Storing blade in Koshirae

[Emil]

I recently gifted my father a Showato in traditional Shirasaya and Koshirae that I bought from Aoi Art along with a kiri bako for ideal storage.

 

He wants to enjoy this sword by storing it in Koshirae on a wall hanger at up to a week at a time.

 

As I've mentioned in another post it already has some tiny rust spots along the blade and I don't want to make it worse, but I do understand his desire to showcase it for a few days occasionally.

 

Any advice on storing a katana sitting in its Koshirae on a wall openly? Should I tell him it's better to just display the Koshirae with the tsunagi? Or is one week at a time in Koshirae fine?

 

I already told him not to put the wall hanger close to the fireplace or windows to save the lacquer from rapid changes in temperature and direct sunlight.

 

Any advice would be highly appreciated 

 

[1kinko]

Oil and low humidity.

[ckaiserca]

I would strongly suggest that he display the koshirae with the tsunagi and keep the blade in its shirasaya. It should be fine to keep it displayed like that indefinitely. 

[ROKUJURO]

A blade should rest in its SHIRA-SAYA, KOSHIRAE will suffer from oxygen and UV rays in the long range. So an air-tight case would be better for the latter in case it was a good one. Sometimes a cheap IAI-TO can be sufficient as decoration.

[Emil]

I agree with you, it's probably a better idea to display an iaito.

 

Just out of curiosity, some Japanese sword shops that I've been to, display their blades in open air all day long, every day.

 

This one for example displays probably a hundred blades outside of both koshirae and shirasya, some of them with a pricetag up to 2.3M JPY.

 

They have a rack of 10-20 Shinsakuto sold only in Koshirae, you don't even get a Shirasaya. And they are also displayed in open air.

 

I was curious to how they manage to maintain all those swords while customers are free to walk around and breathe on them.

 

 

 

 

 

[ROKUJURO]

Emil,

it is probably less wear on the blades to lay them out 'naked' than to un-sheath and re-sheath them a dozen times a day for the customers. This would also damage the KOSHIRAE if not done very carefully.

If the blades are wiped and oiled once a week, they should be fine. 

[Nicolas Maestre]

For what it's worth, I have been practicing iaïdo with a steel blade for almost 15 years, stored of course in its koshirae, and it's absolutely like new... It's always oiled and taken care of since I use it weekly for training though.

 

Also I have read that some folks here do not even oil their blades. I guess it really depends on how bad humidity is in your country/area ? 🤔

 

So I don't really understand why koshirae would be worse than shirasaya? (genuinely asking!)

[ROKUJURO]

1 hour ago, Nicolas Maestre said:

.....So I don't really understand why koshirae would be worse than shirasaya? (genuinely asking!)

It is simply a different use and purpose.

[Emil]

3 hours ago, Nicolas Maestre said:

For what it's worth, I have been practicing iaïdo with a steel blade for almost 15 years

 

What kind of sword do you use what steel is it?

 

I've seen people reference to iai and samurai for this in the past as well. They claim if you use your sword often enough and just wipe it every time after use, it will be fine.

 

Which technically must come down to airing the saya and wiping of any built up moisture from the blade once a week?

[Gerry]

I have been collecting nihonto for over 20 years, and I've always been one to transfer them from their shirosaya to the koshirae once I receive them, and I never keep them oiled either, with no ill effect.

 

Some of my swords have been in their koshirae for over 20 years on my sword rack, unoiled, without developing any rust. And until this year, I lived in a city where the humidity in my house was about 50%.

 

I prefer to keep my swords in their koshirae because I like the feel of how a sword was intended to be handled, in koshirae. And also, I have an unfounded phobia of my hand slipping on the shirosaya handle, and my hand getting cut, so a tsuba is always nice to have. So now I have a huge stack of shirosaya over the years that I really need to get sorted and tagged, ha ha.

 

Maybe it's also because most of my swords are TH and below, and not Juyo or TJ, so I'm not as concerned with keeping them in absolutely pristine condition.

[Benjamin]

Hearing some of you could lead to think that rust doesn't exist anymore... just a problem of our imagination...

That's very lucky of you if a X decade of conservation in koshirae didn't alterate your sword but don't spread your example as it would be reproductive. And again don't use a X decade habit to make conclusion on a X century aim to preserve.

Shirasaya saved blades when their owners couldn't clean them daily or weekly (as warriors did in old time) or oil them twice or three time a year (as collectors do). Because you don't know what will be tomorrow and s**t happening some time in life, some of us could be temporarly not capable to see at our swords regularly. Happily for posterity most of us have the habit to conserve them in shirasaya.

[Gerry]

I guess I must be lucky then...but just to point out that nihonto are instruments of warfare, and weren't originally designed to be babied.

[Robert S]

I also don't understand the difference in storage conditions for the nihonto between koshirae and shirasaya.  If the issue is potential wear on really high quality koshirae, that I understand, but most of the koshirae that I see are not at that level.

[Schneeds]

The shirasaya is designed to have a much better seal, and therefore moisture barrier. 

[Ghoul]

From the perspective of just rust I think as others have said it would be safer for the sword to be kept in the shirasaya.

 

However if by being in koshirae and on display it would mean it was more enjoyable for people, and that in turn means it is cared for and not forgotten about (where it could then be mistreated down the road due to lack of appreciation), I'd personally say this particular risk is probably worthwhile.

 

If anything, changing it from shirasaya to koshirae once a week is much riskier than just leaving it in either one - there's a chance of dropping, scratching, or leaving fingerprints each time this is done, so I'd probably just stick with one and only change if needed when doing required maintenance. Maybe then use the shirasaya if going on holiday etc..

 

As an aside, you're lucky to have both options! All but one of my swords only have koshirae - in the UK at least it seems rather rare to find blades with both.

[SteveM]

17 hours ago, Schneeds said:

The shirasaya is designed to have a much better seal, and therefore moisture barrier.

 

I think it has more to do with the effect of the lacquer on the wood of a koshirae, rather than the fit of the koiguchi.

 

By this I mean the wood of a shirasaya is a somewhat permeable/breathable material that allows for any residual moisture inside to escape outside the shirasaya, whereas the lacquer on a koshirae is an impermeable membrane, trapping moisture inside the saya and causing the blade to rust over the long term. This is the general belief, anyway. I don't know if there have been any scientific studies done to quantify this.

 

(There might be some 2nd tier effect of repeated sheathing and unsheathing of the sword from the koshirae, causing the koiguchi to become loose, but it should never be so loose that the sword is rattling around inside the koiguchi). 

 

18 hours ago, Gerry said:

but just to point out that nihonto are instruments of warfare, and weren't originally designed to be babied.

 

Hmmm. I'd say nihonto were the crucial tools of a certain class of people, and if they didn't baby those tools, the tools would quickly rust, and would cease to serve their function. I think babying nihonto is a tradition that is as old as the craft of swordmaking itself. Otherwise, there would be no beautiful old swords left today.  

[Schneeds]

29 minutes ago, SteveM said:

 

I think it has more to do with the effect of the lacquer on the wood of a koshirae, rather than the fit of the koiguchi.

 

By this I mean the wood of a shirasaya is a somewhat permeable/breathable material that allows for any residual moisture inside to escape outside the shirasaya, whereas the lacquer on a koshirae is an impermeable membrane, trapping moisture inside the saya and causing the blade to rust over the long term. This is the general belief, anyway. I don't know if there have been any scientific studies done to quantify this.

 

That's interesting, like a wicking effect?  It probably works to soak any current moisture off the blade and keep new air from circulating in. 

[Emil]

This is the same explanation as I got to why kiri bako are used to store swords.

 

When the air is dry, the wood release its moisture and when the air is humid, it absorbs moisture. This way, it's creating a more stable climate for the blade and Koshirae stored inside the box.

 

On top of that, paulownia wood used for kiri bako have the additional benefit of natural pest reppellants and having one of the most thermally insulating properties of all woods. These additional benefits are not necessarily same for shirasaya, as it is made of Japanese magnolia.

[Gerry]

Now I thoroughly curious...are there any members out there who can share their experience with leaving their swords in koshirae, oiled or unoiled, only to find them rusted upon the next inspection of the sword?

 

If rust was found, how long was the interval between inspections for the rust to develop, and how severe was the rust?

 

It's good to have factual data points on this matter for the thread originator, rather than just hearsay or theories.

[Shugyosha]

Gerry, 

It’s going to depend on the climate where the swords are kept.

 

I never once had an issue with rust on my blades and I only oiled them for transport. In my own home they were kept unoiled and rubbed down with a microfibre cloth after viewing (no uchiko). They were each stored in shirasaya with a sword bag, and all in a paulownia chest which was kept in a room with no radiator.
 

This is in the UK midlands - more humid climates and closer to the sea might get different results. 

[Matt D]

I’m interested in answers to Gerry’s question. Many of the shinkasuto don’t come with shirasaya.

[Shugyosha]

You do an experiment with carbon steel stock where you are an you’ll have an answer of sorts. 

[Alex A]

I wouldn't store a sword in its original old antique koshirae, not if its a valuable blade in good polish.

 

Would be concerned of crud and old oil, oil that promotes rust (as been said a dozen times)

 

 

[Matt D]

But what about koshirai of a shisakuto that was made in the last 40 years? The blade is in reasonable polish but has some saya wear. I have no plans to train with it but I would like to preserve it

[Gerry]

1 hour ago, Shugyosha said:

Gerry, 

It’s going to depend on the climate where the swords are kept.

 

I never once had an issue with rust on my blades and I only oiled them for transport. In my own home they were kept unoiled and rubbed down with a microfibre cloth after viewing (no uchiko). They were each stored in shirasaya with a sword bag, and all in a paulownia chest which was kept in a room with no radiator.
 

This is in the UK midlands - more humid climates and closer to the sea might get different results. 

John, you make an excellent point on the local climate.

 

I wouldn't do what I do if I lived in the tropics, or lived close to the ocean. And I keep my house air conditioned 24/7, and don't have my windows often very often.

[Robert S]

As a reference. I keep my blade in koshirae, and live in a temperate climate within 1 km of the ocean, but in a house which is heated during the winter.  I also inspect my blade and give it a basic wipedown at least weekly, and oil it at least once a month.  No rust at all, so far.