The Round Tray mold from Bullseye Glass (design number 8781) slumps a sheet of fusible glass into a shallow round form about 5.25 inches across. Placed over the mold in the kiln, the glass softens and settles into the tray shape under gravity, yielding a small round dish suitable for jewelry, small objects, or decorative use.
The mold is slipcast from a specially formulated clay body by Creative Ceramics in Europe, then imported and sold by Bullseye Glass. The surface is exceptionally smooth, accepts kiln wash uniformly, and holds up well to repeated proper use. Bullseye lists outer mold dimensions of 5.4 x 1 inches (14 x 2.5 cm) as the measurement used to confirm kiln fit; because these molds are handmade they vary slightly in size, so measure your mold before cutting glass.
What does this mold make?
What size glass blank do I need?
What COE glass can I use?
How do I prep the mold before slumping? Hotline Primo Primer and let it dry completely before placing your glass. Re-coat as needed between firings so the finished piece releases cleanly.
Specifications
SKU: 172207Manufacturer: Bullseye Glass (made by Creative Ceramics, imported by Bullseye); store code BG8781, Bullseye design #8781, Bullseye item 008781-MOLD-M-EACHMakes: 1 shallow round trayFinished piece size: about 5.25 inches acrossOuter mold size: 5.4 inches x 1 inch (14 x 2.5 cm) (for kiln fit; handmade, measure before cutting glass)Material: slipcast clay slumping form, reusableGlass: any COE (COE agnostic)
Working Notes
These are guidelines, not guarantees. Every kiln fires a little differently, so test a small piece first when the result matters and follow a slumping schedule suited to your glass and kiln.
Coat the forming surface with kiln wash or a boron nitride mold primer such as ZYP Boron Nitride Mold Primer and let it dry completely before placing your glass so the finished piece releases cleanly.
Bullseye's outer mold dimensions of 5.4 x 1 inches (14 x 2.5 cm) are the measurement used to check kiln fit. These molds are handmade and vary slightly in size; measure your mold before cutting your glass blank.
The mold is COE agnostic. Match your firing schedule and anneal soak to your glass: about 900 F for COE90, about 950 F for COE96.
Let the kiln cool fully before removing the slumped piece. Re-coat the forming surface with kiln wash or primer as needed between firings.
Bullseye Suggested Slumping Schedule (starting point)
This is a suggested starting schedule based on Bullseye's published slumping guidance, not a guarantee. Every kiln fires differently. Follow Bullseye's published Suggested Slumping Schedule for your glass and mold depth, visually confirm the slump, and test a small piece first.
Ramp at about 300 F per hour to the slump process temperature.
Slump temperature: use the lowest temperature that fully forms the glass into the tray shape. Bullseye's published starting point for this mold is 1225 F, though very shallow forms may slump fully at cooler temperatures.
Hold at the slump temperature for about 1 hour (Bullseye's published hold for this mold), or until the glass has fully settled into the form.
Cool as fast as possible (AFAP) to the anneal soak: about 900 F for COE90, about 950 F for COE96. Hold the anneal soak for about 1 hour.
Cool at about 100 F per hour from the anneal soak down to 700 F, then cool to room temperature with the kiln door closed.
Helpful downloads: Suggested Slumping Schedules from Bullseye Glass (PDF)
Description updated: July 6, 2026
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