Bullseye Glass Mold #8736, Ball Surface 7.8"

The Ball Surface mold from Bullseye Glass (design #8736) is a slumping form 7.8 inches in outer diameter and 1.2 inches deep. A pre-cut fusible glass sheet or fused blank is placed over the form and heated in a kiln until the glass softens and settles into the ball surface contour by gravity. The finished piece carries the rounded ball surface profile of the mold.

The form is slipcast from a specially formulated clay body by Creative Ceramics in Europe and imported and sold by Bullseye Glass. Its surface is exceptionally smooth, accepts kiln wash uniformly, and does not crack under repeated proper use, so it holds up across many firings. The listed outer dimensions of 7.8 x 1.2 inches (20 x 3 cm) are for checking whether the mold fits your kiln. Because these forms are handmade, individual pieces vary slightly in size, so measure your mold before cutting glass.

What does this mold make?
It slumps a flat glass blank into a piece with a ball surface profile. The outer mold diameter is 7.8 inches. Measure your specific mold before cutting glass, since handmade forms can vary slightly from the nominal size.

Is this a slumping form or a casting mold?
It is a slumping form. You place a pre-made glass blank over the mold and fire it so gravity draws the glass down into the ball surface shape. There is no cavity to fill with frit or molten glass.

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

How do I prepare this 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 your glass. This keeps the glass from sticking to the mold surface. Recoat as needed between firings.

Is this mold reusable?
Yes. The slipcast clay body does not crack under repeated proper use, and the smooth surface accepts kiln wash uniformly, so it can be recoated and refired across many firings.

Specifications

• SKU: 152522
• Manufacturer: Bullseye Glass (made by Creative Ceramics, imported by Bullseye Glass)
• Design number: #8736 (item number 008736-MOLD-M-EACH; store model code BG8736)
• Outer dimensions: 7.8 x 1.2 in (20 x 3 cm)
• Material: slipcast clay, reusable slumping form
• Surface: exceptionally smooth, accepts kiln wash uniformly
• 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.
• Lay your pre-cut glass blank or fused piece over the mold. Measure your specific mold before cutting glass, since handmade forms vary slightly from the nominal 7.8 inch outer diameter.
• The mold is COE agnostic. Use a slumping schedule matched to your glass, adjusting the anneal soak temperature for your COE (about 900 F for COE90, 950 F for COE96).
• Slump at the lowest temperature that fully forms the glass. Visually confirm the slump during firing and do not over-fire.
• Let the kiln cool fully before removing the piece. Recoat the mold surface with kiln wash as needed between firings.

Bullseye Suggested Slumping Schedule

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

*AFAP means as fast as possible (the kiln drops at its natural rate with no ramp limit). Segment 2 is the anneal soak at 900 F, suited to COE90 glass. If using COE96, adjust the anneal soak to 950 F. Segment 4 is a natural cool to room temperature with the kiln door closed.

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

Description updated: July 6, 2026

Spot an error or have feedback on this description? Report it here.