humidity and saya

[Kuri]

I just finished an iai session under some exteremely humid conditions. It felt like I stepped out of the shower with my gear on and didn't towel off.

Getting to my quiery. Halfway through training, sliding the iaito all the way into the saya became a bit of a task. Just before the habaki enters the saya, it feels as thought there's a blockage. And the feeling is the same all the way to the tsuba. This didn't happen before, so I'm assuming that that the humidity has made the timber expand, constricting the free movement of the iaito. I bought it about 10 months ago, so I'm assuming it hasn't experienced such humid weather before (sitting in an air-conditioned shop).

Has anyone experienced this before, or can give me some advice on what can be done?

[alexpollijr]

Hi there.

I live in a very humid place (yes, my gear stinks a lot) and I have a Iaito but never had this sort of problem. I don't think that humidity has done it, unless you let your sword in very humid spaces.

Cheers

[lewis]

I grew up in Kansas City, where the humidity is inescapable. And would alternately practice iai at college and at home (on breaks) throughout college. What happened could easily have been caused by humidity swelling of the wood in the saya. Such problems, especially with precision wooden equipment such as musical instruments, are well known. Personally, the problems I had were the saya splitting when it dried out (and shrank) after being in KC all summer.

If humidity is the cause, there isn't much you can (or should) do about it, except to keep using it. If you keep using it in the humid conditions, it will gradually loosen up over time. (if you don't it may swell shut and bind). If you return to a dryer clime, it should return to its old shape - but the use while swollen may have caused increased wear.

My experience is that any attempts to repair (through sanding, filing, etc.) always cause more harm than good. And you don't want to be the student whose iaito falls out of its saya accidentally. At least right now, you don't have that problem, which is far worse.

[Kuri]

Thanks for the advise. After returning it to the cool and dry airconditioned environment of my apartment, it has returned to normal (12 hours). All is well, maybe......

Unfortunately, timber is very bad at returning to it's original state after been subjected to different loads and deformations (ie. bending, twisting, change in moisture content, ....) The changes tend to be permentent (never returning to the original state). Can anyone comment on the long term effects of such extereme environemental conditions (hot humid summer/cold dry winter)

[lewis]

I glad it recovered. I was thinking, the cause may also have been your sweat - rather than the humidity directly. If that is the case, your problems shouldn't be as bad. Although, you have about as much control over sweating as the humidity - contact with sweat during practice shouldn't be as bad because the water shouldn't penetrate as deep and will only affect those areas in direct contact with the water. Humidity will affect all the wood and create a lot more stress on the saya.

Can anyone comment on the long term effects of
such extereme environemental conditions (hot humid summer/cold dry winter)?

My experience in going back and forth between extremes repeatedly is that most wood products fail rather quickly if they equilibrate (become completely dry or wet) to the climates. Many glues just can't take the multiple deformations, the paint cracks, different types of wood expand and contract differentially, wood shaped by steam lose their form, etc. If you know you are going to be back and forth and you can swing it, I'd consider buying two iaito and keeping one in each place. It might save money in the long run.

Musicians I know are very careful and diligent in how they store their instruments when traveling for all the reasons above. You may want to search the internet on that topic. There should be a lot of information out there on musical instruments and it should be directly applicable to your situation.

[Kuri]

I hadn't considered sweat as the culprit, but you're probably right. The constriction was towards the end of the saya, so it must have been trickling down with each noto.

Thanks for good advice Lewis.