As tpnl noted, it looks like the urethane coating is wearing off. To add to the great answers/information already posted here:
Most of the fabrics we use are coated with a thin layer of urethane plastic on the reverse side of the fabric (typically, the inside of the bag). This coating, combined with the DWR (durable water repellant) treatment on the face (exterior) of the fabric helps keep the worst of the weather away from the contents of your bag.
Relative to the longevity of the fabric itself, as well as the other components of the bag, both the urethane coating and the DWR treatment might fail earlier than we'd prefer. Over time and use, the DWR wears off of the surface of the fabric: it's invisible, so you can't tell that it's gone until you start seeing surface water soak into the cloth itself. We sell Nikwax® Tent & Gear SolarProof® as an after-market, applied-at-home treatment that allows you to more or less renew the original water repellency of the fabric (you can find Nikwax® at most outdoors stores so if you're not already buying something else from us you may just want to pick it up locally.)
The interior urethane coating, however, is more problematic, in that there isn't (so far) any good way to renew or treat areas where the coating has worn away. We work closely with our fabric mills, and when we show them bags that have had their interior coatings wear away, they shake their head and say "yep, that happens sometimes". They offer no help or recourse for us, and so far we have found no acceptable alternatives.
It's worth noting that fabrics made in countries without many environmental regulations may be coated with more durable coatings than the fabrics we use that are fabricated in the U.S. or Japan; we choose a slightly less durable coating over something that could be considerably more toxic to our planet and us humans.
That all said, we have had an occasional roll of fabric that seemed to have had particularly not-so-good coating, in which either the thickness of the coating or its adhesion to the base fabric was less than optimal.
If anyone has a bag that has had the coating substantially fail within the bag's first year of use, we might be able to replace the bag entirely if it's adversely effecting your use of the bag -- [email protected] if that's the case and we'll work the details out.
P.S. Interestingly, we have found that sun exposure, high humidity and air pollution can speed up the process of the urethane coating wearing off.
Most of the fabrics we use are coated with a thin layer of urethane plastic on the reverse side of the fabric (typically, the inside of the bag). This coating, combined with the DWR (durable water repellant) treatment on the face (exterior) of the fabric helps keep the worst of the weather away from the contents of your bag.
Relative to the longevity of the fabric itself, as well as the other components of the bag, both the urethane coating and the DWR treatment might fail earlier than we'd prefer. Over time and use, the DWR wears off of the surface of the fabric: it's invisible, so you can't tell that it's gone until you start seeing surface water soak into the cloth itself. We sell Nikwax® Tent & Gear SolarProof® as an after-market, applied-at-home treatment that allows you to more or less renew the original water repellency of the fabric (you can find Nikwax® at most outdoors stores so if you're not already buying something else from us you may just want to pick it up locally.)
The interior urethane coating, however, is more problematic, in that there isn't (so far) any good way to renew or treat areas where the coating has worn away. We work closely with our fabric mills, and when we show them bags that have had their interior coatings wear away, they shake their head and say "yep, that happens sometimes". They offer no help or recourse for us, and so far we have found no acceptable alternatives.
It's worth noting that fabrics made in countries without many environmental regulations may be coated with more durable coatings than the fabrics we use that are fabricated in the U.S. or Japan; we choose a slightly less durable coating over something that could be considerably more toxic to our planet and us humans.
That all said, we have had an occasional roll of fabric that seemed to have had particularly not-so-good coating, in which either the thickness of the coating or its adhesion to the base fabric was less than optimal.
If anyone has a bag that has had the coating substantially fail within the bag's first year of use, we might be able to replace the bag entirely if it's adversely effecting your use of the bag -- [email protected] if that's the case and we'll work the details out.
P.S. Interestingly, we have found that sun exposure, high humidity and air pollution can speed up the process of the urethane coating wearing off.
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