Layering oven bags with a cotton cloth inside the bucket is actually a clever idea, especially if you’re working with what you’ve got on hand. I’ve tried something similar, using old clean pillowcases as an extra liner around the oven bag before sealing the bucket. It helps wick away a bit of condensation and adds another barrier if anything pokes through the plastic. So far, my flour and beans have stayed dry (well, except for the time I stored the buckets in the shed and some sneaky ants found their way in—now I always check for tiny cracks!).
For those worried about smells or moisture, tossing in a cheap silica packet or even some dry rice in a paper sachet can really help. I haven’t shelled out for Mylar yet and honestly, the DIY approach holds up pretty well for me, at least for 1-2 years’ storage.
Curious if anyone’s had luck with bulk dry milk storage? I’ve only ever managed to keep it from clumping by double bagging and squeezing out as much air as possible, but it always feels like a losing battle once summer humidity rolls