Bullseye Glass Mold #8735, Ball Surface 9.4"

The Ball Surface mold from Bullseye Glass (design #8735) is a slipcast ceramic slumping form that measures 9.4 inches across and 2 inches tall. A flat glass sheet or fused blank is placed over or set into the form, then heated in the kiln so the softened glass takes the rounded ball surface contour by gravity.

Made by Creative Ceramics in Europe and imported by Bullseye Glass, the form is slipcast from a specially formulated clay body that produces an exceptionally smooth surface and accepts kiln wash uniformly. It is reusable across many firings with proper care and preparation. The listed outer dimensions help you confirm kiln fit, but because these forms are handmade, individual pieces vary slightly in size, so measure your mold before cutting glass.

What does the Ball Surface mold make?
It slumps a flat glass sheet or fused blank into a rounded ball surface curve, with an outer dimension of about 9.4 inches. The result is a curved glass piece shaped by the ball contour of the form.

What glass can I use 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 to the glass you are using.

How do I prepare 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 fully before placing glass. The smooth slipcast surface accepts kiln wash uniformly. Recoat as needed between firings.

How do I size my glass for this mold?
The 9.4 inch measurement is the outer dimension of the mold, not the size of the glass blank you need. Measure your mold directly before cutting glass, as these handmade forms vary slightly from piece to piece.

Specifications

• SKU: 152851
• Manufacturer: Bullseye Glass (made by Creative Ceramics; design #8735, item 008735-MOLD-M-EACH, store code BG8735)
• Form type: ball surface slumping form
• Outer dimensions: 9.4 in x 2 in (24 cm x 5 cm)
• Note on sizing: molds are handmade and vary slightly; measure before cutting glass
• 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 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 before placing glass. You may also prime with a boron nitride spray such as ZYP Boron Nitride Mold Primer. Let the coating dry fully before placing glass so the glass does not stick.
• The 9.4 inch outer dimension is the mold's outside edge. Measure the mold directly before cutting glass, as these handmade forms vary slightly in size.
• The mold is COE agnostic. Adjust the anneal soak temperature for your glass: about 900 F for COE90 or 950 F for COE96.
• Ramp slowly and visually confirm the slump is complete before beginning the cool-down.
• Let the kiln cool fully before removing the slumped piece. Recoat the mold with kiln wash or primer 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 and glass styles vary in viscosity. Visually confirm the slump during firing and adjust the schedule for your glass and kiln.

AFAP means as fast as possible (let the kiln drop at its natural rate, door closed). The anneal soak in segment 2 is listed at 900 F, which suits Bullseye COE90 glass. If using COE96 glass, raise the anneal soak to about 950 F.

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

Description updated: July 6, 2026

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