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Waterproofing inside of backpack

Is there a product I can use to re-waterproof the inside of my backpack? The sealant that is inside now has been peeling off for months.

There are such products, but they are tedious to apply, mostly due to the necessary prep work.  Furthermore you really can't get a lasting seal in seams, since the forces of gear shifting about exerts considerable force  from many directions on these stress points, causing the WP coating to delaminate. 

I just resort to stowing gear in large plastic bags, or better yet, cover my pack with a  large 3 mil trash can liner bag.  The large bag is the most effective protection I have ever used, better than the OEM water proof coatings and expensive pack covers. When it comes time to cover up, I disconnect the top end of the pack straps, roll the bag over my pack, pop holes in the bag where the straps will pass through to attach to the pack, reattach the straps and I am good to go. The bit regarding detaching and reattaching the shoulder straps is a minnor inconvenience for the quality of protection you get from the system.  My packed gear never gets wet from falling rain or snow.  You will still need to use dry sacks for steam crossing immersions, however, but that is true for practically all the other alternatives.  If you get a hole in the bag, just duct tape the hole(s).  Retire worn bags as needed.  I found this rain system requires a slight change in how I pack.  Normally I place items needed during the hike at the top of my pack or in the side and back pockets.  But since the open end of the bag down is at the bottom end of the pack, I pack items needing easy access at the bottom of my pack or in the lower side pockets, so I don't have to completely uncover the pack for access.


Read Ed's post. 

It is possible to get some really strong plastic bags from canoe equipment companies like Duluth Pack in MN.  I like contractor plastic bags to cover the pack.  Sleeping bag gets its own plastic bag. 

What about a compacter bag to line your backpack and contents

That's what the Dulut Pack bags are desinged to do. 


I’m in the same boat right now. Spent the better part of today completely disassembling two older (22+ years) backpacks and washing them in Nikwax Tech Wash as a first step in trying to get them back up and running after too many years hung in the workshop.

One is my trusty old Dana Designs ArcLight Direct. The other is an Osprey Zephyr. I noticed both packs had a funky odor coming from them when I took them down off their hangers. (No, there weren’t any creatures that died in them or nasty, forgotten items left behind from past trips) I also noticed the inside panels of both packs were starting to peel/delaminate. Evidently, the source of the smell is the polyurethane coating on the interior lining of the panels breaking down.

After much research, I am still not 100 percent sure what method I will use to reapply some sort of PU or waterproof coating. I do plan on trying to strip off all of the peeling stuff on the Osprey, as it is by far the worse of the two. The Dana pack just has some small areas that seem slightly degraded...and others that appear weathered more than actually peeling.

I have both disassembled packs still drying now and will see how they are tomorrow. I will say the Tech Wash did the trick for getting the smell out. I may try Nikwax Tent and Gear Solar Proof spray once I strip away all the peeling remnants and see if that’ll work. Both packs are worth the time and effort to try and save, as they were both made by hand in Bozeman, MT and Dolores, CO respectively. The craftsmanship on the Dana is especially impressive, with the chalk marks denoting size and model etc still visible upon disassembly. (I also recall it had a paper/cardboard tag attached when I purchased it that had the person‘s name and the date of completion handwritten on it!!)

I’ll post an update once I get to phase II of this project!

Stripping the Osprey, although tedious and time-consuming, as others have said elsewhere, was made a tad easier with a brush attached to a drill & some rubbing alcohol.

The edges and corners were done by hand with a small brush and a t-shirt.

Cordless vacuum came in handy throughout the process. Now I just need to figure out what to replace the PU coating with!

Also, I should point out that the smell was completely eliminated by using Gear Aid Revivex Odor Eliminator after all the old coating was stripped out.






All coatings delaminate with time.  Just strip the gunk off and continue to use the pack.  Waterproofing is best assured by bundling individual items securely.

I use plastic bags for items that need a tight seal. 

The Osprey has since been passed on to someone who needed a pack. Hope it provides him with many years of enjoyable time on the trail!

Hi Garypalmer

Based on my experience i think u can try this method.

Four things you need to do a backpack waterproofing.

  1. Container,
  2. Mineral spirit from your any local hardware store
  3. 100% clear silicon
  4. A paint brush

In First pour the mineral spirit into a pot, then stir it with 100% clear silicone in it until the silicone dissolves. Now cover it with a lid and shake it
Mix very well. Then you have to paint the bag well with the help of paint brush. After painting, it has to be dried approximately 24 hours.  After This time it has become waterproof.



In case anyone needs to remove the sticky residue that appears when waterproofing on jackets (& perhaps tents) starts breaking down—

The sticky residue can be removed with Borax.  Soaking an item in water & Borax dissolves the gummy residue.  No rubbing necessary.  Just rinse afterward.  I tried oil, then vinegar& water, Fast Orange Hand Cleaner, Ajax cleanser.  The only thing that worked easily without scrubbing or scraping was Borax.  

So, Diane.  Does the borax remove ALL of the waterproofing or just the stickiness??  All ready to go with the borax , but the waterproofing is still intact so I don't want to remove the waterproofing and I could live with a little talcum powder :)  TIA,  Bob

Or anyone else who has tried it? 

September 23, 2021
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