Waterproofing a Backpack

I recently got a new Jansport backpack for school and was thinking about applying some waterproofing to protect the books that cost almost as much as my tuition. Is there a particular product that works better than the others? I looked around REI today and saw a few that looked promising, but I've never done this before and it's hard to tell from the packaging what each will really do.

Thanks in advance,

Chris.

Well, I know you need to use two different products. One (usually a roll-on) to seal the seams, another (usually a spray) to seal the fabric. If you don't do both you could still get water inside.

You should contact the maker of any product when contemplating waterproofing. The industry uses many common materials, but may have special finishes or assemblies that affect waterproofing. Remember also, that a totally waterproofed bag may actual suffer some degree of condensation INSIDE. During my studies I simply used a heavy duty plastic bag liner in my cordura nylon daypack. I am puzzled. Many of my textbooks were such dry reading a local botanical study of Redwood Forest fog drip transpiration was adversly affected <img src="images/graemlins/grin.gif" alt="" />

I have a home remedy type of recipe for waterproofing canvas. I have never tried it so I can' tpersonally vouch for it's effectiveness. It's oil based so it may mar your colors and leave an unpleasent scent or feel to the bag.

3c. soybean oil
1 ½c. turpentine

Mix and paint or spray on canvas
Repeat as necessary if exposed long periods of time

dust with talc or powdered chalk

Thanks for all the advise guys. I probably won't get to it before the semester is over, but now I at least have a starting point.

PS.
Chris, trust me, there are some messed up botanical studies on this coast too <img src="images/graemlins/wink.gif" alt="" />

Thanks again,

Chris.

If I were you, I would invest in an Outdoor Research Advanced Hydroseal Stuff sack. They're not that expensive ($30 or so bucks), you can put other things in it (sleeping bags, etc.) its made out of coated nylon (so you can compress it down easily), and they come in several sizes. I have put all kinds of things in there and while I might not be able to drop it in a lake and have it dry, it will definetly take on a rainstorm without a problem. I've never had a wet sleeping bag with them before.

It occurs to me that if you are wearing the backpack, your poncho should cover it and protect it from water. If you are not wearing it, any old piece of plastic or waterproof tarp could be wrapped around the backpack for protection from water.

Bountyhunter

2 things. i know they offer slip-on type covers for packs to keep em dry. if your looking for something just to apply to the bag itself, i think Scoth-Guard (starch) makes water-proofing stuff too....check it out. i used to spray the stuff on my boots.