Question About Nylon Retaining Water When Wet

I’m sure you could throw a wet backpack on a scale and measure an increase in weight but I can’t imagine ever noticing a difference between wet and dry while wearing it.   If anything, the misery from the 20 versions of Forrest Gump rain will drown out the misery of a few extra ounces on my back.

I made a pack out of a laminate, xpac I believe

I found that it wears out quicker.  the several layers are each thinner

It probably lasts long enough though.  Many people are happy with laminate

Next time, I’m making my pack out of nylon – 210 Robic

Robic 210 and 420 are simple and stout fabrics, but are not stiff like XPac and DSM products, so if you like the bag to stand up by itself when you load it, use the laminated fabrics. As Jerry mentioned, I think you are unlikely to notice water weight any more than you would notice a compactor bag inside the pack, which I would use rather than a pack cover. Pack covers work to repel the water until the water starts to collect in the bottom, then you have a bath tub that you are carrying around. At least that has been my experience. My pack cover stays home now.

The only composite fabric I have ever used is from Dyneema Composite Fabric. It is just personal taste, but I did not like the feel of it or the wrinkles, probably because I was raised using nylon packs. The pack I am looking at uses 300/440d diamond ripstop nylon with PU coating.

Thanks for the posts, seems like any water retention by nylon is minimal.

Lowell

The water retention argument in favor of Xpac is mostly silly.  Most Xpac variants have a nylon face fabric.  Roughed up X50 with the DWR long gone is going to retain a similar amount of water to roughed up 500D cordura with a PU coating inside, until conditions get gnarly enough to fully wet out the fabric.  Then Xpac comes into its own, retains a bit less water weight, and more significantly dries faster as the inside does not get saturated.

DC – impeccable timing, I was rambling through your website yesterday looking for info on this topic and then you posted here. I did not find info on this specific topic on your site, but went down many rabbit holes; really nice writing and thoughtful content!

It seems like nylon plus pack liner will work well enough for many rain conditions, but if the rain is going to be gnarly then a well-fitting pack cover or a poncho would prevent wetting out of the nylon.

Lowell

seems like they’d both retain water weight with, say, something like dyneema x gridstop vs. vx07 but the xpac will retain slightly less due to the thinner face fabric. I assume drying times would be quicker on the xpac. does this matter much? I dunno if it’s top concern when chosing a fabric. about as much as wool socks vs. synthetic socks vis a vis water retention and drying times. something to consider but not worry about

For tents, nylon can absorb enough water to make a substantial difference in pack weight, and it can absorb it from both the inside (condensation) and outside (precip) of the tent, and do so right through a silicone coat.  For packs, I’ve never had this problem, partly due to the DWR coating on the outside of most coated nylon pack cloths.  And partly because the amount of fabric on a pack is far less than on a tent.

Once bought a remarkably waterproof fabric from OWF, but found it had no DWR coat on the outside.  This was solved with a spray can of what was then the best.  But now that we know about the dangers of PFOAs, it might be best to be sure the DWR on the pack is the best at time of purchase.  If needing to refresh the outside of a pack fabric, would use my MM gas mask and do it outdoors, as am the overly cautious type.

I like the look and feel of x-pac. I wouldn’t work too much about wet weight with either. The suspension padding may absorb and retain water as well.

If you wore a poncho like any good backpacker should, your whole pack would stay dry anyway :) Pack covers help but can’t be ri d on to keep critical  items dry. I too am a fan of trash compactor bag liners.