It's been raining for a few days, so I retrieved all the 35mm film canisters sitting in my woods for an evaluation. Here are the findings:

Three of the canisters were Kodak, black base with grey cap, with the old style cap that's smooth on the bottom. Two were dry inside, one was wet.

Three of the canisters were Kodak, black base with grey cap, with the new style cap with ribs on the bottom. All three were dry inside.

Three of the canisters were Kodak black bases with milk carton caps on them. These milk carton caps snap on just like the original caps and have a smooth bottom and a thin lip around the edge. All three were soaked inside.

Three of the canisters were Fuji, white with a knurled edge on the cap. Two were dry inside, one was wet.

One canister was of unknown make, black base with an orange top. Looked like it'd seal well to me, but it was wet inside.

CONCLUSIONS:

Well, the first conclusion is easy: the milk carton caps don't work.

Perhaps the next firmest conclusion: 35mm film canisters are not reliable. One might conclude that the newer style Kodak are better because all three remained dry, but with this size sample that could just be luck. One would hope, of course, that when they redesigned their container they improved it.

I would have been very surprised that the Fuji containers suffered a failure if I hadn't already had one fail in the field. These things look perfectly watertight to me. Looks are obviously deceiving.

NEXT:

I think I may just close up the successful containers again and toss them back in the woods. The idea would be to see if the same container would stay dry time after time, or whether it's just random each time you close it up.

I might also put new slips of paper into the failed ones and try them again as well, for the same reason.

I'm also thinking of modifying some containers to see if I can get them to seal more reliably. For the Fuji containers, I'm thinking of tying some fine wire around the upper edge of the base to see if I can compress the seal more securely.

I'm a bit miffed about the new style Kodak being successful because I have more trouble trying to bond a stamp to the underside of those -- in fact, that's why I've been trying the milk carton caps. Of course, if these canisters prove truly reliable, I could always revert to another use for them, namely taping two together butt-to-butt and putting a log in one end and a stamp in the other.

Whatever kind of film canister Gilda the Goldfish is in seems to be successful. Of course that stamp is up off the ground. Maybe that makes a difference?

Thanks Kirbert for taking the time to test these out! I enjoyed reading your results. I would have guessed these would have faired a bit better. Nothing like a good experiment to prove us wrong.

jackbear

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Whatever kind of film canister Gilda the Goldfish is in seems to be successful. Of course that stamp is up off the ground. Maybe that makes a difference?

That box is up off the ground, under cover (of sorts), and is sitting upright if each placer has replaced it properly. The sitting upright is a biggie. Lots and lots of containers would pass these tests if sitting upright, since the lids are often shaped so that rain will run off the sides without getting in. Unfortunately, those same boxes will still suffer in the long run, because even if rain cannot get in, the humidity of the surrounding outdoors (here in FL, anyway) will gradually cause the contents to get musty and possibly even moldy. All in all, it'd still be better if the container provided a positive seal separating the inside from the outside.

Hence, for these tests, I've been laying the containers on their sides, inviting rain to get in if it can.

It really doesn't seem like too much to ask of a container. I'm still surprised by how common failure is. I mean, there are a lot of containers out there that clearly don't even try to seal, loose-fitting snap-on tops and whatnot, but these containers I've been testing all look like they're actually supposed to seal. Lock&Lock has remarkably little competition!