Large Round Box Casting Mold

The Large Round Box Casting Mold from Colour de Verre is a two-part ceramic mold set that produces a complete round glass box with a separately cast base and lid. The two mold components measure 8 inches by 3 inches (20 by 7.5 cm) and 7 inches by 1.5 inches (17.5 by 4 cm). The finished box measures 5.5 inches by 2 inches (14 by 5 cm).

Fill the cavities with frit, billets, or sheet glass. The base cavity takes about 800 grams of glass and the lid cavity takes about 300 grams. You can also line the mold with collage glass or add frit balls, decals, or other small castings to the lid cavity for varied surface texture. Like all ceramic casting molds, this one is COE agnostic and reusable across many firings when properly primed between uses.

What does the Large Round Box Casting Mold make?
It casts a two-piece round glass box: a base and a lid. The finished box measures 5.5 inches by 2 inches (14 by 5 cm).

How much glass do I need?
Colour de Verre lists about 800 grams for the base cavity and about 300 grams for the lid cavity. Weigh your glass before loading and test a first run when the result matters, as fill weight can vary with how you pack the cavity.

What COE glass can I use in this mold?
Any COE. Ceramic casting molds are COE agnostic, so this mold works with COE96, COE90, or other fusible glass. Match your firing schedule to the specific glass you are using.

How do I prep the mold before casting?
Prime both cavities with a boron nitride mold primer before every use and let it dry completely before adding glass. Colour de Verre recommends ZYP BN Lubricoat or Hotline Primo Primer for their molds.

Specifications

• SKU: 181430
• Manufacturer: Colour de Verre
• Makes: complete round glass box (base and lid, 2 cast pieces)
• Finished piece size: 5.5 inches x 2 inches (14 x 5 cm)
• Mold component sizes: 8 x 3 inches (20 x 7.5 cm) and 7 x 1.5 inches (17.5 x 4 cm)
• Fill weight: about 800 grams (base), about 300 grams (lid)
• Material: ceramic kiln casting mold, 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 the Colour de Verre project sheet for this mold.

• Prime both mold cavities with a boron nitride mold primer before every use, and let it dry completely before adding glass so the glass does not stick. Colour de Verre recommends ZYP Boron Nitride Mold Primer or Hotline Primo Primer for their molds. Re-prime before each firing.
• Fill the base cavity with about 800 grams of glass and the lid cavity with about 300 grams. Use frit, billets, or sheet glass in either cavity.
• For varied surface effects, try lining the mold with collage glass or adding frit balls, decals, or other small castings to the lid cavity before firing.
• The mold is COE agnostic. Use a firing schedule matched to your glass and adjust the anneal soak temperature for your specific COE.
• Let the kiln cool fully before removing the cast pieces. Re-prime both cavities before the next firing.

Colour de Verre Suggested Firing Schedule

This is a suggested starting schedule, not a guarantee. Every kiln fires differently. Follow the Colour de Verre project sheet for this mold and test a small run first when the result matters.

• Heat no faster than about 350 F (195 C) per hour during the initial heat-up phase to avoid thermal shock to the mold and glass.
• Fire to no more than about 1450 F (785 C) at the top temperature for a full fuse result.
• After the top temperature soak, cool with a controlled descent and hold at the anneal point for your glass and COE before a final gradual cool to room temperature.

Helpful downloads: Large Box Mold Project (PDF) · Priming with ZYP Spray (PDF) · Tricks of the Trade (PDF)

Description updated: July 6, 2026

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