DIY Chew-Proof Bear Bag
Four years ago when fellow hiker Lee Fields and I were preparing to do a long distance hike on the AT, I ran across a blog that mentioned someone making a "chew-proof" food bag from the exploded airbag of a car. These airbags are made of a combination of materials (like Spectra) that are extremely resistant to tearing and cutting. The material from these bags resembles the commercially available Ursack (at least the older version). Since my wife had recently given me a few sewing lessons on her machine, I decided to give it a try.
After some trial and error, I came up with a reasonable solution to making these bags that seems to work well. The good news is that after using this bag for over 1,500 miles in the last four years, I have yet to lose a morsel of food. In fairness I have not had to test the "bear-proof" nature of this bag to date, however I have had a few encounters with mice and other rodents around shelters with no damage to the bag or contents. I will therefore will continue to call this "chew proof" and hope that I don't have an opportunity to test it further against bears!
An added bonus is that this DIY project is nearly free!
How to Do It
The first step is to visit your local auto junkyard. Take a utility knife with a new blade. You are looking for a car that has a deployed passenger-side airbag . The airbags are substantially bigger than the driver-side bag that deploys from the steering wheel. The ones that I have found best for this purpose are from late-model American sedans and SUVs.
Once you locate a bag, you will need to use the utility knife to separate it from the car fairly close to the dash. Note that there are often sharp edges around the airbag opening, so gloves are a good idea. On my last trip I located and recovered four airbags in about 15 minutes and the junkyard let me have all of them for $1 (which was actually the entrance fee).
I have found the airbags provided by different vehicle manufacturers can be vary substantially. The type that appears the most durable to me (and is closest to the original Ursack material) has a "rip-stop" grid pattern. I would strongly suggest that you look for this type. I have had the most success with Ford cars, trucks and SUVs but am not sure that this material is limited to that brand.
After bringing the material home, I usually soak it in a bucket of bleach and water and then let it dry in the sun. You then have the option of either seam-ripping the material (which is a long process) or simply cutting out what you will need from the largest panel. If you decide to cut the material, I have found that using a cheap wood burning tool does a great job with sealing the edges of the material while it "cuts" (cutting with scissors tends to make the fabric fray). If you use this method I would suggest doing it with good ventilation as the fumes that come from melting the fabric can be a little overwhelming.
The size of your bag is a personal choice depending on your needs. I make mine the approximate size of a waterproof 13L bag that I have. In practice what I have found works best for me is putting the chew-proof bag in a waterproof stuff sack when I am hanging it outside and rain is likely. The airbag material is porous and I don't like putting the wet bag in my pack in the morning. In shelters and on dry nights I typically forgo the waterproof bag or put it inside the chew-proof bag.
The final dimensions of my square-bottom bag (laying flat) are 13" wide x 16" tall and this usually holds 4-5 days' worth of food for me. The material you start with will have to be larger to allow for the seams, and the overage depends on the type of seams you intend to use. The first time I made a bag like this I used a simple seam, but now use a sturdier seam which helps prevent fraying. Using a rolled seam, you will need a piece of fabric 23"x28" to start. I can easily get a piece that size out of the type of airbag that I like to use, but it is possible you may have to join two pieces depending on the airbags you find.
The directions (located at the bottom of the article) provide step-by-step instructions on making the bear bag. Once you have the large panel cutout, making a bag is usually less than a one hour project.
A final note- I use OP Saks inside of my bear bag to hold my food, which I believe helps contain food odors and further discourages attention from animals.
My bag with the optional hang loop weighs 4.2 ounces. I know there are bear bag solutions available that weigh much less but I am happy with the tradeoff given the additional protection (and peace of mind) that this bag provides. I like to eat- and more importantly I HAVE to have my morning coffee, and the confidence of knowing my food will be available the next morning is worth the extra weight to me.
Check out DIY Chew-Proof Bear Bag Steps
This post was contributed by former Gossamer Gear Trail Ambassador Ken "DripDry" Holder