Bag Waterproofing

So I bought a Swissgear backpack to haul around my lappy and other stuff, and love it. However, I live in Seattle, and that means lots of rain. Some of the stuff in my bag got kinda damp the other day and the rain was only light. Does anyone know of any sort of ruberizing spray or something else that you can apply to cloth to waterproof it?

 

http://www.rayandrain.com/

we have one of those cloth over hangs that you can retract when its not sunny and use this. You can find stuff at like sketchers or other shoe stores also. Your best protection is simply not to get it wet.

If your using a back pack , I'd spray it and then also have a second sleeve or something for your laptop and spray that too.

 

Buy some thin rubber, all you need to do is cut it to the right dimensions, and get a heat gun. You will fuse the gaps between the threads with rubber, which is naturally waterproof.
My military bag has a complete inner rubber lining, which has kept the water out for 3 years. Every once in a while some of the rubber will come loose, but the heatgun fixes that right up.

K-TRON

 

Yes, not getting it wet in the first place is a great idea, but that's kinda hard when walking around (the whole reason I got the bag to begin with) in the rain, especially when there is strong wind as well, as is sometimes known to happen. The laptop is fairly easy to keep dry as that sits in the pocket against my back and gets reasonable protection from the umbrella and my back, but the papers and stuff in the other pockets have a less advantageous position. I'll try that spray you posted. The ruberizing procedure seems a bit intense to try unless the spray fails. Thanks for the suggestion though, I'll keep it in mind.

Edit: Do you know if the Ray and Rain stuff acts like a glue at all (will I have to mask the zippers when I apply it)?

 

it doesn't seem to act as a glue , I would still mask the zippers though.

 

How about using ziplock bags and plastic document folders to protect your stuff? Or just keep a bin/trash bag liner in your backpack so that you can cover up the whole lot during a downpour! I don't need to do the latter myself, as my Mandarina Duck bag has its own integrated rain jacket hidden in the back.

 

Go talk to the folks at REI. They do this stuff all the time for Backpacks.

 

well, you first need to find the source of the leakage...

3 basic elements of a backpack/bag that is prone to water migration is as follows:

1) strongest protection available here, is the fabric. most bags use a heavy coat of polyurethane on the back side of the bag... of course, without any protective layer behind it, it's prone to wear and tear and basic rubbing by the contents will make this peel and hence render it water permeable in due time.

2) seams: fabrics are sewn together and when sewn, the threads also acts as a wick for transporting water... and the needle holes will also help move moisture.

3) zippers: these are basically plastic molded teeth or nylon coil teeth and offers very little protection from moisture.

basically, there are waterproof zippers out there but it still has a thick coat of polyurethane membrane either coated or laminated.

some bags actually have inner placket to protect a bit, but still does not offer protection fully.

the fabric protection spray is good option for the fabric and perhaps even the seams... but not permanent and it's rating is for only minor exposure to rain... it will wash out and it will need reapplying.

the best thing to find out there is a bag cover... basically, a good waterproof fabric that has elastic bindings so it covers and holds in place... think of a big version of a showercap... this will cover the 3 points very well and you can remove it and pack it in a small ziploc when you're done.

i've seen electronics bags come with this... you may be able to find it on most outdoor specialty shops.

 

by the way, the sprays and topical treatments are not glue... it's a PTFE solution that will coat and dry on your fabric to make the sufrace really smooth and soft, hence water will roll off... this is called Durable Water Repellency and it's rated by how many washes it takes to see % of permeation of fabric. they are not permanent.

 

I'd prefer avoiding using plastic bags. The thing was I was walking around in what was not even a really heavy rain, and when I got home, I found the bus schedule in the outter pocket was soaked about 1/2 way up from the bottom of the bag. I'm not trying to ruggedize the bag, just make it practical to use in real life, were I have to walk around city streets in the rain.

 

I'm telling you, rubber is about the easiest way, You can buy strips 4" wide, by a foot long at a good hardware store. A heatgun will yield easy application, I would assume a hairdryer would work as well. The stuff I used is like heatshrink tube, its great, and takes a few minutes to reseal the surface.

Only thing I would worry about is the material your bag is made out of. My bag is heavy canvas, so its not going to be affected by the heat.
A nylon bag or any of those plastic composite materials may get permananetly damaged by the heat, something to worry about.

Otherwise I have never found a spray which actually worked. I am sure KingHong knows what he is talking about though, he does this stuff for a living. King, can you give us some product names?
I wouldnt mind trying something which would may work.

K-TRON

 

Yeah, I would imagine that this bag is loaded with synthetic fibers, heh. If I can avoid heat, I think it would be a good idea.

 

Sup K-Tron!

you can google for water repellent spray and find lots of links... but here's one from REI.

as for bag covers.. this is what i would recommend... least amount of work and does not mess with the aesthetic appeal of a bag.
some topical treatments will darken the color or even leave darkspots due to uneven coating.

this is the most guaranteed way of keeping contents dry... the fabric is waterproof and there is no seams to deal with...

 

yes, most common fiber used in bags is ballistic nylon... it does not like heat that well... even cordura nylon from DuPont... not so good with heat.

polyester used in zippers as well... even more worrysome when it comes to heat.

plus... K-Tron, love you bro... but rubber stinks and leaves black stains.

 

K tron is a nerd. He's probably got a few tricks up his sleeve for these dilemmas.

I'm too lazy. I'd just end up buying a waterproof bag from REI.

 

The rubber literally smells when you heat it on, but its not really that bad. It works very well, at least on the heavy canvas material my bag is made out of.
Being that your bag is synthetic, I would listen to what King hong has to say about it.

I dont know, but maybe contact DuPont, they have some crazy teflon products out there, maybe they can suggest something as well?

The only other thing I can think of is this tube of stuff I have in my room. I got it at my local Lowa boots retailer. I think its called "G-WAX Cream" - It comes in a blue tube
It is a petroleum like substance which you rub on, it works on my leather boots, makes them a bit darker, but the water bubbles right off.

K-TRON

 

There are literally 100s of products at REI for waterproofing bags and such. You can use them on tents, bivouac sacks, tarps, backpacks, hats, etc etc

Considering you are in Seattle...

 

Yeah, I was just thinking that. I might just hit the REI store (and maybe the Columbia outlet) some time over the next few days and see what's what there. Thanks to all of you guys for your help.

 

If anyone is interested, I ended up buying a 20qt bag cover from REI. It cost 20 bucks, is nice and small (so it will now live in the pocket it is meant to protect), and looks like it will work out just fine. Of course the danger of shopping at a store... I went to buy a 20 dollar bag cover, and now I'm thinking about buying a $600 bike.

 

REI is the best place. I like it more than Best Buys.

 

I just picked up an STM backpack from ebay. The guy on there that sells the 17" version has many listings for $55 or best offer... I offered $40 and my pack came today. It is awesome. It has a handy rain cover too. These bags are $120 at my school.