I am leaving today on a backpacking trip. A friend was supposed to lend me some empty film boxes to store exposed film, but unfortunately this fell through.
Are there other ways to store exposed film while on a trip?
Glassine envelopes and a small pair of scissors. Cut notches in a corner for different developments such as one notch for N, two notches for +1, three for +2, four for -1, etc. This way they can all get fired into one box, are protected from scratches, and exposure info can get written on the envelope itself. I've used this method for up to two months while sea kayaking and never miss-developed a sheet.
I use a divider system with tabs along the side for -2, -1, 0, +1, +2 and one tab along the top divider, so I don't accidentally flip the stack upside down, and then I can use just one box for unloading. If the box fills up, on a longer trip, I can split the stack as I unload boxes of fresh film and make new empty boxes.
All I meant was to use the interior bag of the unexposed film until you free up the box for the unexposed film. It is not necessary to use the interior bag with the unexposed film.
Freestyle photo sells black plastic bags and corresponding cardboard "film mailers" I transfer my exposed 4x5 film to their 5X7 then triple fold and then place inside one of the mailers. You can either pack may of these for each set of exposures or place all the n-1 in one bag all the n-2 in another etc etc.
Last time i purchased these they cost $.59 for each for the bag and mailer. They come in sizes up to ULF. There is no 4x5 cardboard mailer the smallest is a 5X7.
Also if you happen to have 4X5 film boxes kicking around that will work with the black bags too.