Large River Rock Casting Mold

The Large River Rock Casting Mold from Creative Paradise, designed by Mark Hufford, casts two organic river rock shapes in a single firing. The larger cavity produces a finished piece measuring 3.5 inches by 2.5 inches, and the smaller cavity produces one measuring 3 inches by 2 inches. Both sit within a mold footprint of 7 inches by 5 inches, making it a practical way to cast substantial nature-themed decorative pieces, sculptural accents, or art glass components in one firing.

Like all ceramic casting molds, this one is COE agnostic. Fill the cavities with frit, billets, or stacked sheet scrap and fuse to the river rock profile. Creative Paradise lists approximately 150 grams of glass for the large cavity and 115 grams for the small cavity. The mold is reusable across many firings when properly prepped and cared for.

What does the Large River Rock mold make?
It casts two river rock shapes in one firing: a large piece at 3.5 inches by 2.5 inches and a small piece at 3 inches by 2 inches. They are well suited to decorative panels, nature-themed art glass, sculptural accents, and mixed-media projects.

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

How much glass do I need per cavity?
Creative Paradise lists about 150 grams for the large cavity and 115 grams for the small cavity. Weigh your glass and test a first run when the result matters.

How do I prep the mold before casting?
Coat each cavity with a kiln shelf primer such as a boron nitride spray (for example ZYP) or a kiln wash such as Hotline Primo Primer, and let it dry completely before adding glass. Re coat as needed between firings.

Specifications

• SKU: 168276
• Manufacturer: Creative Paradise (CPI.LF184)
• Designer: Mark Hufford
• Makes: 2 river rock shapes (1 large, 1 small)
• Large finished size: 3.5 inches L x 2.5 inches W
• Small finished size: 3 inches L x 2 inches W
• Mold size: 7 inches L x 5 inches W
• Suggested fill weight: Large 150 grams, Small 115 grams
• 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 a casting schedule suited to your glass and kiln.

• Prime each cavity with a boron nitride mold primer such as ZYP Boron Nitride Mold Primer, or a kiln wash, and let it dry completely before adding glass so the glass does not stick.
• Fill with frit, billets, or stacked sheet scrap. For a tack fired surface, Creative Paradise recommends powder and fine frit filled uniformly to about a quarter inch.
• The mold is COE agnostic. Use a full fuse schedule matched to your glass, adjusting the final anneal soak for your COE.
• Let the kiln cool fully before removing the cast pieces. Re coat the mold with primer as needed between firings.
• The Slide Hi Temp brand separator is not recommended with these molds.

Creative Paradise Suggested Firing Schedule

This is a suggested COE96 starting schedule, not a guarantee. Every kiln fires differently. Test a small run and adjust the schedule for your glass and kiln.

Full Fuse (COE96):

Tack Fire (COE96): for a tack fired surface, fill uniformly to about a quarter inch with powder and fine frit.

*Segment 4 is the anneal soak at 950 F for COE96. If using COE90, adjust this temperature to 900 F.

Helpful downloads: Basic Frit Casting Tutorial (PDF) · Fill Weights for Casting Molds (PDF) · Casting Mold Tips (PDF)

Description updated: July 6, 2026

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