TPU dry bags are made from thermoplastic polyurethane film, prized for staying flexible in the cold, resisting UV and welding into strong seams. They cost more than PVC but deliver the best all-round waterproof performance.
People searching for "tpu dry bags" usually want a direct, practical answer - and this page delivers one. This guide explains the TPU dry bag materials and construction methods that determine waterproofing, weight, durability and cost, so you can choose the right film and seam for your use case.
The performance case
TPU remains supple below freezing, shrugs off sun exposure and handles repeated flexing without cracking. For cold water, clear pouches and premium gear, it is the material of choice.
Welding and clarity
TPU welds with RF or hot-air equipment into clean, transparent or colored seams. Its clarity also makes it ideal for phone pouches and bags with see-through windows.
Where to use it
Choose TPU for phone bags, cold-climate dry bags, clear waterproof pouches and premium outdoor lines where the higher cost is justified by performance.
How the material affects weight
Weight scales with the film. Coated nylon is lightest, TPU is mid-weight, and PVC is heaviest. For backpackers and travelers, saving grams matters; for a boat or car-based trip, heavier PVC durability is less of a burden.
A TPU dry bag spec sheet usually lists the film thickness in mil or mm plus the finished weight. Thinner film is lighter but less puncture-resistant, so match thickness to the abuse the bag will face.
Denier and film thickness
A TPU dry bag spec lists film thickness in mil or mm and, for coated fabrics, denier for the base weave. Higher denier means a heavier, tougher base fabric, while thicker film adds puncture resistance and weight.
Match the numbers to the abuse: a thin, light film suits packable travel bags, while a thicker film or higher denier suits river and expedition use.
Why seams matter more than fabric
A TPU dry bag leaks at the seam or closure far more often than through the film. That is why factories spend so much effort on welding quality and closure hardware, and why stitched bags must be seam-taped.
When evaluating a supplier, ask about the welding method and the seam test. A smooth RF weld with documented seam-strength testing is a strong signal that the bag will hold water out.
TPU, PVC and coated nylon compared
TPU (thermoplastic polyurethane) is a flexible, weldable film that stays soft in cold weather and resists UV better than PVC. It is the premium choice for lightweight, high-performance dry bags.
PVC (polyvinyl chloride) is tougher and cheaper but heavier, and it stiffens below freezing. Coated nylon uses woven nylon with a waterproof coating or laminate, giving the lightest and most packable fabric.
Eco-friendly and recycled options
TPU is generally seen as more eco-friendly than PVC because it is phthalate-free and easier to recycle, though no plastic is fully green. Recycled polyester or nylon fabrics with a TPU coating reduce virgin material use.
If sustainability matters to your brand, ask a TPU dry bag supplier about recycled fabric options, phthalate-free PVC and REACH compliance. These are increasingly available and can be a genuine differentiator.
Coatings vs laminates
A coated TPU dry bag has a waterproof layer applied to one side of the fabric; a laminate bonds a film to the fabric. Laminates are usually more durable and easier to weld, but both can be fully waterproof.
Ask which construction a supplier uses, because it affects weight, weldability and how the bag ages. Laminated TPU is the common premium construction.
| Property | Value |
|---|---|
| Cold flexibility | Excellent |
| UV resistance | Good |
| Seam | Welded |
| Material | Waterproofing | Weight | Durability | Cold / UV | Cost |
|---|---|---|---|---|---|
| TPU | Excellent, weldable | Light | Good | Best UV, soft in cold | Higher |
| PVC | Excellent, weldable | Heavier | Very high | Stiffens in cold, moderate UV | Lowest |
| Coated nylon | Good (depends on coating) | Lightest | Good | Moderate | Medium |
| Method | How it works | Best for |
|---|---|---|
| RF / high-frequency | Fuses film with electromagnetic energy | PVC and TPU seams |
| Heat sealing | Heated bar melts film together | Thinner films, simple seams |
| Seam taping | Waterproof tape over stitched seams | Coated nylon fabrics |
| Priority | Best material |
|---|---|
| Lightest weight | Coated nylon |
| Lowest cost | PVC |
| Cold weather | TPU |
| Puncture resistance | Thick PVC |
| UV exposure | TPU |
| Thickness | Typical use |
|---|---|
| 0.3-0.5mm | Light travel bags |
| 0.5-0.7mm | Everyday dry bags |
| 0.7mm+ | Expedition and river bags |
Why TPU is the premium default
TPU (thermoplastic polyurethane) dry bags use an aliphatic TPU film, usually 0.35 mm, 0.5 mm or 0.7 mm thick, often laminated to a polyester or nylon scrim. TPU is lighter than PVC, stays flexible below freezing, is UV-stable, and rf-welds cleanly into seams that outlast the bag body. It is the fabric on Sea to Summit, Watershed and most premium paddling bags.
A 0.5 mm TPU film runs about 280 g/m², versus 550 g/m² for a 0.5 mm PVC film of similar strength. For a 20 L bag that is a 200 to 250 gram empty-weight saving - meaningful on a backpack but invisible in a canoe.
Aromatic vs aliphatic TPU
There are two TPU chemistries. Aromatic TPU is cheaper but yellows and embrittles under UV within 6 to 12 months of sun exposure. Aliphatic TPU is UV-stable, stays clear or matte for years, and costs about 25 to 40 percent more. For a dry bag that lives on a boat deck, aliphatic is non-negotiable; for a pack liner that never sees sun, aromatic is fine.
Ask the supplier which chemistry they use and request the UV aging report. A 500-hour xenon-arc test should show at least 80 percent tensile retention for aliphatic TPU; aromatic will show 50 percent or less. our affiliated manufacturer specifies aliphatic TPU for all external marine bags and aromatic only for pack-liner SKUs where sun is not a factor.
Thickness and weight ladder
TPU gauges: 0.35 mm for ultralight 5 to 10 L pouches (about 200 g/m²), 0.5 mm for the 20 to 30 L workhorse (280 g/m²), 0.7 mm for expedition and commercial rental (390 g/m²). Each step up adds about 100 to 110 g/m² and roughly 20 percent to film cost, but roughly triples abrasion life.
Do not over-spec. A 0.7 mm TPU phone pouch is absurdly heavy; a 0.35 mm TPU rafting bag will not survive. Match gauge to capacity and abuse, and keep the die-cut pattern the same across gauges so you can offer a light and tough version of the same SKU.
TPU recycling and end-of-life
TPU is recyclable through specialist polymer streams and does not leach phthalates, which is why premium outdoor brands are switching from PVC. It is not widely curbside-recycled, but it does not carry the PVC compliance baggage. For a brand positioning as eco-premium, TPU is the defensible choice.
Aliphatic TPU: the UV question
Aromatic TPU is cheaper but yellows in 6 to 12 months of sun. Aliphatic TPU stays clear or matte for years. For any bag marketed for boat deck, SUP or roof rack, aliphatic is non-negotiable. For pack liners that never see sun, aromatic saves 25 to 40 percent. Ask the supplier which chemistry and request the 500-hour UV retention report.
A quick visual test: aromatic TPU yellows noticeably after 3 months on a windowsill. Aliphatic stays the same color. If a supplier cannot tell you which one they use, they are buying commodity film and you cannot trust the UV claim. Spec aliphatic in writing on the PO.
TPU thickness ladder
0.35 mm TPU: 5 to 10 L pouches, about 200 g/m². 0.5 mm: the 20 to 30 L workhorse, about 280 g/m². 0.7 mm: expedition and commercial, about 390 g/m². Each step adds ~100 g/m² and ~20 percent to film cost, but roughly triples abrasion life. Match gauge to capacity and abuse.
Do not over-spec. A 0.7 mm phone pouch is absurd. A 0.35 mm rafting bag will not survive. The gauge is the spec buyers feel but never see on the tag.
TPU bag FOB price ladder
0.35 mm TPU: $4 to $6 at 1,000 pieces. 0.5 mm: $6 to $9. 0.7 mm: $9 to $13. At 5,000 pieces, each tier drops 10 to 15 percent. Aliphatic UV-stabilized adds 10 to 15 percent over aromatic. GRS recycled adds 10 to 18 percent.
Spec aliphatic for external boat bags, aromatic for pack liners. Match gauge to capacity.
TPU bag storage
Store TPU bags unrolled, in a cool, shaded place. Do not leave them in a hot car trunk - heat softens the film and warps the seams. A TPU bag stored properly lasts 5 years; one baked in a trunk lasts 18 months.
Aliphatic spec
Spec aliphatic TPU for any external boat or deck bag. Aromatic yellows in 6 to 12 months. Ask for the 500-hour UV retention report. Write 'aliphatic UV-stabilized' on the PO. Without that sentence, commodity film may ship.
TPU thickness ladder
0.35 mm TPU: 5 to 10 L pouches, about 200 g/m2. 0.5 mm: the 20 to 30 L workhorse, about 280 g/m2. 0.7 mm: expedition and commercial, about 390 g/m2. Each step adds ~100 g/m2 and ~20 percent to film cost, but roughly triples abrasion life. Match gauge to capacity and abuse.
Do not over-spec. A 0.7 mm phone pouch is absurdly heavy. A 0.35 mm rafting bag will not survive. The gauge is the spec buyers feel but never see on the tag.
TPU film spec and ordering ladder
TPU film for dry bags comes in 0.3, 0.5, 0.7, 0.8 and 1.0 mm thicknesses. A 0.3 mm film is 300 gsm and suits packable backpacking sacks; 0.5 mm is 450 gsm and suits 10 to 20 L day bags; 0.7 to 0.8 mm is 650 to 800 gsm and suits 20 to 40 L paddling bags; 1.0 mm is 1,000 gsm and suits expedition and rafting bags. Aliphatic TPU resists UV and stays clear; aromatic TPU yellows but is cheaper by about 15 percent. At MOQ 1,000, a 20 L 0.7 mm TPU bag runs USD 6.5 to 9 FOB.
When you spec TPU, ask for the film brand (Bayer, BASF or equivalent), the melt flow index, and a cold-flex test at minus 20 degrees. TPU is welded by RF on polar grades or hot-air on non-polar grades; the weld bead should be 12 mm wide and peel at 35 N per 25 mm. TPU recycles more cleanly than PVC and does not need phthalate plasticisers, which is why it is the premium default for outdoor brands. Store TPU bags loosely unrolled, because a folded crease left for a year can crack.
People also ask
Which dry bag material lasts longest?
PVC lasts longest under hard abrasion but stiffens; TPU stays flexible longer; nylon is lightest but the coating can wear. Storage and care matter as much as material.
What is the difference between waterproof and water resistant?
Waterproof means it keeps water out under submersion or jets; water resistant means it resists light rain and splashes but will leak under pressure or immersion.
What does IPX8 mean on a dry bag?
IPX8 means the bag survives continuous immersion beyond 1 meter under manufacturer-specified conditions. The depth and duration are only meaningful if stated.
Does dry bag material affect waterproofing?
The material supplies the waterproof barrier, but the closure and seams decide real-world waterproofing. A good film still leaks if seams or closures fail.
What is the difference between TPU and PVC dry bags?
TPU is lighter, softer and more UV-stable; PVC is heavier, more puncture-resistant and cheaper. TPU suits premium packable bags; PVC suits rugged, high-volume bags.
Do TPU dry bags crack in the sun?
TPU has better UV resistance than PVC, but prolonged direct sun still ages any film. Store dry bags out of direct sunlight when not in use.
How are dry bags made?
The body is cut from waterproof film or coated fabric, seams are welded or taped, hardware is attached, and each bag is leak-tested before shipping.
Do PVC dry bags get stiff in the cold?
Yes. PVC stiffens below freezing, which can make rolling and closing harder. TPU stays flexible in cold conditions.
Key takeaways
- Choose TPU dry bag by fixing the activity, size, material and closure before comparing options.
- Verify waterproofing with a stated IPX rating and a real test method, not a label.
- For bulk orders, confirm MOQ, lead time and a pre-production sample before committing.
- Match material to conditions: TPU for cold and UV, PVC for abrasion, coated nylon for weight.
- A physical pre-production sample is the only reliable way to lock material, color and printing.
- Store dry bags loose and shaded, and re-test the seal before trusting them with electronics.
Related guides
- What is a dry bag?
- Dry bag materials: TPU vs PVC vs nylon
- IPX / IP68 waterproof ratings
- Types of dry bags
- OEM dry bags
Step by step
- Decide your priority: weight, cost, cold performance or puncture resistance.
- Choose TPU, PVC or coated nylon accordingly.
- Check the seam method - welded or seam-taped - and the film thickness.
- Confirm any compliance needs such as REACH, RoHS or food-grade material.
Specification checklist
- Fix the specification first - material, size, closure, printing and packaging - so quotes are comparable.
- Verify waterproofing with a stated IPX rating and a real test method, and confirm the batch sampling plan.
- Order a pre-production sample and approve it before bulk production begins.
- Confirm MOQ, lead time, payment terms and the correct HS code before you commit.
- Match the material to the conditions: TPU for cold and UV, PVC for abrasion, coated nylon for weight.
- Ask for a dated test report and a pre-shipment inspection (AQL) for waterproofing and seams.
- Keep the most valuable items in an inner pouch as a second layer of protection.
- Rinse, dry and store the bag correctly to extend its lifespan season after season.
Bottom line
The bottom line is that material choice is a trade-off, not a ranking. TPU is the premium all-rounder, PVC is the tough budget workhorse, and coated nylon is the light packable option. Pair the right film with welded or taped seams and the bag will perform as promised. For "tpu dry bags", this is the summary that matters most.
Frequently Asked Questions
Q1. Which dry bag material lasts longest?
PVC lasts longest under hard abrasion but stiffens; TPU stays flexible longer; nylon is lightest but the coating can wear. Storage and care matter as much as material.
Q2. What is the difference between waterproof and water resistant?
Waterproof means it keeps water out under submersion or jets; water resistant means it resists light rain and splashes but will leak under pressure or immersion.
Q3. What does IPX8 mean on a dry bag?
IPX8 means the bag survives continuous immersion beyond 1 meter under manufacturer-specified conditions. The depth and duration are only meaningful if stated.
Q4. Does dry bag material affect waterproofing?
The material supplies the waterproof barrier, but the closure and seams decide real-world waterproofing. A good film still leaks if seams or closures fail.
Q5. What is the difference between TPU and PVC dry bags?
TPU is lighter, softer and more UV-stable; PVC is heavier, more puncture-resistant and cheaper. TPU suits premium packable bags; PVC suits rugged, high-volume bags.
Q6. Do TPU dry bags crack in the sun?
TPU has better UV resistance than PVC, but prolonged direct sun still ages any film. Store dry bags out of direct sunlight when not in use.
Q7. How are dry bags made?
The body is cut from waterproof film or coated fabric, seams are welded or taped, hardware is attached, and each bag is leak-tested before shipping.
Q8. Do PVC dry bags get stiff in the cold?
Yes. PVC stiffens below freezing, which can make rolling and closing harder. TPU stays flexible in cold conditions.
Q9. How long do dry bags last?
A well-maintained dry bag lasts many seasons. PVC lasts longest in hard use but stiffens in cold; TPU stays flexible but is softer.
Q10. How do I clean a dry bag?
Rinse with fresh water, wipe with mild soap, and air-dry fully before storing. Avoid harsh solvents and keep zipper tracks clean of sand.
Q11. Are dry bags actually waterproof?
Yes, when closed correctly. A roll-top bag sealed with three or more tight rolls is waterproof enough for IPX7/IPX8-class submersion.
Q12. How can I tell if a seam is well welded?
A good weld is smooth, even and free of gaps or bubbles. Pull gently along the seam - a strong weld should not peel or open.
Q13. Do welded seams fail over time?
They can. UV, abrasion and repeated flexing eventually stress any seam. High-quality welds with proper film thickness last many seasons.
Q14. When should I replace a dry bag?
Replace it when seams peel, the film cracks, the zipper no longer seals, or it fails a leak test after a repair.
Q15. When should I use a dry bag?
Use one for any activity near water or in heavy rain - kayaking, boating, camping, fishing, SUP, travel and commuting.
Q16. What are the parts of a dry bag?
Body fabric, roll-top or zipper closure, buckle, D-rings or attachment points, straps or handles, and optional purge valve or window.
Q17. Do dry bag liters equal real capacity?
No. Liter ratings are approximate and the roll-top eats a few centimeters of usable length. Treat them as a guide and size up for bulky gear.
Q18. How do dry bags work?
The body is made of waterproof film or coated fabric, and the seams are welded or taped instead of stitched. The roll-top or zipper then seals the opening.
Q19. Are TPU dry bags eco-friendly?
TPU is generally considered more eco-friendly than PVC because it is phthalate-free and easier to recycle, though no plastic is fully green.
Q20. Do dry bag patches really work?
Yes, when applied to clean, dry material with the correct patch and adhesive. Patches are a temporary-to-permanent fix depending on the damage.