How does a silicone strap go from liquid polymer to finished product? Inside our atelier, step by step.
Compression vs injection: why we picked one
Two molding methods dominate silicone manufacturing. Compression molding (older, cheaper) presses pre-measured material into open molds. Injection molding (modern, precise) shoots liquid silicone into closed molds at high pressure. The difference: compression yields ±0.5mm tolerance, injection yields ±0.05mm. For a cage strap that needs ±0.2mm to clip onto a watch case, injection is the only viable option.
The mold is the product
Before any silicone is poured, the steel mold itself must exist. Our Drop 01 tooling took 6 weeks to CNC-machine and cost about €35,000. A serious mold runs hundreds of thousands of cycles — the upfront commitment behind any small-batch silicone product. If we got the geometry wrong, we would have eaten the cost. We got it right on the third revision.
Two-component LSR, mixed live
Liquid Silicone Rubber (LSR) is a two-part system: Part A (silicone base) and Part B (platinum catalyst). They are pumped from separate barrels, mixed at the nozzle, and injected together. Once mixed, the curing clock starts. Pre-mixing in the barrel would set the silicone before injection — hence the live-mix step.
180°C in 30 seconds
The mold is heated to 180°C. When the liquid silicone enters, the cure (cross-linking) starts immediately. After 30-45 seconds the polymer chains are locked. The mold opens and the strap is ejected. Total cycle: under 90 seconds per unit.
Demolding without stress marks
The trick is the mold geometry. Sharp corners and tight angles create stress marks when the part is removed. Our mold uses 0.4mm radii at every transition to ensure clean demolding. You can run your finger along a POPSTRAP edge and not feel a single mold line.
In-line QC: 100% inspection
Every single unit — not a sample, every one — is visually inspected under magnification by a trained operator. The 6 checkpoints: cage fit, color uniformity, edge clean, no flash, no voids, no surface defects. Pass rate is around 96-97%; the rejected 3% goes to recycle.
Waste streams and scrap recovery
The flash (excess silicone at the parting line) is hand-trimmed and collected. Roughly 2% of input silicone goes to scrap. We send it back to our supplier monthly for re-processing — silicone is chemically recyclable, unlike most rubbers.
Why this process costs triple
A POPSTRAP at €40 manufacturing cost = €15 silicone + €10 labor + €8 mold amortization + €4 QC + €3 packaging. A Chinese factory making the same strap in compression molding would spend €4 total. We picked precision over price.