How to remove green corrosion?

[Yumso]

Hello, everyone.

 

I've got interested in this hobby like 2 months ago, and started buying things.

It was my first time buying koshirare(cheap one!) with tosogu that followed with it, and got items this wednesday. Was super happy seeing it.

 

But I have one problem now : it has too much greenish corrosion and I don't know how to remove it!

I've oiled them with tsubaki oil for now, but I do want to get rid of these.

 

Does anyone have an idea to remove these? Should I try putting them in vineger for a while and rub it with toothbrush? 

 

Thanks,

Yoon

[Franco]

1 hour ago, Yumso said:

Should I try putting them in vineger for a while and rub it with toothbrush?

 

No!  Vinegar is acidic and that should definitely not be used.

 

1 hour ago, Yumso said:

Does anyone have an idea to remove these?

 

Because these are mounted fittings I would consult with a professional first before attempting to clean these.  Loose fittings are a different story.

 

Regards

 

[ROKUJURO]

Yoon,

welcome to the NMB forum!

Oiling is the wrong way, too! 'Green corrosion' can occur on copper-alloyed metals as a result of a chemical reaction with fatty substances. As Franco said, you will probably damage the TOSOGU with chemical treatments, so go slow in this case! You do not want to damage the patina, which is important.   

I would recommend a careful cleaning with a toothbrush and a clean cotton rag right now.  

Cheap KOSHIRAE usually need a lot of competent work to restore them which is why they are not expensive.

[Brian]

One drop of oil and a soft toothbrush. Or even isopropyl alcohol and a toothbrush. Wipe with the aforementioned soft cotton cloth.

[Yumso]

Thanks for the reply&advice everyone.

I'll not try vinegar.

 

So basically repeating "small amount of oil use(or maybe not using is the best?) -> gentle brushing -> wipe with paper towel" until I get rid of green right?

Under images are what they look like right now after some oiling & toothbrushing.

 

Thanks,

Yoon

[Franco]

3 hours ago, Yumso said:

So basically repeating "small amount of oil use(or maybe not using is the best?) -> gentle brushing -> wipe with paper towel" until I get rid of green right?

Under images are what they look like right now after some oiling & toothbrushing.

 

The problem here is oiling and toothbrushing while possibly removing some of the verdigris may not solve the problem nor achieve the result desired. 

 

The kashira shows signs (at least to me) of having been exposed and damaged by something chemically corrosive. It needs more attention than simple cleaning, like professional help. The shitadome on the kashira look embedded with verdigris. Proper cleaning will require removing them for cleaning. Unless all of the green is removed and properly treated there will be a good chance that over time it will come back. Getting oil and/or water on and soaked into the ito during the cleaning process may only make the problems become worse. While the fuchi/kashira may be Nara school fittings, the damaged kashira may bring the effort to save them into question. 

Since the fuchi is apart it can be cleaned. I would begin by using a soft wooden toothpick to very gently scrape and loosen the verdigris. Then, using a soft cotton Q-tip dipped in anti-hydrous isopropyl alcohol wipe away the loosened verdigris. Repeat that process until gone. The, once you're convinced the surface is clean, again, using a soft tipped Q-tip apply a thin film of good neutral light sword oil. It is always wise to do a test spot somewhere inconspicuous to be sure what you're applying is safe and is not doing any harm.

 

p.s. change soiled Q-tips, do not reuse once soiled.

 

On a personal note, it looks to me as if this entire tsuka and wrap needs to be redone.

 

Regards

 

 

[Bazza]

The kashira appears to portray Europeans - Dutch??  So then, is it early Edo??

 

BaZZa.

 

PS: Agree with Franco that the whole tsuka needs a complete restore by a professional.  Maybe not economical, but it would look much, much better.  How far to go is the question.  Yoon, what is the blade like??

Edited April 28, 2024 by Bazza
Add PS.

[Yumso]

Franco,

 

You are right.

I think I may have cleaned fuchi well, but on the other hand kashira is now... 

Seems like I've rubbed out bit too much. I think I'll just stop here and just oil it frequently to try my best NOT to rust it again.

Maybe I should take them to show professional when I go to Japan.

So... yeah. Learned my lesson in a hard way. 

 

 

Bazza,

 

Just bought koshirae, no blade was included! But yes, seller did mention it was made in Edo period. Not sure about the exact year.

 

 

Yoon

[ROKUJURO]

4 hours ago, Yumso said:

.....I think I'll just stop here and just oil it frequently to try my best NOT to rust it again.....

Yoon,

these are soft metal TOSOGU which will not rust. Rust only occurs on iron/steel. Nobody wants to oil their TOSOGU, so please do not do that.

Concerning the chemistry of "oils": there are natural oils which are composed of fatty acids. These can react with copper alloys. So-called 'sword oil' will mostly be mineral oil (made from crude oil). These are composed of low-viscosity paraffines which do not react with copper.

Keeping your TOSOGU clean and dry will be all that is necessary.

[Yumso]

Jean,

 

Got it. Thanks alot!

 

 

Yoon

[Franco]

8 hours ago, ROKUJURO said:

Nobody wants to oil their TOSOGU, so please do not do that.

 

For clarification/explanation, my bad. Yes, you are not oiling your fittings. Sword oil is used during the process of arresting the verdigris. 

In the end, when satisfied that the verdigris is completely gone and not coming back, I clean the final surface with the alcohol. 

 

Regards

 

[ckaiserca]

The motif of the Kashira is interesting. It appears to be an Asian man and a European man. The European man looks like he has a clown's nose.

[Franco]

22 hours ago, Yumso said:

Maybe I should take them to show professional when I go to Japan.

 

As with nihonto the cost of restoration vs value becomes a factor in restoring fittings. 

 

Regards

[Winchester]

Hi Yoon,

 

Thanks for your post and welcome to our shared hobby--enjoy! 

 

In my opinion, you have done enough now and can just enjoy these, while keeping an eye on them periodically.

 

It has sentimental value to you and you will in time collect and learn more. "Enjoy the ride".