The Medium River Rocks mold from Creative Paradise is a frit casting mold designed by Mark Hufford that produces river rock shapes ranging from 1.25 to 1.5 inches long in a single firing. The mold measures 6.5 inches long by 6 inches wide with a 1.5 inch depth, giving each cast rock a solid, natural profile well suited to decorative work, mosaic accents, and jewelry applications.
Like all ceramic casting molds, this one is COE agnostic. Load each cavity with frit, small billets, or stacked sheet scrap and fire to a full fuse or tack fire to cast the rock shapes. Creative Paradise lists a fill weight of 18 to 20 grams per rock. The mold is reusable across many firings when prepped and cared for properly.
What does the Medium River Rocks mold make?
It casts glass river rock shapes, each ranging from 1.25 to 1.5 inches long, in a single firing. The rocks suit decorative use, mosaic work, and jewelry accents.
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 rock?
Creative Paradise lists 18 to 20 grams per rock. Fill weight varies with how full you want each cavity, so weigh your glass and test a first run when the result matters.
How do I prep the mold before casting?
Coat the cavities 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: 167112
- Manufacturer: Creative Paradise (CPI.LF180)
- Designed by: Mark Hufford
- Makes: river rock shapes per firing
- Finished piece size: 1.25 to 1.5 inches long each
- Mold size: 6.5 inches L x 6 inches W x 1.5 inches deep
- Suggested fill weight: 18 to 20 grams per rock
- 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 the cavities 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 each cavity with frit, small billets, or stacked sheet scrap. For a tack fired surface, Creative Paradise recommends using 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 rocks. 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):
| Segment |
Rate |
Temp (F) |
Hold |
| 1 |
300 |
1150 |
45 |
| 2 |
150 |
1300 |
20 |
| 3 |
400 |
1460 |
10 |
| 4 |
9999 |
950* |
60 |
Tack Fire (COE96): for a tack fired surface, fill uniformly to about a quarter inch with powder and fine frit.
| Segment |
Rate |
Temp (F) |
Hold |
| 1 |
300 |
1150 |
45 |
| 2 |
150 |
1300 |
20 |
| 3 |
400 |
1410 |
10 |
| 4 |
9999 |
950* |
60 |
*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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