Bullseye Glass Mold #8746, Ball Surface 5.8"

The Ball Surface mold from Bullseye Glass (design number 8746) is a ceramic slumping form that curves a flat glass sheet or fused blank into a smooth ball surface shape. It is slipcast from a specially formulated clay body by Creative Ceramics in Europe and imported by Bullseye Glass. The exceptionally smooth surface accepts kiln wash uniformly and does not crack under repeated proper use.

The outer dimensions are 5.8 inches by 1.7 inches (15 by 4 cm). These dimensions indicate how much space the mold occupies in your kiln, not the cut size of your glass blank. Because the molds are handmade and can vary slightly in size, measure the actual mold before cutting glass. Like all ceramic slumping forms, it is COE agnostic and reusable across many firings with proper care.

What does the Ball Surface mold make?
It slumps a flat glass sheet or fused blank into a curved ball surface form, roughly 5.8 inches across. The finished piece can serve as a decorative plate, bowl blank, or focal accent depending on how it is used and finished.

How does slumping work with this mold?
A pre-cut glass blank is placed on or into the mold on a kiln shelf. As the kiln heats, the glass softens and gravity draws it down to conform to the ball surface curve. The outer mold size (5.8 by 1.7 inches) indicates the space the form occupies in the kiln. Cut your glass blank to the finished size you want, and measure the actual mold before cutting because handmade molds vary slightly in size.

What COE glass can I use?
Any COE. Ceramic slumping forms are COE agnostic, so the same mold works with COE96, COE90, or other fusible glass. Match your firing schedule and anneal soak temperature to the glass you are using.

How do I prep the mold before slumping?
Coat the forming surface with kiln wash or a boron nitride primer and let it dry completely before setting glass on the mold. Recoat as needed between firings.

Specifications

• SKU: 152347
• Manufacturer: Bullseye Glass (made by Creative Ceramics, Europe; store code BG8746, design number 8746, item number 008746-MOLD-M-EACH)
• Shape: ball surface curve
• Outer mold size: 5.8 x 1.7 in (15 x 4 cm)
• Note on sizing: molds are handmade and vary slightly; measure the actual mold before cutting glass
• Material: slipcast ceramic kiln slumping form, reusable
• Surface: exceptionally smooth, accepts kiln wash uniformly
• Glass: 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, mold depth, 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 fully before setting glass on the mold.
• Cut your glass blank to the finished size you want, not to the outer mold dimension. Measure the actual mold before cutting because handmade molds vary slightly in size.
• Place the prepared glass on or into the mold on a level kiln shelf. Slump at the lowest temperature that fully forms the glass, confirm the slump visually during firing, and anneal thoroughly.
• The mold is COE agnostic. Adjust the anneal soak temperature for your glass: about 900 F for COE90 or 950 F for COE96.
• Let the kiln cool fully before removing the slumped piece. Recoat the mold with kiln wash as needed between firings.

Bullseye Suggested Slumping Schedule

This is a suggested starting schedule based on slumping 6mm pieces in a Paragon GL24 kiln, not a guarantee. Every kiln fires differently. Visually confirm the slump during firing and adjust the schedule for your glass, mold depth, and kiln.

AFAP means as fast as possible. For Segment 4, let the kiln cool to room temperature at its natural rate with the door closed. For COE96 glass, adjust the anneal soak in Segment 2 to 950 F. For COE90, use 900 F as shown. Always follow Bullseye's published Suggested Slumping Schedule for your specific glass and kiln, and test a small piece first.

Helpful downloads: Suggested Slumping Schedules from Bullseye Glass (PDF)

Description updated: July 6, 2026

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