Bullseye Glass Mold #8899, Square Plate, Simple Curve Slumper 6.3"

The Square Plate Simple Curve Slumper from Bullseye Glass (design number 8899) is a ceramic slumping form that shapes a flat or fused glass blank into a gently curved square plate. A pre-cut glass sheet is laid over the smooth forming surface, then fired in the kiln until the glass softens and settles into a shallow, even curve by gravity.

The outer mold dimensions are 6.3 by 6.3 by 0.9 inches (16 by 16 by 2 cm). These are the outer dimensions used to check kiln fit. Because the forms are handmade, each one varies slightly in size, so measure your specific mold before cutting your glass blank. 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 under repeated proper firings.

What does the Bullseye #8899 mold make?
It slumps a glass blank into a gently curved square plate, approximately 6.3 inches across. The shallow single curve gives the finished piece a clean square plate profile.

What size glass blank do I need for this mold?
The outer mold footprint is 6.3 by 6.3 inches, but these forms are handmade and vary slightly in size. Measure your specific mold before cutting glass. Size your blank to fit the forming surface, not the outer dimension of the mold.

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

How do I prep and use this mold?
Coat the forming surface with kiln wash or a boron nitride primer and let it dry completely. Then set your flat or fused glass blank on top of the form and fire to the slump temperature. The glass softens and drapes over the surface by gravity. Let the kiln cool fully before removing the piece.

Specifications

• SKU: 4479
• Manufacturer: Bullseye Glass (made by Creative Ceramics, BG8899 / design number 8899)
• Makes: one curved square plate per firing
• Outer mold size: 6.3 x 6.3 x 0.9 in (16 x 16 x 2 cm)
• Note: molds are handmade and vary slightly in size; measure before cutting glass
• Material: slipcast clay body, made by Creative Ceramics in Europe, imported by Bullseye Glass, 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.

• Measure your mold before cutting glass. The outer dimension of 6.3 by 6.3 inches is for checking kiln fit only. The handmade forming surface may vary slightly, so measure it directly.
• 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 the glass.
• Place your pre-cut flat or fused glass blank on top of the prepared form. The glass slumps over the surface by gravity as it heats. Do not fill it as you would a casting mold.
• This mold is COE agnostic. Adjust the anneal soak temperature in your schedule for your glass: about 900 F for COE90 or 950 F for COE96.
• Visually confirm the slump during firing if your kiln allows it. Let the kiln cool fully before removing the finished piece. Recoat the forming surface with kiln wash between firings as needed.

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 and glass styles vary in viscosity. Follow Bullseye's published Suggested Slumping Schedule for your glass and mold, visually confirm the slump during firing, and test a small piece first.

*AFAP means as fast as possible: let the kiln drop at its natural rate. For segment 4, keep the door closed and let the kiln cool to room temperature on its own. Segment 2 is the anneal soak; the 900 F target suits COE90 glass. For COE96, raise the anneal soak to 950 F.

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

Description updated: July 6, 2026

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