Silicone & Elastomers

Silicone and thermoplastic elastomers occupy a unique space in consumer products: they are neither rigid plastics nor metals. They bend, stretch, seal, and cushion. They are found in kitchen utensils, baby bottles, medical wearables, watch bands, gaskets, and waterproof seals. Their defining characteristic is that they return to their original shape after deformation — and they do it thousands or millions of times.

For hardware founders, elastomer selection matters because the material directly affects user safety, product durability, and regulatory compliance. A silicone spatula that leaches fillers into food, a watch band that irritates skin, or a gasket that takes a compression set and no longer seals — these are failures that trace back to the wrong material choice.

Silicone rubber (solid silicone) is the premium elastomer for consumer products. It is naturally inert, hypoallergenic, odorless, and stable from -40 deg C to 230 deg C. It does not degrade under UV or ozone. Food-grade and medical-grade silicones are available with certifications (FDA, LFGB, USP Class VI). Solid silicone is typically compression-molded, which is slower and more labor-intensive than injection molding — making per-part cost higher.

Liquid Silicone Rubber (LSR) is injected into a mold like plastic — fast, automated, and precise. LSR parts have excellent detail reproduction and are used for high-volume items like baby bottle nipples and medical seals. The mold cost is higher than compression molding but cycle times are dramatically faster. LSR is the right choice when volume exceeds ~10,000 units.

TPE (thermoplastic elastomer) and TPU (thermoplastic polyurethane) are processed on standard injection molding machines — no special equipment needed. TPE is the cheaper, softer option, commonly used for toothbrush grips and soft-touch overmolds. TPU is tougher and more abrasion-resistant, used for phone cases and watch bands. Both can be overmolded onto rigid plastics in a single tool. The trade-off: neither matches silicone for heat resistance, chemical inertness, or long-term compression set resistance.

Natural and synthetic rubbers (EPDM, nitrile, neoprene) are used for industrial gaskets, hoses, and seals. They are rarely the right choice for consumer products because they off-gas odors, can cause allergic reactions, and lack the clean aesthetic of silicone. EPDM is the exception for outdoor weather seals — it outperforms silicone on UV and ozone resistance at a lower cost.