Bullseye Glass Mold #8647, Square Bowl Simple Curve 12"

The Square Bowl Simple Curve 12 inch mold from Bullseye Glass (design number 8647) is a slumping form for producing a 12 inch square bowl with a gentle, shallow curve. A pre-cut glass sheet or fused blank is placed over the form and heated slowly until the glass softens and settles onto the surface by gravity, taking on the mold's simple curved profile.

The mold is slipcast from a specially formulated clay body by Creative Ceramics in Europe and imported by Bullseye Glass. The forming surface is exceptionally smooth, accepts kiln wash uniformly, and will not crack under repeated proper use. The outer mold footprint is 12 inches by 12 inches by 2.5 inches tall (31 by 31 by 6 centimeters), which you can use to confirm the mold will fit in your kiln before firing. Because these molds are handmade, individual pieces vary slightly in size; measure your mold before cutting your glass blank.

What does the Square Bowl Simple Curve 12 inch mold make?
It forms a 12 inch square glass bowl with a soft, simple curve. A flat glass sheet or fused blank is placed over the form and fired until gravity settles the glass into the bowl shape.

Does it work with any COE glass?
Yes. Like all ceramic slumping forms, this mold is COE agnostic. Use it with COE90, COE96, or other fusible glass, and match your firing schedule to the glass you are using.

How do I prep the mold before slumping?
Coat the forming surface with a kiln wash such as Hotline Primo Primer or a shelf primer and let it dry completely before placing your glass. The smooth slipcast surface accepts kiln wash uniformly, which helps the finished piece release cleanly after firing.

How do I size my glass blank for this mold?
The outer mold dimensions are 12 by 12 by 2.5 inches (31 by 31 by 6 centimeters). Because these molds are handmade and vary slightly in size, measure your specific mold directly before cutting your glass blank rather than relying solely on the nominal dimensions.

Specifications

• SKU: 152810
• Manufacturer: Bullseye Glass (design #8647, item 008647-MOLD-M-EACH; made by Creative Ceramics in Europe, imported by Bullseye Glass)
• Store model code: BG8647
• Makes: 12 inch square bowl with simple curve
• Mold outer dimensions: 12 x 12 x 2.5 in (31 x 31 x 6 cm)
• Material: slipcast ceramic, 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 shelf primer such as ZYP Boron Nitride Mold Primer and let it dry completely before placing your glass. The mold's smooth surface accepts kiln wash uniformly.
• Place a pre-cut flat glass sheet or fused blank on top of the form. Because molds are handmade and vary slightly in size, measure your mold directly before cutting your blank.
• 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 if possible, and do not rush the cool-down. Let the kiln cool fully before removing the slumped piece.
• Re-coat the forming surface with kiln wash as needed between firings.

Bullseye Suggested Slumping Schedule

This is a suggested starting schedule based on slumping 6 mm 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.

Segment 2 is the anneal soak at 900 F, suited to COE90 glass. If using COE96, adjust this soak to 950 F. Segment 4 (AFAP to 70 F) means letting the kiln cool at its natural rate with the door closed until it reaches room temperature.

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

Description updated: July 6, 2026

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