Mold Technology

Core of the digital workflow. CAD to production mold in 48 hours. CNC masters are indefinitely reusable—the master makes other molds.

· Precision ±0.05mm; surface Ra 0.8–3.2 µm

· Complex panel master: 2–8 hours milling

· 3-axis: flat panels and relief ornament (majority of work)

· 5-axis: full 3D forms (€80–500K+; outsource initially)

The long-term production answer. Sintered PMMA beads create interconnected porosity—water is forced through at 10–40 bar. Industry standard for sanitaryware since the 1990s.

· PMMA beads (100–200 µm) sintered to 25–35% porosity, 10–50 µm pores

· Water drainage is pressure-driven (active), not capillary (passive)

· No mold drying needed between casts

· For ornamental facade panels (relatively flat with relief): ideal geometry

· Multi-part PMMA molds possible for 3D ornament

The baseline. Gypsum absorbs water through natural 40–50% interconnected porosity. Cheap and proven, but short-lived and slow between casts.

· Natural capillary action drives water removal from slip

· Can handle modest pressure (0.5–3 bar) with mother mold support

· Surface degrades—absorption rate changes with age

· Must dry 4–24h between uses—limits throughput

· Good for prototyping and short runs (<50 pieces)

Flexible, handles undercuts, easy to make from masters. Non-porous—works with gelcasting, starch, and wax processes. Too expensive per-piece for true scale.

· Always platinum-cure (tin-cure degrades over time)

· Higher tear-strength: Mold Star 30T or Dragon Skin 30

· Mother molds: rigid plaster/fiberglass shell prevents deformation

· Rotate 3–4 sets per design for elasticity recovery

· 1m² panel mold: 15–30kg silicone = €450–1,800 in material

Novel concept: a material that is both flexible (demold undercuts) and porous (absorb water). Could eliminate multi-part molds for complex geometries. No literature found—potentially patentable.

· Salt-leached silicone: 30–60 wt% NaCl in PDMS, dissolve out for interconnected pores

· Core challenge: silicone is hydrophobic (contact angle ~107°)

· PAA UV-grafting solution: drops contact angle to ~9°, stable 18+ months

· Pore size problem: salt leaching gives 50–600 µm; capillary casting needs ~1 µm

· Pressure-assist (1–3 bar) can compensate for low capillary pressure

· Joule heating chemistry (Xu et al. 2024): achieves ~5 µm pores in silicone

· SLS-TPU molds (Anil & Nadimpalli, 2025): only published flexible slip-casting mold paper