Airtight zippers are not a commodity. Two suppliers can both quote “IPX8 waterproof zipper” and still be producing closures that behave completely differently under pressure. The difference is what they are willing to publish and test.
What to compare
| Criterion | What to ask for |
|---|---|
| Published test values | A seal-strength figure (e.g. 60 kPa), a cycle figure (e.g. 3,000+), and the test conditions behind them |
| Rating coverage | Whether the supplier tests IPX6, IPX7 and IPX8, and under what nozzle, depth and duration |
| Material range | TPU, PEVA, silicone rubber and nylon woven capability rather than a single material |
| Process range | HF welding, sewing with tape, and bonding — because the process must match your host material |
| Customisation envelope | Length range, tape width, colour, slider and opening style |
| Documentation | Test reports for the rating you need, and certification documents on request |
Red flags
- A rating quoted without test conditions — IPX8 is defined “by agreement”, so the depth and duration must be stated.
- No published seal-strength figure for an airtight product; water rating alone does not describe pressure performance.
- A single material offered for every application.
- Unwillingness to sample against your own material — the finished assembly is what has to pass, not the zipper alone.
