NBTHK and uchiko

[Jacques D.]

I'm lucky enough to know a very good Japanese polisher who taught me one thing: the less you touch a blade, the better you preserve it. I cleaned my swords when i bought them and they had never been oiled since. It's useless in a room where the average humidity is 45%.

 

Now, you can do what you like with what I say, that's not my problem.

[Brano]

I totally agree with you that with the climate of inland Europe there is no need to oil the blades if you check them regularly

 

[Matsunoki]

33 minutes ago, Jacques D. said:

It's useless in a room where the average humidity is 45%.

How about when humidity is 70%+ eg Japan and many other locations?

Also how about answering my question…..if it is to be avoided why do the Japanese continue to use it….if it is “no longer an option”? (In your opinion?)

[Bugyotsuji]

Humidity 95% yesterday in my area of Japan.

 

Now… 4:15 am

 

[Jacques D.]

Dew point at 25° is fairly high  i calculated it at home, it is  7.7°

 

ps sry for being off topic.

 

ps2 Colin you don't have to address me, I won't answer you.

[Rivkin]

Good test is to have sterling silver cup or something at home. If within couple of months it turns dark grey you definitely need to oil the blades.

The issue is very often not the humidity itself but either seasolt or sulfur (power plants) which are exceptionally corrosion-friendly.

[Brian]

I'm still largely with Darcy in my opinion of not needing to use uchiko. I stated the above to show that proper use very occasionally shouldn't damage swords if done properly and with high grade uchiko. But for the average person, on polished swords, just use the isopropyl alcohol and microfiber cloth method, and a very light oiling. And as seldom as possible.
I use uchiko on project blades totally out of polish, that barely show a hamon and are completely stained. The red and black stuff that comes off is incredible. Over months and years, the hamon will appear and rust will stabilize. Oiling is also vital. But stick to these out of polish blades. If it reduces the temptation to grab something more abrasive, then win win. So with uchiko, generally just don't use it on polished swords.

[Brano]

9 hours ago, Jacques D. said:

Dew point at 25° is fairly high  i calculated it at home, it is  7.7°

 

ps sry for being off topic.

 

ps2 Colin you don't have to address me, I won't answer you.

If you have a relative humidity of 45% at a room temperature of 25°C, then the dew point is about 12.3°C, but it is not very important
The storage space (cabinet/ safe) has insulating properties and so does the shirasaya, so the temperature of the blade does not drop quickly

 

[Jacques D.]

21° at home, thank you my old stone house with 70 cm thick walls

[Brano]

For 21°C and 40% it is fine
The storage/insulation ability of old buildings is priceless

[Bugyotsuji]

Off topic once more so apologies, but I heard that an Osafune polisher is selling the finest home-made uchiko powder you can imagine; he had been developing it for quite a long time, I hear. I was tempted to buy some in the Osafune Sword Museum shop, but it wasn't cheap!

 

And many years ago in early summer I visited the descendants of the Karo of Ise Kameyama Castle, who had inherited the storehouses and the keys to them. They said they had some lovely swords but were unwilling to bring them down and show them to me. "This is the wrong time of year to remove them from their shirasaya", the father explained.

 

[Franco D]

29 minutes ago, Bugyotsuji said:

I heard that an Osafune polisher is selling the finest home-made uchiko powder you can imagine

 

Bob Benson said that when he made his uchiko it was screened and sifted seven times to ensure its quality and fineness.  

 

Additionally, if you want to see whether or not there are hike from uchiko on a sword view it under a quartz halogen lamp. 

Which you may want to use for sword study regardless as quartz halogen lightening shows off the good, the bad, and the ugly.