The zipper is the weakest point of any waterproof product. A dry bag with a perfectly welded body will still leak through a poor closure, and a tent door that sticks in wet weather is worse than no door at all. Choosing the right waterproof zipper for dry bags, tents and protective covers is therefore one of the most important decisions in the design.
This guide explains what to look for, how sealing grades differ, and how to specify a zipper that does the job.
Why the Zipper Matters Most
Fabric can be welded into a fully sealed shell, but every product needs an opening — and that opening needs a closure that seals, opens smoothly, and survives repeated use. Water finds the smallest gap, and dust and grit work their way into any loose coil. A good waterproof zipper combines a sealing tape, a well-matched coil and teeth, and hardware that stays reliable after repeated use.
Waterproof Zippers for Dry Bags
Dry bags live in the wettest conditions: splashed on a boat deck, dunked at a riverbank, or rained on for hours. The zipper on a dry bag needs to resist water from the outside while staying easy to open with wet or cold hands.
Look for a TPU-laminated tape — the TPU film seals the woven tape against water ingress — and an exposed coil that runs smoothly even when grit or sand is present. A single slider with a generous puller helps when the bag is opened one-handed. For dry bags that may be briefly submerged, consider stepping up from a water-resistant grade to a watertight grade; for bags designed to hold air or stay sealed under pressure, the airtight grade is the right choice.
Length matters here too: dry bag closures are usually short, but wide-mouth designs sometimes need longer runs. Custom lengths from 10 cm to 5000 cm mean the zipper can be cut to the bag's exact opening.
Waterproof Zippers for Tents and Canopies
Tent doors and canopy openings are long, used daily, and exposed to sun as well as rain. The priorities shift: smooth operation over a long length, UV resistance, and a tape that stays flexible in temperature changes.
An anti-UV TPU formulation is worth specifying for tents and canopies that stay pitched outdoors for weeks or months — standard TPU can degrade under prolonged sun exposure. Long custom lengths (3 m and above) are available for large tent doors and canopy panels, and a non-locking slider with a flat puller keeps the door easy to operate from inside or outside.
Waterproof Zippers for Protective Covers
Protective covers — for equipment, gear and outdoor products — are often the longest and most demanding application. Covers are fitted and removed, folded and stored, and expected to last for years outdoors. The zipper must be strong enough for a large opening, flexible enough to fold with the cover, and sealed enough to keep dust and rain out of the contents.
Our 8# TPU waterproof zipper is a common choice here: a heavy-duty #8 nylon coil, a total closed tape width of 36, 38 or 40 mm that gives a solid attachment area, and a fully separable open end with a metal pin and square box so the cover can come completely off. Custom lengths are cut to the cover's exact opening, so there is no excess zipper bunching at the ends.
Choosing the Right Sealing Grade
Not all "waterproof" zippers seal to the same level. We produce three grades:
- Water-resistant: TPU-laminated tape for rain, splashes and dust. The right choice for most covers, bags and tents.
- Watertight: A higher-grade seal for products exposed to standing water and heavy spray.
- Airtight: Our high-strength sealing grade for extreme environments. It withstands approximately 30 kPa. Only the airtight grade carries an IPX7 rating.
Choosing the grade honestly saves money: a water-resistant zipper is lighter and less expensive than an airtight one, and over-specifying wastes budget. Under-specifying, on the other hand, guarantees leaks. Match the grade to the worst conditions the product will actually face.
What to Look for in a Waterproof Zipper
- Teeth: Nylon coil teeth, exposed, for smooth and flexible operation. The #8 size suits heavy covers and large bags.
- Tape: Polyester tape with TPU lamination on the slider side. Standard film 0.2 mm, 70A softness.
- Slider: A single, non-locking slider with a black flat puller is standard; metal or plastic sliders and round or T-shaped pullers are available.
- End type: Open end with metal pin and square box for covers and bags that separate fully.
- Width: 36, 38 or 40 mm total closed width for the 8# size; other widths can be customized.
- Weight: Approximately 90 g per 100 cm length — light enough for bags, strong enough for covers.
Installation: Weld, Don't Sew
This point cannot be overstated: TPU tape must be attached by hot welding (RF technology), never by sewing. A needle hole through the TPU film is a permanent leak path, and a sewn waterproof zipper will fail its first splash test. If your factory is set up for sewing only, budget for a welding step or choose a different tape construction.
Custom Sizing and Ordering
Standard lengths of 1 m, 2 m and 2.5 m cover most products, but custom lengths from 10 cm to 5000 cm are available, along with custom colors (black is standard) and slider options. Samples are normally ready in 3 days, so you can test the zipper on your actual product before committing. Bulk production takes 7–10 days after sample approval and payment, and small-batch custom orders are accepted.
Related product: 8# TPU Waterproof Zipper – Open End