View Full Version : Seam seal backpack?
Mfrenchy
01-24-2012, 19:09
Should I seam seal my backpack? I'm thinking yes, but not sure if it is worth the effort.
RWheeler
01-24-2012, 19:13
Is the fabric of your backpack waterproof?
Mfrenchy
01-24-2012, 19:23
It is an Osprey Exos 46. I believe it is just ripstop nylon.
No. Use a pack liner and/or cover. Most coated pack fabric will be stretched with use and will usually delaminate from whatever coating is applied, causing it to leak, eventually.
Silnylon fabric is not completely waterproof, either. Under pressure (like that between your back and the fabric), it will allow some seepage.
Laminated fabrics (like those used for kayak storage sacks) are heavy and seldom used for backpacks (but are completely waterproof until the laminate wears thin).
Cuben fiber is completely waterproof, but not abrasion resistant, so it will eventually leak, too.
Pack covers can be replaced relatively cheaply once they leak (I have a few burn holes in one due to a nearby campfire).
Caveat: Pack covers do not protect the fabric against your back from leakage (again, use a liner and/or multiple waterproof storage sacks).
ALLEGHENY
01-24-2012, 19:29
Best to use liner and or dry bag.
Mfrenchy
01-24-2012, 19:45
Just read the pack care page on the Osprey site and they recommend spraying it with a nixwax water repellant occasionally. This is what I was thinking of doing just for redundancy, as well as having stuff sacks for everything. Thought the seams would be the weak spot.
Just read the pack care page on the Osprey site and they recommend spraying it with a nixwax water repellant occasionally. This is what I was thinking of doing just for redundancy, as well as having stuff sacks for everything. Thought the seams would be the weak spot.
Treating the outside of the bag will repel water, which, when soaked into the fabric, makes the pack heavier. This would be the logic of that recommendation as far as I can see.
ChinMusic
01-24-2012, 19:52
Should I seam seal my backpack?
NO. For one, the seam seal itself would weigh more than a pack cover.
Agreed No, why would waterproofing the seams, keep water out of a backpack that isnt made of waterproof fabric.
what if your pack is waterproof then u seam seal it and your water breaks open, it would just pool at the bottom of your pack, or if stuck in rain for many hours and the top is open, you would be carrying a pack full of water. I'm not saying this is certain to happen its just a funny thought to me :)
what if your pack is waterproof then u seam seal it and your water breaks open, it would just pool at the bottom of your pack, or if stuck in rain for many hours and the top is open, you would be carrying a pack full of water. I'm not saying this is certain to happen its just a funny thought to me :)
I think youd notice though right. But it would be funny to see one of those UL homemade cuben fiber guys hauling 20 lbs of rain water in his pack.
aaronthebugbuffet
01-24-2012, 22:08
your water breaks :) shouldn't that be in the ladies' forum?
No reason to seam seal a water resistant pack. Use a liner or whatever.
As Tinker said the pack having a resistance to soaking up water will help with not picking up a lot of additional weight.
stranger
01-24-2012, 22:08
It depends on 'why' you want to seam seal the pack, and they the question of whether or not it will make the pack waterproof. If the pack IS NOT made out silicone impregnated nylon, so using some form of packcloth, ripstop nylon or cordura, Seam Grip will adhere very well to the fabric and will hold for many years, if:
- the pack is already used and the seams have had time to stretch
- the pack is clean and the Seam Grip is adhering clean fabric
- you do a thorough job (alot of Seam Grip, alot)
However, will the pack be waterproof? Well not if it has a zipper, and not unless you can completely, 100% get to all the seams, which is very unlikely. Then there are the seams you can't find as well. So assuming you can do all that, and do it near perfectly, and your pack doesn't have a zipper anywhere...it might work. Of course, another very simple option is to get a packcover and keep your 'can't get wet' items in roll down silnylon, seam taped sacks or pack liners. I recommend packcovers just because even if your stuff inside is protected, exposing your 50-60 litre pack to water will absolutely make it alot heavier, I always want to keep the exterior of my pack as dry, and light, as possible. As the saying goes...."Oh yeah, how much does it weight when it's wet?"