The Classic Slumping Mold #8723 from Bullseye Glass is a rectangular slumping form with outer dimensions of 12.1 inches by 3 inches (31 by 8 cm). A pre-cut or pre-fused glass blank is placed over or into the form, then fired slowly until the glass softens and settles into the mold shape by gravity. The slipcast ceramic surface is exceptionally smooth, accepts kiln wash uniformly, and does not crack under repeated proper use.
The mold is made by Creative Ceramics in Europe using a specially formulated clay body, and imported and sold by Bullseye Glass. The listed outer dimensions are provided for kiln fit planning. Because these molds are handmade, individual pieces may vary slightly in size, so measure your mold before cutting your glass blank. Like all ceramic slumping forms, it is COE agnostic and reusable across many firings when properly prepped and maintained.
What does the Classic Slumping Mold #8723 make?
How do I know if this mold fits my kiln?
What COE glass can I use with this mold?
How do I prep the mold before slumping?
Specifications
SKU: 159914Manufacturer: Bullseye Glass (design #8723, item 008723-MOLD-M-EACH; slipcast by Creative Ceramics in Europe, imported by Bullseye)Store model code: BG8723Outer dimensions: 12.1 inches x 3 inches (31 x 8 cm)Note: Molds are handmade and may vary slightly in size; measure your mold before cutting glassMaterial: ceramic slumping form, slipcast, reusableSurface: exceptionally smooth, accepts kiln wash uniformly, does not crack under repeated proper useGlass: 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, kiln, and mold depth.
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 your glass blank.
These molds are handmade. Measure your individual mold before cutting glass to account for natural size variation.
Place your glass sheet or fused blank over or into the form. Visually confirm the slump is complete during firing. Do not open the kiln until it has cooled fully.
The mold is COE agnostic. Use a slumping schedule matched to your glass, and adjust the anneal soak temperature for your COE.
Re-coat the mold surface with kiln wash between firings as needed.
Bullseye Suggested Slumping Schedule
This is Bullseye's suggested starting schedule for slumping 6mm pieces in a Paragon GL24, not a guarantee. Every kiln fires differently. Visually confirm the slump during firing and adjust for your glass, kiln, and mold depth.
Segment Rate (F/hr) Temp (F) Hold 1 (slump ramp) 300 1225 45 min 2 (anneal soak) AFAP 900 60 min 3 (anneal cool) 100 700 none 4 (final cool) AFAP 70 none
AFAP means as fast as possible; the kiln drops to that temperature at its natural rate with the door closed. Segment 2 anneals at 900 F, which suits COE90. If using COE96, adjust the anneal soak to about 950 F. Let the kiln cool fully to room temperature before opening.
Helpful downloads: Suggested Slumping Schedules from Bullseye Glass (PDF)
Description updated: July 6, 2026
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