How can I re-apply a PolyUrethane (PU or TPU) lining on a (formerly) waterproof fabric whose original lining has delaminated?

My trusty laundry bag's waterproof lining has delaminated such that it now leaks water out of the bottom faster than it fills with water from the faucet.

The fabric of the bag is made of (green) nylon, which is intact. Only the inner lining of (white) TPU is wearing away, causing the bag to leak. See photos below.

photo of the outside of a green dry bag photo of the white inside of the dry bag with the TPU has worn away in some places
This 4-year-old, 20L Sea To Summit "Lightweight Dry Sack" is made out of 70D nylon. The nylon material is intact and has held-up well to years of use The inside of the same dry bag has a white TPU coating with a 10,000mm hydrostatic head. This waterproof lining has delaminated from the nylon, making the dry bag no longer waterproof.

I figure if I could somehow strip the TPU off the nylon and re-apply a waterproof PU layer, then the bag should be waterproof again. How can I do this? Is there any other way to repair this bag so that it's waterproof again?


1 Answer 1


Small areas of damage can be repaired with tape (for example Tenacious Tape), but even with a very robust tape this is temporary in practice. Once the delamination starts it will continue. I repaired a few leaky, obviously damaged patches on my drysuit, but within a few months it became clear that large areas had become porous.

In the field, I'd use duct tape (I have some in my bike tool kit and kayaking emergency bag; I often grab the latter for day hikes). Once you get home, it's only fit to be used as a splash-resistant stuff sack

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