Water proof treating a pack?

The Jansport probably has polyurethane coating on the inside already. Heat wouldn’t be real good for it. I NEVER put PU coated items in a dryer or even expose them to hot water– hand wash in lukewarm water and hang to dry out of the sun.

I imagine you could use some sort of DWR spray on it. Take it outside and spray it with the hose– if the water beads up and runs off (and I bet it will), there isn’t much more you’re going to do with it.

What I would do would be to work on waterproofing what I put in the pack– silnylon dry bags for your clothes and sleeping bag. Less expensive options would be to use turkey roasting bags or trash compactor bags.

A pack cover won’t hurt, but it still isn’t waterproof enough to bet your life on– finding yourself in a bad situation with wet clothes and a wet sleeping bag. You can get two good size Sea-to-Summit bags for the same weight as the pack cover and they can be used in other packs and for day hikes.

I think pack covers are outrageously priced too. With an external frame pack is is pretty easy to use a garbage bag or sheet plastic to cover it. A length of small diameter shock cord and a toggle will help– like a huge and adjustable rubber band.

Right. Generally, pack fabrics are already waterproof. Seams and zippers, and any unprotected openings are where water gets in.

You can seal the seams to slow water’s progress inside, but I’ve only found this effective on simple pack designs with relatively few seams–rare these days. Unless zippers are of the water-resistant kind, or have aggressive storm flaps, there’s little you can do to prevent them from wicking water inside.

Pack liners work well protecting the main compartment–trash compactor bags are cheap and effective–but leave items in pockets unprotected. They also don’t prevent water from pooling in the main compartment, which is messy and eventually heavy (some packs have drain holes to let water back out).

Pack covers work well, but shoulder straps and waist belts still get soaked, as does any back padding. Generally, only a poncho will protect the entire pack.

Waterproofing a backpack is not reliable. As stated by others, seams and zippers will leak. I’m sure this article is old hat to most here but I go this route:

http://jwbasecamp.com/Articles/DryGear/index.html

I’m not quite as fastidious as Jim is but I do double bag my sleeping bag and extra clothes. I use a pack liner for all the contents, with my camp clothes and sleeping bag at the bottom in a second plastic bag (duct-tape reinforced oven turkey bags work great for this). Anything in a pocket that needs protection get zip-locked. I’ve never had anything get wet through many hours of heavy rain. If you’re worried about total immersion you might want to look at individual drysacks like those from Sea to Summit.

Thanks, guys. All of your insight is helpful. AFter reading and considering, I think I’ll just use a garbage bag as a pack liner, then the usual stuff sacks of plastic and wetbags. I always have a poncho, so I sort of forgot about that. Thanks again.