Dry Bag Manufacturer: OEM Roll-Top Production in China

Dry Bag Construction Deep Dive

A welded dry bag has only four structural components: the film panel, the bottom seam, the side seams and the roll-top closure. Everything else — straps, D-rings, windows, exterior pockets — is an accessory that either reinforces the bag or adds failure points. The film panel is die-cut to a one-piece tube, then the bottom is hot-air welded in a straight line. The two side seams are welded next, forming the bag body. The top edge is folded over and welded to create a channel for the roll-top closure clip. When a factory tells you they "sew then tape" a dry bag, walk away: every needle hole is a potential leak path, and tape adhesive degrades over 12–24 months of UV exposure. True dry bags must be welded.

Testing Beyond the Submersion Tank

Submersion testing is the baseline. Serious outdoor brands also require: hydrostatic pressure testing to JIS L 1092 at 10,000 mm minimum (we test to 15,000 mm on our premium TPU line); cold-crack testing at -20°C to ensure the film does not become brittle in winter; UV exposure testing over 200 hours to ISO 4892; abrasion testing with a Martindale taber; and seam peel testing to ASTM D751 at 25 N/5cm minimum. We run all of these in-house and can share test reports for your material spec. If your target market is California, also ask for Prop 65 compliance documentation on the PVC plasticizer and hardware.

Design Options That Increase Unit Cost

Not every design upgrade is worth its cost. The highest-impact upgrades buyers ask for are: a transparent window on the front (adds a film lamination step, +8–12% cost), exterior zippered pockets (each aqua-zipper adds USD 4–8), padded shoulder straps on a dry backpack (adds sewing labor), a MOLLE webbing system (adds cutting and sewing), and a removable interior dry liner (adds a second welded bag inside). The lowest-impact upgrades are unnecessary: extra D-rings that the customer will never clip to, contrast-color webbing that increases SKU complexity, and embossed PU patches that fail UV testing. Our merchandisers will tell you on the quote which upgrades are worth it and which are decorative.

Sizing and Capacity Naming

"20L" is a marketing number, not a measured volume. The industry convention is to fill the bag to its rolled neck and measure the displaced volume, but different factories measure differently. When you specify a size, provide the actual dimension (e.g., 50 cm tall × 35 cm circumference, rolled three times) rather than trusting the liter label. We provide a dimensioned drawing on every tech pack so the buyer and the factory agree on the real size before cutting. If you are replacing an existing bag on the market, send us the physical sample and we will match the dimensions within ±5 mm.

Roll-Top Engineering: How Many Folds?

The roll-top closure works by creating a long, labyrinthine water path through folded fabric. The industry standard is three to five folds before clipping. Fewer than three folds and the bag is spray-resistant but not submersible; more than five folds and the bag loses usable volume and becomes awkward to pack. We engineer the neck length so that three folds leave the clip at a comfortable height on a 20L bag. For phone pouches, the closure is a simple rubber snap rather than a roll-top because the small opening cannot accommodate three folds. When you spec a dry bag, tell us the target submersion rating (IPX6 spray vs IPX7 1m/30min vs IPX8 continuous), and we will specify the neck length and fold count accordingly.

Transparent Windows and Touchscreen Compatibility

Transparent phone dry pouches are a high-volume SKU for beach and promo buyers. The window film is a clear 0.3mm TPU laminate that remains touch-sensitive underwater up to about 1 meter. We size windows for phones up to 6.9 inches (iPhone Pro Max class). For tablets, we build larger transparent pouches on the same construction. Note that underwater touch sensitivity drops because water conducts the touch signal away from the finger; for underwater photography, plan to use the volume-button shutter or a physical Bluetooth remote. We can provide a sample so you can test the exact touch behavior on your phone model.

Color, Pantone and MOQ Complexity

Every custom color adds a small setup cost and increases the MOQ per color. Our stock TPU film comes in black, orange, yellow, blue, green and grey; these colors are available at the standard MOQ of 500 pcs per size. Custom Pantone colors require a film dye lot, which adds USD 150–300 setup and raises the per-color MOQ to 1,000 pcs. Most buyers start with a stock color for the first order and move to custom colors on reorders once the SKU proves out. We also offer two-tone bags (black body, orange trim) at no extra setup if both colors are stock colors.

Packaging and Retail-Ready Options

Standard packaging is a single polybag per bag, 50 pcs per export carton. For retail buyers, we offer: hang-hole header cards (polybag with hang tab), printed retail boxes (CMYK 4-color), instruction cards in English, Spanish, French or German, and barcode / FNSKU labeling for Amazon. Retail packaging adds USD 0.40–1.20 per unit depending on complexity. We can also produce reusable mesh stuff sacks as a premium alternative to polybags, popular with outdoor brands targeting eco-conscious customers.

People Also Ask: Dry Bags

Are your dry bags IPX7 or IPX8 rated?

Our welded TPU dry bags pass a 30-minute submersion at 1 meter, equivalent to IPX7. For IPX8 (continuous submersion), we build heavier 0.7mm TPU bags with dual-welded seams. We label products accurately: a bag that passes IPX7 is not marketed as IPX8 unless it passes the deeper test.

Can dry bags be used in saltwater?

Yes. We recommend rinsing the bag in fresh water after saltwater use to prevent salt crystallizing on the zippers and seams. Our marine-grade TPU construction is saltwater-resistant; generic PVC bags can become brittle after repeated salt exposure.

What is the largest dry bag you can manufacture?

We regularly build 50L dry duffels and expedition dry bags. Larger sizes (70L+) are possible but require a custom cutting die and the 500 pcs MOQ. Let us know your target dimensions and we will confirm feasibility.

Can you make floating dry bags?

Floating requires foam or air-cell insulation built into the bag walls. We build floating cooler dry bags and boat bags with PE foam insulation. These are a separate product family; see our cooler bags page.

How do I clean a dry bag?

Wipe with mild soap and fresh water, air dry fully before storage. Do not machine wash or dry clean. Store loosely rolled (not tightly compressed) in a cool, dry place away from direct sunlight. We include a printed care card in retail packaging.

Do you make kids' dry bags?

Yes. For kids' products sold in the US, we follow CPSIA and CPC requirements, including tracking labels and phthalate testing. We have built kids' beach dry bags and mini backpacks for EU and US brands.

How to Care for a Dry Bag in the Field

Even a fully welded dry bag will fail if abused. Rinse with fresh water after saltwater or sand exposure. Dry fully before packing away; trapped moisture grows mildew on the interior lining. Avoid contact with sharp rocks, boat gunnels and hot exhaust pipes. Do not overstuff beyond the rated capacity — overstressing the roll-top clip can warp the seam. Store loosely rolled rather than tightly compressed. With normal care, a welded TPU dry bag should last 3–5 years of regular outdoor use. We include a printed care card in every retail pack so your end customers know how to treat the product.

Warranty and After-Sales Support for Buyers

We stand behind production defects for 12 months from shipment. If a customer returns a bag with a welded-seam failure (not caused by misuse), we credit or remake. We do not require the buyer to ship the failed bag back to China; photos and a short video are enough to verify. For Amazon sellers, this means you can issue replacements to your customers without absorbing the full cost. We also provide replacement parts — buckles, clips, shoulder straps — for buyers who want to offer repair service under their own warranty.