Bullseye Glass Mold #8900, Square Plate, Simple Curve Slumper 5.3"

The Bullseye Glass Mold #8900 is a square plate slumper with a simple curve. A pre-cut glass blank or fused piece is placed over the form, and as the kiln heats the glass softens and settles by gravity into the gentle curve of the form below. The result is a small square plate with a soft, even curve across its face. The mold outer footprint is 5.3 inches by 5.3 inches by 1 inch tall (13 by 13 by 3 centimeters), a compact size that fits most kilns.

Slipcast from a specially formulated clay body by Creative Ceramics in Europe and imported by Bullseye Glass, the form has an exceptionally smooth surface that accepts kiln wash uniformly and does not crack under repeated proper use. It is reusable across many firings when prepped and cared for properly.

What does Bullseye Mold #8900 make?
It slumps a glass blank into a square plate with a gentle, simple curve. The glass is placed over the form and fires to the mold's shape by gravity.

What size glass do I cut for this mold?
The mold outer footprint is 5.3 inches by 5.3 inches. Because these forms are handmade and vary slightly in size, measure your specific mold before cutting glass and allow room for the glass to move as it slumps.

What COE glass works with this mold?
Any COE. Ceramic slumping forms are COE agnostic, so the same mold works with COE90, COE96, or other fusible glass. Match your firing schedule to the glass you are using.

How do I prep the mold before firing?
Coat the forming surface with a kiln wash such as Hotline Primo Primer or a shelf primer and let it dry completely before placing glass. The surface accepts kiln wash uniformly. Re-coat as needed between firings.

Specifications

• SKU: 3659
• Manufacturer: Bullseye Glass (BG8900; design number 8900; item number 008900-MOLD-M-EACH)
• Makes: square plate with simple curve
• Mold outer dimensions: 5.3 x 5.3 x 1 in (13 x 13 x 3 cm)
• Material: slipcast ceramic, made by Creative Ceramics in Europe, imported by Bullseye Glass
• Surface: exceptionally smooth, accepts kiln wash uniformly
• Technique: slumping and draping
• 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 and kiln.

• Coat the forming surface with kiln wash or a shelf primer such as ZYP Boron Nitride Mold Primer, and let it dry completely before placing glass so the slumped piece releases cleanly.
• The mold outer footprint is 5.3 by 5.3 inches. These forms are handmade and vary slightly in size, so measure your mold before cutting glass.
• Place a pre-cut blank or fused piece over the form. The glass softens and settles into the curve by gravity as the kiln heats.
• The mold is COE agnostic. Use a slumping schedule matched to your glass, adjusting the anneal soak temperature for your COE.
• Let the kiln cool fully before removing the slumped piece. Re-coat 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, not a guarantee. Every kiln fires differently. Visually confirm the slump during firing and adjust the schedule for your glass, kiln, and mold depth.

AFAP means the kiln cools without a programmed rate limit for that segment. The anneal soak at 900 F is suited to COE90 glass (Bullseye). If you are using COE96 glass, adjust the anneal soak temperature to approximately 950 F. Segment 4 lets the kiln cool to room temperature at its natural rate, door closed.

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

Description updated: July 6, 2026

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