Bullseye Glass Mold #8632, Drop Out Ring 8.9"

The Drop Out Ring mold from Bullseye Glass, design number 8632, is a flat ceramic ring used for drop-out slumping. A glass sheet or fused blank is placed flat across the top of the ring so its center spans the 4.9 inch inside opening. As the kiln heats, the unsupported center of the glass softens and sinks through the opening by gravity, forming a bowl or dish shape while the outer edge rests on the ring and becomes the rim. The outer ring diameter is 8.9 inches and the ring stands 0.4 inches tall, giving it a low profile on the kiln shelf.

The mold is slipcast from a specially formulated clay body by Creative Ceramics in Europe and imported by Bullseye Glass. The surface is exceptionally smooth, accepts kiln wash uniformly, and holds up across repeated firings when used properly. Like all ceramic slumping forms, it is COE agnostic: the same mold works with COE96, COE90, or other compatible fusible glass by matching your firing schedule to the glass you are using. Because these molds are handmade, dimensions vary slightly from piece to piece, so measure your mold before cutting glass.

What does the Drop Out Ring mold make?
It shapes a flat glass sheet or fused blank into a bowl or dish by letting the softened center drop through the 4.9 inch inside opening. The depth and character of the drop depend on the slump temperature and hold time.

How does drop-out slumping work?
Place a glass sheet or blank flat across the ring so the center spans the 4.9 inch opening. As the kiln heats, gravity pulls the softened glass downward through the ring, forming the piece. The glass resting on the outer edge of the ring becomes the rim of the finished piece.

What size glass do I need?
Cut your glass to cover the ring opening with enough overlap to rest on the ring edge. The outer diameter is 8.9 inches, so a round blank close to that size works well. Because molds are handmade and vary slightly, measure your specific mold before cutting.

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?
Coat the forming surface with kiln wash or a boron nitride primer and let it dry fully before placing glass on the mold. Recoat between firings as needed.

Specifications

• SKU: 157512
• Manufacturer: Bullseye Glass (BG8632 / design 8632 / item 008632-MOLD-M-EACH; slipcast by Creative Ceramics, imported by Bullseye)
• Technique: drop-out slumping
• Outer diameter: 8.9 inches (23 cm)
• Ring height: 0.4 inches (1 cm)
• Inside opening: 4.9 inches (13 cm)
• Material: slipcast ceramic slumping form, reusable
• Glass: any COE (COE agnostic)

Working Notes

These are guidelines, not guarantees. Every kiln fires a little differently, so test a small run 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 glass on the mold so the glass does not stick.
• Place your glass flat across the top of the ring so the center spans the 4.9 inch opening. A round blank cut to the outer diameter of the ring rests securely on the ring edge and gives a clean rim on the finished piece.
• These molds are handmade by Creative Ceramics and vary slightly in size. Measure your mold before cutting glass rather than relying on the nominal 8.9 inch dimension.
• The mold is COE agnostic. Use a slumping schedule matched to your glass, adjusting the anneal soak temperature for your COE.
• Visually confirm the slump during firing when possible, and adjust the temperature or hold time if the glass has not fully formed.
• Let the kiln cool fully before removing the slumped piece. Recoat the mold surface with kiln wash or primer between firings as needed.

Bullseye Suggested Slumping Schedule

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

Segment 2 is the anneal soak at 900 F. Adjust this temperature for your glass COE if needed. Segment 4 means letting the kiln cool at its natural rate with the door closed to room temperature. Note: Bullseye's published 1250 F / 1:30 schedule for this mold is for making a shallow plate with the mold placed directly on the kiln shelf, not elevated. For a deeper drop with the mold elevated, adjust the firing and confirm the drop visually.

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

Description updated: July 6, 2026

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