Not all silicone is the same. Two production methods — platinum curing and peroxide curing — yield materials that look identical on a shelf but behave completely differently on your wrist over time. If you're buying a silicone watch strap, knowing the difference is the fastest shortcut to not wasting money.
Two Ways to Cure Silicone
Silicone rubber starts as a polymer that must be cross-linked — cured — before it becomes the firm, flexible material you can actually wear. Two catalysts do this job:
- Peroxide curing uses organic peroxides as the cross-linking agent. It's the older method, widely used because the raw materials are cheaper and the process runs fast.
- Platinum curing (also called addition curing) uses a platinum complex as the catalyst. It's more demanding to run, and significantly cleaner at the molecular level.
The end product looks the same. The chemistry is not.
Why Peroxide Curing Falls Short
Peroxide curing leaves residue. When the peroxide catalyst triggers cross-linking, it decomposes into by-products — volatile organic compounds — that stay trapped in the material after molding. Over time, those compounds migrate to the surface.
The result: a faint odor that never fully disappears, a slightly tacky surface texture, and a material that can discolor under UV or heat exposure. Some manufacturers attempt a secondary post-cure step (an oven cycle to drive out residues), but this adds cost and time, and it doesn't eliminate the problem — it reduces it.
For watch straps worn directly against skin, this matters. You're putting the material in contact with your wrist for eight to sixteen hours a day.
Why Platinum Curing Changes the Equation
Platinum-cured silicone produces no organic by-products during the reaction. The platinum catalyst is fully incorporated into the cross-linked network and doesn't migrate. What you get is a chemically inert material.
The downstream effects are measurable:
| Property | Peroxide-Cured | Platinum-Cured |
|---|---|---|
| Residual by-products | Present | None |
| Odor tendency | Possible | Negligible |
| Surface stability | Moderate | High |
| UV resistance | Lower | Higher |
| ISO 10993 biocompatibility | Sometimes | Standard |
| Post-cure step required | Often | No |
Platinum-cured silicone is the default material for medical devices, food-contact applications, and infant products. When a strap brand claims "medical-grade silicone," what that claim requires is platinum-cured silicone tested to ISO 10993 standards. If they don't specify the curing method, the question is worth asking.
What This Means on Your Wrist
The practical difference shows up in three ways.
Longevity. Platinum-cured silicone maintains its mechanical properties — tear resistance, elongation, Shore hardness — longer than peroxide-cured equivalents under the same UV, heat, and sweat exposure. The material doesn't degrade at the same rate because there's nothing to volatilize out of it.
Skin behavior. A cleaner cure means a more inert surface. Platinum-cured silicone is less reactive to skin oils, sweat, and topical products. It's also what makes the material compatible with ISO 10993, the international standard for materials in prolonged skin contact. Learn more in our silicone strap guide.
Smell. Platinum-cured silicone doesn't develop the characteristic rubbery smell that peroxide-cured straps sometimes carry, especially when new or after heavy sweating. Some buyers chalk that odor up to silicone in general. It isn't. It's a curing method problem.
The POPSTRAP Material Standard
POPSTRAP uses Shore A 50 platinum-cured silicone, specified at the medical-grade threshold and tested for ISO 10993 biocompatibility. We chose it because it's the correct material for prolonged skin contact — not because it's the easiest or cheapest option to source and process.
Our formulation runs without plasticizers or fillers that compromise long-term performance. The full production process — from raw polymer to finished strap — happens in our workshop in the Loiret region, 90 minutes south of Paris. One location. One product. No shortcuts.
The strap you wear every day should be held to the same standard as the watch it carries.
One strap. Built right.
POPSTRAP Drop 01 is available now at €130, free worldwide shipping. View the POPSTRAP cage strap →
POPSTRAP is not affiliated with, endorsed by, or connected to Audemars Piguet® or Swatch Group®.