Inspiration can come from unexpected experiences. In a porcelain workshop at Penland School of Craft with Leah Leitson and Susan Filley, I was encouraged to focus on my detailed surface designs by slip casting my forms—a technique I had long wanted to learn. This feedback led me to a residency at the Guldagergaard International Ceramic Research Center in Denmark, where I taught myself to make molds for efficient shape replication.
Clay Play
Creating a clay prototype will serve as the original model from which the mold will be made. Choose a grog-free clay body suitable for sculpting. Before you begin, conceptualize the design of the handle. Use reference photos, physical objects, and original sketches to determine details including size, scale, curvature, taper, and how many fingers the handle can accommodate.
Start with a clay lug larger than the design, bending it into the desired curve. Let it firm up until it can hold its shape, but it is not yet leather hard. Sculpt the basic shape and volume, continuously referring to the reference materials to guide proportions and scale. Allow the prototype to dry to leather hard. Refine the form with a serrated metal rib by carving away and smoothing the clay to shape the finer details. Make sure to check for symmetry periodically to maintain balance and uniformity. Once you are satisfied with the overall shape, give the entire prototype a final smooth (1). Note: The final cast will capture any surface texture left on the model.
Prepping the Mold
For mug handles, a two-part plaster mold is used, with a seam running along the least visible part of the handle to minimize post-casting finishing work. The mold should be designed to allow easy removal of the cast piece without damaging the shape or getting stuck on an undercut. Trace the parting line with a black Sharpie marker, bisecting the handle lengthwise on its exterior and interior (2).
Embed the handle into a slab of clay leaving at least 1 inch (2.5 cm) of space around it in all directions (3). Next, smooth out the clay surface around the handle and add registration keys in the clay around the object (see 4). These will help align the two mold halves accurately once you go to cast it.
Arrange the cottle boards around the clay block and prototype locking them into place with four clamps (4). Apply a thin layer of mold release over the entire interior of the cottled area to prevent the plaster from sticking to the cottle boards, walls, or plaster if making multiple-mold parts. To mix a mold release, combine 1 part Murphy’s Oil Soap to 1 part water. Brush it on, then smooth out the area to be cast (5). The plaster will capture any texture or air bubbles, even from the mold release.
Plaster Party
To calculate how much plaster and water to mix, refer to the Water-to-Plaster Ratio Chart (below). Wearing a properly fitted respirator, weigh out the plaster and water in separate buckets on a zeroed-out gram scale. Then, add plaster to the water, breaking up any chunks—the material should be powdery. Make sure to work consistently and quickly because once the plaster is in the water it will slowly start to set up. Slake for 1–3 minutes, tapping the bucket to release air bubbles. Start mixing continuously for 7 minutes. Note: Don’t mix too vigorously, as this can introduce air. When the plaster thickens and a finger trace line stays put, it is ready to pour.
Pour the plaster against your hand into the mold set up to let the plaster roll down into the mold (6). Tap the table to release air bubbles from the plaster. Tip: Avoid tapping the mold setup as it may dislodge a cottle or cause a leak.
Unlock the clamps and remove the cottle boards once the plaster has warmed and cooled, about 45 minutes. Then, gently remove the clay, leaving the prototype embedded in the first half of the plaster mold (7). Remove any clay residue from the plaster surface and encase the first half in cottle boards and clamps with the exposed handle side up. Repeat the process of measuring, mixing, and pouring over the first part of the handle mold.
De-mold the handle prototype using the same cure time. Gently pull the mold halves, extracting the handle from the mold. Next, clean up the mold using a metal rib or Surform to round sharp edges that may flake plaster into your work. Dry the mold for 1–2 days before use.
Repeat the entire process to create variations of handles, giving your work more depth and creativity (8).
Color Copies
Pigmenting casting slip with ceramic stains adds color to the handle without extra glazing steps. Make sure to test new molds with plain slip first to avoid plaster contamination. For small attachments like handles, I recommend casting solid instead of hollow as in traditional slip casting.
Mold making has a steep learning curve that requires patience and persistence. Embracing this journey can save valuable time and lead to a deeper understanding of your craft, making the effort well worth it in the end.
Adrienne Eliades lives and maintains a studio in Vancouver, Washington. She is the H.O.T. CLAY program coordinator for Idyllwild Arts Summer Program in Idyllwild, California, and teaches workshops nationwide. See more of her work at www.adrienneeliades.com.
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Inspiration can come from unexpected experiences. In a porcelain workshop at Penland School of Craft with Leah Leitson and Susan Filley, I was encouraged to focus on my detailed surface designs by slip casting my forms—a technique I had long wanted to learn. This feedback led me to a residency at the Guldagergaard International Ceramic Research Center in Denmark, where I taught myself to make molds for efficient shape replication.
Clay Play
Creating a clay prototype will serve as the original model from which the mold will be made. Choose a grog-free clay body suitable for sculpting. Before you begin, conceptualize the design of the handle. Use reference photos, physical objects, and original sketches to determine details including size, scale, curvature, taper, and how many fingers the handle can accommodate.
Start with a clay lug larger than the design, bending it into the desired curve. Let it firm up until it can hold its shape, but it is not yet leather hard. Sculpt the basic shape and volume, continuously referring to the reference materials to guide proportions and scale. Allow the prototype to dry to leather hard. Refine the form with a serrated metal rib by carving away and smoothing the clay to shape the finer details. Make sure to check for symmetry periodically to maintain balance and uniformity. Once you are satisfied with the overall shape, give the entire prototype a final smooth (1). Note: The final cast will capture any surface texture left on the model.
Prepping the Mold
For mug handles, a two-part plaster mold is used, with a seam running along the least visible part of the handle to minimize post-casting finishing work. The mold should be designed to allow easy removal of the cast piece without damaging the shape or getting stuck on an undercut. Trace the parting line with a black Sharpie marker, bisecting the handle lengthwise on its exterior and interior (2).
Embed the handle into a slab of clay leaving at least 1 inch (2.5 cm) of space around it in all directions (3). Next, smooth out the clay surface around the handle and add registration keys in the clay around the object (see 4). These will help align the two mold halves accurately once you go to cast it.
Arrange the cottle boards around the clay block and prototype locking them into place with four clamps (4). Apply a thin layer of mold release over the entire interior of the cottled area to prevent the plaster from sticking to the cottle boards, walls, or plaster if making multiple-mold parts. To mix a mold release, combine 1 part Murphy’s Oil Soap to 1 part water. Brush it on, then smooth out the area to be cast (5). The plaster will capture any texture or air bubbles, even from the mold release.
Plaster Party
To calculate how much plaster and water to mix, refer to the Water-to-Plaster Ratio Chart (below). Wearing a properly fitted respirator, weigh out the plaster and water in separate buckets on a zeroed-out gram scale. Then, add plaster to the water, breaking up any chunks—the material should be powdery. Make sure to work consistently and quickly because once the plaster is in the water it will slowly start to set up. Slake for 1–3 minutes, tapping the bucket to release air bubbles. Start mixing continuously for 7 minutes. Note: Don’t mix too vigorously, as this can introduce air. When the plaster thickens and a finger trace line stays put, it is ready to pour.
Pour the plaster against your hand into the mold set up to let the plaster roll down into the mold (6). Tap the table to release air bubbles from the plaster. Tip: Avoid tapping the mold setup as it may dislodge a cottle or cause a leak.
Unlock the clamps and remove the cottle boards once the plaster has warmed and cooled, about 45 minutes. Then, gently remove the clay, leaving the prototype embedded in the first half of the plaster mold (7). Remove any clay residue from the plaster surface and encase the first half in cottle boards and clamps with the exposed handle side up. Repeat the process of measuring, mixing, and pouring over the first part of the handle mold.
De-mold the handle prototype using the same cure time. Gently pull the mold halves, extracting the handle from the mold. Next, clean up the mold using a metal rib or Surform to round sharp edges that may flake plaster into your work. Dry the mold for 1–2 days before use.
Repeat the entire process to create variations of handles, giving your work more depth and creativity (8).
Color Copies
Pigmenting casting slip with ceramic stains adds color to the handle without extra glazing steps. Make sure to test new molds with plain slip first to avoid plaster contamination. For small attachments like handles, I recommend casting solid instead of hollow as in traditional slip casting.
Mold making has a steep learning curve that requires patience and persistence. Embracing this journey can save valuable time and lead to a deeper understanding of your craft, making the effort well worth it in the end.
Adrienne Eliades lives and maintains a studio in Vancouver, Washington. She is the H.O.T. CLAY program coordinator for Idyllwild Arts Summer Program in Idyllwild, California, and teaches workshops nationwide. See more of her work at www.adrienneeliades.com.
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