Re: Shinken Rust Problem
Yeah, you are of course right -- I didn't expand enough. Those who wrap them will do it only on a dry day. Oil it and wrap it completely *and* tightly sealing it in. And it's still not a long term solution, really, but more for those who are leaving it for a couple months. Oil it well.
Better though, IMHO, is to simply clean it periodically and reoil. Or if it's not a high end blade in professional polish just use something like breakfree CLP. That stuff is fantastic.
But also keep in mind that a properly fit saya done by a professional should create what is for all intents and purposes a fairly air tight and stable environment. I'd keep it away from temperature variations, but really if it is done correctly it shouldn't be much of a problem.
I have a customer who lives damned near on the ocean. He has one of those vacuum sealing units. He'll clean and oil the blade, replace it in the saya, then pack the sword in a normal fabric storage bag. He'll toss a couple desiccator packs (the type you buy to put in gun safes) in a long bag (you can buy the seal-a-meal bags in rolls) and seal it up. Voila, sealed environment, dry, etc. I don't know what effect it might have long term on the wood of the mounts, but for keeping the blades rust fee it seems to work for him.