Dry Bag FAQ
Short answers to the questions we are asked most often about dry bag sizing, materials, water ratings, buoyancy, care and ordering. Each answer links to a longer guide with the full data, test method and specification tables. Ratings follow the ingress code standard published by the IEC, fabric figures follow ISO and ASTM methods, and safety limits follow US Coast Guard guidance on the water.
What a dry bag is
What is a dry bag and how does it work?
A dry bag is a waterproof sack made from a film-laminated fabric with welded seams. You put your kit inside, fold the coated top edge over itself three or more times and clip the buckle; the folds press the two film surfaces together and that compression is what keeps water out. Unlike a liner or a spray deck, a dry bag is a sealed container in its own right, rated to a standard such as IPX6 for heavy spray or IPX7 for thirty minutes submerged at one metre. Read the full guide.
Choosing for kayaking
What are the best dry bags for kayaking?
For day paddling, a 10L roll-top bag holds a shell layer, water and a phone and still leaves room for three folds; most paddlers pair it with a 20L for overnight kit. Look for welded seams rather than stitched and taped, a film thickness of at least 0.3 mm, and D-rings so the bag can be clipped into the hull. Choose a high-visibility colour and a bag that floats, because anything that goes overboard unclipped is gone. Read the full guide.
Sizing and capacity
Which dry bag size should I buy?
Match the size to what must stay dry plus about 20% spare volume for trapped air. Around 10L covers a shell layer, water and a camera for a half-day on the water; 20L covers a sleeping bag and clothing change for an overnight trip; 30L and up suits two people or multi-day loads. Read the full guide.
Why does my 20L bag feel smaller than another brand's 20L?
Volume is measured three ways: flat-packed, filled with water, or filled with beads. A roll-top bag has no fixed top edge, so the honest figure is litres at three folds, not litres rolled flat. Tolerance between methods runs 10 to 15 percent on identical bags. Read the full guide.
Can I use one big bag instead of several small ones?
You can, but you lose the compartmentalisation that keeps wet kit away from dry kit and you lose redundancy: one puncture in a single big bag wets everything. Three mid-size bags pack better in a hull and let you keep food, electronics and clothing separate. Read the full guide.
How much does a packed dry bag weigh?
An empty 10L roll-top bag weighs roughly 320 to 420 grams in TPU construction. Add about one kilogram per litre of dense load; clothing and sleeping bags are lighter than water bottles and camera bodies, so volume and weight do not scale together. Read the full guide.
Material and seams
What does RF welded mean and why does it matter?
Radio-frequency welding melts two thermoplastic surfaces into each other under pressure, producing a seam with no needle holes. A sewn seam punches thousands of holes through the waterproof layer and then relies on tape to cover them, and tape is what fails first after UV exposure. Read the full guide.
Is 500D always better than 420D?
No. Denier measures yarn thickness, so 500D resists abrasion better at equal construction, but it is heavier and stiffer. A well-laminated 420D with a good film outperforms a poorly bonded 500D in field use. Choose by abrasion zone rather than by number. Read the full guide.
What is hydrostatic head and what figure should I ask for?
Hydrostatic head measures how tall a column of water a fabric supports before three drops penetrate. Leisure dry bags start around 3,000 mm, technical models run 8,000 to 15,000 mm. Above roughly 15,000 mm the limiting factor becomes the seam and closure, not the fabric. Read the full guide.
Does ripstop fabric help in a dry bag?
Ripstop grids stop a small tear from running, which matters in ultralight construction where the face fabric is thin. In a laminated dry bag the film already resists tearing, so the benefit shifts to puncture containment from sharp gear rather than to overall strength. Read the full guide.
Water ratings
Is IPX7 safe for diving?
No. IPX7 means thirty minutes at one metre in laboratory still water. Diving imposes moving pressure, depth change and prolonged exposure that the rating does not cover. Use a purpose-built case for anything going below the surface. Read the full guide.
What is the difference between IPX6 and IPX7?
IPX6 is a high-pressure jet test from every direction; it tells you the bag survives heavy spray and breaking waves. IPX7 is thirty minutes submerged at one metre; it tells you the bag survives being dropped overboard and retrieved. A bag can pass either without passing the other. Read the full guide.
How many times should I roll the top?
Three folds is the practical standard, four folds when the bag goes in rough water or will be strapped to a deck where it cannot be checked. Below three folds there is not enough compression across the width of the seal to resist moving water. Read the full guide.
Why does my dry bag leak at the seam and not the closure?
Because most seam failures are actually stress failures at the corner where the body meets the base or strap. Look for whitening or creasing along the weld line, which means the film has been flexed past its fatigue limit, often by rolling the bag tightly for storage. Read the full guide.
Floating and safety
Does a dry bag float with air inside?
Yes, provided enough air stays trapped in the rolled collar and the contents are not denser than the displaced water. A bag packed solid with camera bodies and tools may still sink even when sealed, because buoyancy depends on weight as well as air. Read the full guide.
Can I use a floating dry bag instead of a life jacket?
Never. A floating dry bag is a gear-recovery device, not personal flotation equipment. It is not certified to support a person, it can deflate if the closure opens, and it offers no freeboard in moving water. Always wear a certified personal flotation device. Read the full guide.
How much weight will a 10L floating bag support?
A well-rolled 10L bag typically gives six to eight kilograms of positive buoyancy once the collar is folded four times. That figure drops as soon as the bag is squeezed, partially filled, or rolled with fewer folds than the specification assumes. Read the full guide.
Care and repair
How do I clean a dry bag after salt water?
Rinse inside and out with fresh water, paying attention to the rolled collar where salt crystals sit. Wipe with mild soap and a soft cloth, rinse again, then dry open and unrolled in shade. Machine washing damages the film and wets the interior permanently. Read the full guide.
How do I get mildew out?
Mix one part white vinegar with four parts water, wipe the stained area, leave it for an hour out of sunlight, then rinse and dry completely open. Avoid bleach, which attacks TPU. Prevention is better: never store a bag rolled while damp. Read the full guide.
Is there a safe way to remove odour?
Air drying in shade for two days removes most odour. For stubborn cases wipe with a bicarbonate and water paste, leave overnight, then rinse. Do not use solvent cleaners or heat guns; both attack the film and can delaminate the laminate. Read the full guide.
How should I store dry bags between seasons?
Clean, fully dry, unrolled or loosely folded, in a cool dark place. Rolling tightly for months creases the film along the same line every time and those creases become leak paths. Keep them away from solvents, fuel and insecticide sprays. Read the full guide.
Buying and production
What is the minimum order for a made-to-order run?
Standard minimum is 500 pieces per style, size and colourway. That figure covers machine setup, weld tooling and colour matching. Lower quantities are possible where the fabric, colour and tooling already exist in the line. Read the full guide.
How long do samples and production take?
Sampling takes six to ten working days from artwork approval. Bulk production runs 35 to 50 days after sample sign-off, longer for mill-ordered colourways. Plan another 15 to 20 days if you need a new base fabric dyed to match. Read the full guide.
What inspection standard applies?
Goods are inspected to AQL 2.5 as standard, which sets the acceptable number of minor and major defects per batch. Tighter levels are available at extra cost for premium lines. Random panels are also hydrostatic tested during production. Read the full guide.
Which documents come with the shipment?
A packing list, a commercial invoice, an inspection report at the agreed AQL level, and on request REACH and RoHS declarations, PFAS-free finish statements and GRS transaction records for recycled content. Read the full guide.
Still weighing up a specification? Write to service@junyuanbags.com with your size, volume and target market.