by first taking away the rigid mold and then peeling off or collapsing the rubber. EKWC 2011.
- The mold in the upright position. EKWC 2011.
- Detail of joints between rigid epoxy mold parts. EKWC 2011.
- Form removed from mold. EKWC 2012.
- Kiln loading prior glaze firing. EKWC 2012.
- After glaze firing. EKWC 2012.
- EKWC 2012.