System

Stone Mosaic Casting System

Place each piece — stone mosaic set in gypsum for patterns you design yourself.

Coverage 1 m² per 5 kg

Cure Time Cures in 24–48 h

Skill Level Beginner-friendly

Specifications, explained

The numbers that decide how a cast behaves — and what to watch for at each step.

Base Grouting gypsum + stone mosaic chips: Harder than pottery plaster, so thin walls survive demoulding without chipping.
Chips Natural stone chips — 6–12 mm coasters, 8–15 mm tray: Chips are laid dry before any grout is poured, so the pattern is decided up front.
Mix ratio Gypsum : water = 100 : 40 by weight: Too much water costs strength and leaves a chalky surface. Weigh it, do not eyeball it.
Batch yield 950 g → 4 coasters · 1,500 g → one 25 × 18 cm tray: The tray casting set is sized for one 25 × 18 cm tray; the coaster casting set fills four round cavities.

Working time 15–20 minutes to lay the chips: Past that the mix thickens and stops flowing into fine detail.
Demould 25 min coasters · 30 min tray: Too early and the edges slump; too late and the piece fights the mould.
Full cure 24 h — handling strength in 6–8 h: Handling strength comes early, but sealing and load-bearing should wait a full day.
Sealing Once fully dry, dip in the polyurethane sealer for 20–30 s, then air-dry: The dipped coat cures into a glossy protective layer.

Surface relief Chips sit 1–2 mm proud of the grout: That relief is what reads as stone rather than a printed pattern.
Surface Matte · P2500 (2000-grit) edges · PU sealed: Sealing locks the aggregate in and stops oil and water marks soaking into the surface.
Water resistance Water-resistant once the film dries: Once the sealed surface dries into a cured film, it offers a degree of water resistance.
Room temperature 18–25 °C ideal: Below 10 °C curing slows sharply and the surface stays soft for days.