Dry Bag Manufacturer in China

Sealock is a dry bag manufacturer in China supplying OEM, ODM, and wholesale buyers worldwide. The dry bag is the oldest and simplest product in waterproof gear — a single welded chamber closed by rolling the top — and it remains the benchmark by which a waterproof factory is judged. There is nowhere to hide: no lining to disguise a bad seam, no zipper to blame. Either the welds hold and the closure seals, or the customer's sleeping bag comes out wet. This overview covers how a dry bag is built properly, what actually causes the failures buyers hear about, and the sourcing terms.

The Uncomfortable Truth About Dry Bag "Leaks"

Any brand selling dry bags will field complaints that a bag leaked. The evidence from testing is consistent and worth understanding before you spec a product: most leaks are not manufacturing defects — they are closure and loading errors. In side-by-side submersion tests a properly sealed bag stays dry while an improperly sealed one from the same batch leaks immediately.

Two user behaviours cause the majority of it:

• Not enough folds. A roll-top only seals when the opening is folded over itself at least three times before clipping — the pressed layers are the seal. Rolled once or twice "to save time", a perfectly good bag leaks every time.
• Overfilling. Stuff a dry bag to capacity and there's no slack left to fold. Forcing the buckle shut on a full bag doesn't create a seal at all. The working rule is to fill to about 80% and size up rather than squeeze.

The commercial implication for a brand is direct: printing the closure instructions on the product and packaging prevents more negative reviews than any specification upgrade. A bag that says "roll down 3–4 times, then clip" on the closure strip converts a support problem into a solved one.

That said, genuine build failures do exist — and they're the ones a buyer controls at the factory: stitched-and-taped seams whose tape lifts with age, pinhole leaks in seam construction, buckles breaking under normal tension, and coatings wearing through at abrasion points.

How a Dry Bag Is Built Properly

• High-frequency welded seams — panels fused at 27.12 MHz with no needle holes. This is the dividing line in the category: stitched-and-taped bags rely on adhesive tape that ages and lifts, while a welded seam is effectively part of the fabric. It's why a welded bag survives repeated submersion and a taped one degrades.
• A roll-top with a back-up seal — a fold-seal system, with a Velcro backing strip on some builds for extra security before the buckle closes.
• Material matched to the hazard — 500D PVC tarpaulin for abrasion and rock contact; TPU-coated fabric where light weight and cold flexibility matter. For kayaking and rafting, where contact with rock is likely, the heavier PVC is the safer specification.
• Buoyancy — rolled and buckled with air inside, the bag floats, so gear dropped overboard stays findable at the surface.
• Carry that scales with size — small sizes take a single adjustable cross-body strap; larger sizes need backpack-style double straps, and the biggest benefit from a chest strap for stability.
• Proof on the finished bag — a real water-submersion test, rather than a fabric figure. The construction distinction is set out in our guide to waterproof vs water-resistant laptop bag construction.

The Failure Points Worth Speccing Against

The Factory: Capacity and Certifications

• Dongguan: 12,000 m², 400+ staff, nine HF welding lines, output around 100,000 units per month; over twenty years in welded waterproof bags.
• Two Ho Chi Minh City, Vietnam plants for diversified origin and US-tariff mitigation.
• Exports to 40-plus countries; 20-plus waterproofing patents; OEM production for brands including SIMMS, PENN, West Marine, attwood and CHUMS.
• Certifications: SMETA P4, HIGG, SCAN, GRS, BSCI, ISO9001, with an IP-protection process for private-label programmes.

Dry Bag Range

These welded bags, from Sealock's dry bag line, cover the main formats and serve as equal starting points for an OEM order — none is ranked above another; pick whichever suits the use case and customize from there.

Roll-Top Tube Dry Bags

The classic single-chamber sack, offered across the full capacity ladder from a 2L pouch to a 100L expedition sack:

Image	Model & specs	Fits	Construction	MOQ
	SL-D002 Tarpaulin Tube Dry Bag — 5/10/20/30L; 500D PVC tarpaulin; yellow, blue, black, red, grey, pink, white, orange; adjustable shoulder strap + D-ring; floats; sample 7 days.	The core roll-top range	HF-welded; 500D PVC	500
	SL-D002 15L Wet/Dry Bag — 15L, dia. 20×48 cm; 500D PVC tarpaulin; one adjustable shoulder strap; recycled option; silk-screen; sample 3–5 days, production 20–35 days.	Motorcycle, travel, promotional	HF-welded; 500D PVC	300–500
	SL-D002 5L Beach Tube Dry Bag — 5L; orange, black, yellow, red, blue, pink, white, army green; Bureau Veritas; sizes also 3–40L; materials PVC, 500D PVC mesh, 420D TPU, 70D/30D PVC.	Beach, day use, promotional	HF-welded; PVC	500
	SL-D135 20L Roll-Top Dry Tube Bag — 500D PVC tarpaulin; black, red, blue, yellow, green, grey, orange; fold-seal system with back-up Velcro seal; inner pocket with waterproof zipper; ISO9001, BSCI, Bureau Veritas; sample 7 days.	Kayaking, fishing, rafting — redundant sealing	HF-welded; 500D PVC	500
	SL-D135 Kayaking Tube Dry Bag — 500D PVC tarpaulin; roll-top; seven colours; zip pocket version; ISO9001, BSCI, Bureau Veritas; supply 20,000 pcs/month.	Kayaking, beach, daily outdoor	HF-welded; 500D PVC	500
	SL-D069 20L Ocean Pack — 20L, dia. 24.5×60 cm; 500D PVC tarpaulin 0.48 mm; transparent pocket for a smartphone; REACH, EN71, RoHS; sample 3–5 days.	Camping, swimming, diving, rafting	HF-welded; 500D PVC	500
	SL-D069 Dry Bag (full size ladder) — 5/10/15/20/30/40/50/60/80/100L, dimensions per size from D15.5×H45 cm to D36×H115 cm; 500D PVC mesh; eight colours; sample 7–10 days.	The widest capacity ladder — to 100L	HF-welded; 500D PVC mesh	200
	SL-D110 Dry Bag with Window — 2/5/10/15/20/30/40/60/80L; 500D PVC tarpaulin / mesh; transparent window so contents are visible; red, yellow, blue, green, black, gray, orange, pink; supply 10,000 pcs/month.	Adventure, diving, swimming, boating, rafting	HF-welded; 500D PVC	500
	SL-D693 Tube Dry Bag with Window & Zip Pocket — 15L (53×36 cm) / 20L (57×38 cm); 500D PVC tarpaulin; IPX7; transparent viewing window; dry-wet separation; floats; detachable reinforced webbing strap, POM buckle; yellow, black.	Wet/dry separation with visibility	HF-welded; 500D PVC	300
	SL-D009 Beach Tube Dry Bag — 5/10/20/30L; 500D PVC; black, blue, red, grey; SGS, EN71.	Camping, swimming, diving	HF-welded; 500D PVC	300–500
	SL-D026 Swimming Tube Dry Bag — 5/10/15/20/30/40L with published dimensions per size; 500D PVC mesh; black, grey, blue, red, pink, yellow, orange; sample 7–10 days.	Swimming, walking, hiking, kayaking	HF-welded; 500D PVC mesh	200
	SL-D054 Tube Dry Bag — 5/10/12/15/20/25L; PVC & TPU tarpaulin; black, blue, yellow, red, green, purple; supply 10,000 pcs/month.	Boating, surfing, rafting, camping, beach	HF-welded; PVC & TPU	500
	SL-D051 2L Dry Tube Bag — 2L; 500D PVC tarpaulin 0.50 mm; black, blue, yellow, red; fold-seal with back-up Velcro; REACH, EN71, Bureau Veritas; small quantities accepted.	Phone, keys, wallet — promotional add-on	HF-welded; 500D PVC	500
	SL-D045 Ultralight Tube Dry Bag — 20L, dia. 24.5×55 cm; 70D nylon-coated PVC — the lightweight option; black, yellow, red; adjustable strap + D-ring.	Weight-critical paddling, hiking	HF-welded; 70D nylon PVC	500
	SL-D045 Airtight Tube Dry Bag with Gas Valve — 20L; sizes 2L to 100L; PVC; gas valve for controlled inflation/deflation; customised colours; sample 5–7 days.	Sea play, buoyancy-critical use	HF-welded; PVC	500

Note the range of options within one format: a transparent window where contents need to be visible, a fold-seal with a back-up Velcro strip for redundancy, a gas valve where controlled inflation matters, 70D nylon-coated PVC where weight is critical, and an IPX7-rated build with dry-wet separation.

Dry Backpacks

The same welded construction with a carry system, for when the load has to be walked or paddled any distance:

Image	Model & specs	Fits	Construction	MOQ
	SL-E102 Dry Backpack — 15L (D24.5×H50 cm) / 20L (D24.5×H60 cm) / 30L (D24.5×H75 cm); 500D PVC mesh; custom colours; sample 7–10 days; production 30–35 days.	Swimming, hiking, camping, kayaking	HF-welded; 500D PVC mesh	300
	SL-D025 Kayaking Dry Backpack — 5/10/15/20/30/40L with dimensions per size; 500D PVC mesh; custom colours; sample 7–10 days; supply 50,000 pcs/month.	Kayaking, swimming, outdoor sport	HF-welded; 500D PVC mesh	300
	SL-E977 Kayak Dry Backpack — 28L; 500D PVC, 0.5 mm; semi-circular shell; front window pocket for a phone; multi-function lock for a paddle board; side inflation/deflation valve for temporary flotation; one-piece EVA back panel.	A full day of kayaking — flotation and lock	HF-welded; 500D PVC 0.5 mm	300–500
	SL-E978 Kayak Dry Backpack — 28L; 500D PVC, 0.5 mm; semi-circular shell; phone window; multi-function lock; inflation/deflation device; EVA back panel to cut weight and heat.	Paddling with flotation back-up	HF-welded; 500D PVC 0.5 mm	300–500
	SL-E090 Airtight Dry Backpack — 60L (36×25×80 cm); TPU; black, yellow, red; folds down for transport; floats.	Large-volume travel, camping, hunting, rafting	HF-welded; TPU	300–500
	SL-E801 30L Dry Backpack — 30L (29×19×70 cm); 500D PVC tarpaulin; resin mesh carry system; internal phone pocket; yellow, red, blue, black, grey, white, orange.	Cycling, camping, hiking	HF-welded; 500D PVC	300–500

The two kayak models are worth noting for specification ideas: both carry a front window pocket for a phone, a multi-function lock for securing a paddle board, an inflation and deflation valve that lets the bag be filled with air for temporary flotation support, and a one-piece EVA back panel to cut weight and heat on the walk in.

Capacity, material, colourway, closure, pockets, carry system and branding are all specifiable per order. Capacity selection and the roll-down volume loss are covered in our custom waterproof camping bag buying guide, and the closure trade-offs in our guide to roll top vs waterproof zipper camping bags for oem projects.

Applications

• Paddlesports — kayaking, canoeing, rafting and SUP, where submersion is a matter of when, not if.
• Fishing and boating — wet decks, spray, and tackle abrasion.
• Camping and hiking — sleeping bags, clothing, and electronics kept dry through rain and damp ground.
• Beach and travel — sand, saltwater, and wet swimwear.
• Promotional and private label — bright, branded sacks at volume, one of the strongest promotional formats in outdoor.

OEM / ODM and Custom Development

Quality Control and the Customer Inspection Procedure

Quality is gated in three tiers — IQC (incoming tarpaulin, buckles and webbing against the signed colour card, with colour difference and fastness), IPQC (cutting tolerance, weld integrity and strap-anchor assembly on the line, with test welds before each run), and OQC (AQL sampling, a real water-submersion batch test, and gold-sample comparison, with SGS or QIMA inspection available). Sealock also strictly executes the complete customer inspection procedure on finished goods: unboxing, vacuum extraction, a 24-hour static rest, and air-leak determination — on a single-chamber welded bag this is the most revealing test there is, because a pinhole that passes a brief dunk still bleeds vacuum over a full day. The lab additionally runs weld bond and peel strength, a 1,500+ cycle load test with jerk-loading on strap anchors and buckles, abrasion, tear, tensile, salt spray, UV, colour fastness and colour difference.

FAQ: Sourcing Dry Bags

Q: Why do customers say their dry bag leaked?
A: Usually because the top wasn't folded over enough times, or the bag was overfilled so no slack was left to roll. In controlled tests, a correctly sealed bag stays dry while an incorrectly sealed one from the same batch leaks immediately. Genuine build failures are the minority — and they come from stitched-and-taped seams, not welded ones.

Q: How full should a dry bag be?
A: About 80%. The roll-top needs slack to make three or four folds; forcing a buckle shut on a stuffed bag doesn't seal it. Advise customers to size up rather than squeeze — and print the instruction on the product.

Q: PVC or TPU for a dry bag?
A: 500D PVC tarpaulin for abrasion resistance and rock contact — the safer choice for kayaking and rafting. TPU where lighter weight and cold flexibility matter, at the cost of some puncture resistance.

Q: Will a dry bag survive full submersion?
A: A welded roll-top bag, properly closed, handles immersion — that's what it's built for. It is not diving equipment, though: prolonged deep submersion is outside the design intent, and that limit should be stated rather than glossed over.

Q: How can we test bags on arrival?
A: Seal a bag with air trapped inside and hold it underwater; escaping bubbles mark exactly where water could get in, usually a seam or the closure. It takes a minute and is worth doing on every new sample.

Q: What are the MOQ and lead times?
A: Typically 300–500 pieces per model, samples in 7–15 days, and production around 30–45 days after approval.

Talk to the Factory

For quotations, samples, and OEM/ODM proposals on dry bags, contact Sealock at info@sealock.com.hk or +86-769-82009361. Over twenty years of high-frequency welding, nine welding lines, dual China–Vietnam production, and a full customer inspection procedure on every shipment.