What is silicone casting and mold making?
Silicone casting (silicone mold making) pours a two-part reactive silicone over a master pattern so it cures into a flexible mold. That mold is then used to cast polyurethane, resin, wax, or other materials. The two parts — usually a base and a catalyst — must be combined at the correct ratio and mixed evenly, or the silicone cures soft, sticky, or unevenly.
- Flexible two-part molds for casting PU and resin parts
- Pattern duplication for prototyping and short runs
- Art, jewelry, props, and architectural model molds
Platinum vs. tin cure — and why it matters
Two-part mold silicones come in two main chemistries, and the difference drives most real-world failures:
- Tin-cure (condensation): more tolerant of contamination, lower cost, but shrinks slightly over time and has a shorter library life.
- Platinum-cure (addition): low shrinkage and excellent detail, but highly sensitive to cure inhibition — contact with sulfur clays, latex, tin-cure residue, some 3D-print resins, and certain adhesives can leave the surface tacky or uncured.
Knowing which you're running changes how you prep the master, clean tooling, and sequence work.
Silicone gotchas to plan for
- Cure inhibition / contamination: with platinum silicone, test a small batch on a new master before committing a full mold.
- Mix ratio sensitivity: many silicones are 1:1 or 10:1 by weight — off-ratio batches cure soft or never fully set.
- Pot life: once mixed, you have a limited working window before the silicone thickens.
- Trapped air: hand-stirring folds in bubbles that telegraph into the mold surface; high-detail molds often want a vacuum step.
How Flovv helps (and the honest scope)
Flovv is purpose-built for two-component (A:B) reactive systems: it meters both parts at a precise, repeatable ratio and mixes them in-line through a static nozzle, which reduces trapped air compared with hand mixing. Process notes: confirm your silicone's mix ratio and viscosity, work within its pot life, and pour slowly from a low height for the cleanest mold surface.
Honest scope — please read: silicone is an expanding capability for Flovv, not a blanket guarantee. Silicone systems vary widely in ratio, viscosity, and cure chemistry, and we do not claim full out-of-the-box support for every silicone. Contact us about your specific silicone system before a production run so we can confirm fit. Flovv is a low-pressure two-part liquid system — not a 3D printer and not thermoplastic injection molding.
Where hand mixing is still fine
For a single mold, an occasional one-off, or a quick test of a new silicone, weighing and hand-mixing (with a vacuum degas if detail matters) is a perfectly sensible workflow — the silicone's own ratio and pot life matter more than automation at that scale. Consistent metering pays off once you're pouring the same silicone repeatedly and want mold-to-mold uniformity.
Honest limitations
- Silicone support is expanding — confirm your exact system with us first; we'd rather set expectations than over-promise.
- Very high-viscosity silicones are harder to meter and mix cleanly at low pressure.
- Platinum systems can be inhibited by contamination outside the machine's control — clean tooling and master prep still matter.
- High-detail or bubble-critical molds may still need a vacuum degassing step.
Tell us about your silicone, then see the Flovv injection system. Once your mold is made, explore related casting routes: polyurethane casting, resin casting, and prototyping, or browse mold release and chemicals.