Expert Answers
Waterproofing a backpack

Rob's Question:

Instead of using a pack cover, is there any way to waterproof a daypack or backpack with a product such as Nikwax?

—Rob

Annie's Answer:

	Ask the Expert Annie Getchell Gear expert Annie Getchell believes the key to happiness is buying quality gear and treating it with tender loving care. Meet Annie Answer Archive Gear Forums

That's a tough job, Rob. Frankly, I think you'll be just as happy spending the 20 bucks on a decent pack cover.

Most modern backpacks are constructed with rugged waterproof fabrics (coated on the inside) and bound seams -- they really do keep your gear amazingly dry. What the pack cover (or ubiquitious trash bag) does do is prevent saturation of the exterior fabric, and from inevitable leakage around zippers or bar tacks.

If you have an older pack with unfinished seams, you might consider seamsealing. For this I recommend applying a super-thin bead of Seam Grip urethane adhesive along the cleaned outside seam line. Obviously, this could take a very long time. Once again, the pack cover's pretty attractive. If you're positively determined, however, you can try any number of waterproofing products designed for fabric. Heck, you can even apply Thompson's Water Seal (popular treatment for decks) in a Preval sprayer. I've done this on old canoe packs and duffel bags, and it does help the water to bead up and dribble off.

Still, you can't beat that old trash-can liner for simplicity and price.