These are three levels of sealing: airtight zippers block both air and liquid and handle pressure differentials — the highest grade; watertight zippers block liquid water and handle short immersion but not sustained pressure; waterproof zippers resist splashes and brief rain. The simple test: does your product need to hold pressure?
Airtight vs watertight vs waterproof
| Type | Definition | Rating | Structure | Typical uses |
|---|---|---|---|---|
| Airtight | Blocks air & liquid, holds pressure | IPX8 + pressure test | One-piece TPU, sealing lip, minimal seams | Drysuits, military, medical isolation, high-pressure inflatables |
| Watertight | Blocks liquid water, short immersion | IPX7 | Nylon/TPU composite, tape seal | Wading suits, snorkelling, outdoor dry bags |
| Waterproof | Splash and rain resistance | IPX6 | Coating or standard tape | Rainwear, general outdoor, everyday items |
Key differences
- Pressure: airtight holds pressure differentials; watertight and waterproof do not.
- Immersion: IPX7 lasts ~30 min; IPX8 allows continuous immersion.
- Structure: airtight zippers use one-piece TPU with fewer seams and lower failure risk.
- Material & flexibility: higher grades mean thicker material — balance flexibility against strength.
