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Steve D

Caring for a rusty Katana

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Just thought I'd add a few more pictures to this. Had a good look over the blade and, hopefully, there's more surface rust than pits for the majority of it (not that I have a trained eye of course). 

What are your thoughts? 

It certainly 'feels' like surface rust if I scrape my nail along it..

 

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When a drop of water hits an iron object, two things begin to happen almost immediately. First, the water, a good electrolyte, combines with carbon dioxide in the air to form a weak carbonic acid, an even better electrolyte. As the acid is formed and the iron dissolved, some of the water will begin to break down into its component pieces -- hydrogen and oxygen. The free oxygen and dissolved iron bond into iron oxide, in the process freeing electrons. The electrons liberated from the anode portion of the iron flow to the cathode, which may be a piece of a metal less electrically reactive than iron, or another point on the piece of iron itself.

 

So what you see as rust is not an amorphous growth it's the steel surface in essence flaking away at different rates depending on the ease of above chemical reaction.

still with the removal of enough steel and hopefully no pitting you will get a decent finish . But invisible flaws is another matter altogether.

In many people's minds it's worth the polish but then they are not paying for it.

this is betting on the favourite at the Horse races at 2:30 at Newmarket.He should win,he could win... but he might not win.

Steve go in with a level head and eyes wide open here. Save up £3000?? for the Japanese polish.

Good luck and I mean that.

Adam

 

 

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Evaporust. Keeping the nakago OUT of the solution. I know some will be horrified at the thought of a chemical, but I've been playing with the stuff for a while on other steel recently and it is pretty remarkable and doesn't affect the underlying steel. Max 6 hours. Maybe suspended in a vertical tube.
 

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2 hours ago, Brian said:

Evaporust. Keeping the nakago OUT of the solution. I know some will be horrified at the thought of a chemical, but I've been playing with the stuff for a while on other steel recently and it is pretty remarkable and doesn't affect the underlying steel. Max 6 hours. Maybe suspended in a vertical tube.
 

Might try in on the old French sword 1st...

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Steve,

Good start on the measurements.  A biggie is "sori".  Check this site on how to measure it: http://japaneseswordindex.com/measure.htm

 

You'll eventually need to remove the habaki.  Rust can make that more difficult to do.  I use a hard plastic, like the edge of a spatula or something similar, against the front edges of the habaki, then tap it with a hammer.  It will break the rust-lock without scratching the blade or damaging the habaki.

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Glad you've caught the nihonto bug! Or well, at least with respect towards your family's heirloom! Its good we have another person hanging about here.

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36 minutes ago, Bruce Pennington said:

Steve,

Good start on the measurements.  A biggie is "sori".  Check this site on how to measure it: http://japaneseswordindex.com/measure.htm

 

You'll eventually need to remove the habaki.  Rust can make that more difficult to do.  I use a hard plastic, like the edge of a spatula or something similar, against the front edges of the habaki, then tap it with a hammer.  It will break the rust-lock without scratching the blade or damaging the habaki.

Thanks Bruce.

Habaki removed (quite easily with wood & gentle hammer). Maximum Sori is approx 11.25mm, (3.6sun?) (measured with a digital vernier on a CNC machine bed) at approx 360mm from the tip. Roughly the centrepoint between the tip and mune(?)

That would make it a torii sori? 

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26 minutes ago, Steve D said:

Roughly the centrepoint between the tip and mune(?)

You're learning fast! Ha!  That notch is the mune machi (mune meaning back edge).  "machi" is the notch; one on either side.  "Ha-machi is on the cutting edge side.

 

And yes, likely torii sori.  To the eye, it looks koshi sori, but that is an illusion due to the blade tip being narrow and the end near the machi being wider.  But now, I'm speaking WAY out of my area of experience!

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1 minute ago, ChrisW said:

How wide is the blade at the yokote line? (from side to side)

Approx. 17.3mm although it's a fairly smooth curve rather than a sharp line. 

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1 minute ago, ChrisW said:

I meant thickness. Sorry, I suppose I could have worded that better! 😆

Yeah, wasn't sure that would be what you meant 😆

It's 4.2mm 

 

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One thing that can be said about polishing by an experienced polisher is that the sword will always end up looking better, even if it is not possible to be perfect due to structural flaws. The Japanese saying was something to the effect of....better to wear away than rust away.

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12 hours ago, Brian said:

Evaporust. Keeping the nakago OUT of the solution. I know some will be horrified at the thought of a chemical, but I've been playing with the stuff for a while on other steel recently and it is pretty remarkable and doesn't affect the underlying steel. Max 6 hours. Maybe suspended in a vertical tube.
 

hi brian, may i ask what are the results of using this solution on rust?  i have used it on rusted axes and found it great at removing the rust.  but the metal is left with a dull grayness afterwards and im not sure if that is a new layer of oxidation or just residue from the chemical.  i also found that if the treated metal is not then treated with oil within the week a new layer of red rust will very quickly develop if there is sufficient moisture in the air.  what is your experience with that chemical?

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This isn’t a recommendation to use it on Nihonto. So please don’t go throwing your 80% in-polish swords into it. But for a blade like this that is total rust scale, it will be a big improvement. I have used it on various antique knives and have been impressed. It does not affect the steel. Only the rust. I leave it in for a half hour, followed by brushing with a brass brush. Then in the solution for a few more hours. Not longer than that. I wash it off with water and repeatedly use oil, as it will form rust if left untreated. It is not an acid, base or solvent. It WILL remove bluing and patina from guns and bayonets. Don’t ask how I know. 
So only for bare steel. It will leave cast iron a bit dull but haven’t seen that on steel. 
Not for tsuba!

 

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Like Brian, I have used Evaporust on knives & other iron/steel items, with excellent results. I've never tried it on Nihonto, but see no reason why it wouldn't work.

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Darcy has come back to me and believes the blade could be around 600 years old and should be worth investigating more.

Has put me in touch with Ted Tenold with regard to getting a window polish done to determine school and maker.

"Right now it's a lottery ticket, and we can help reveal if it is a winner."

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That is fantastic news. Darcy and Ted together make an awesome team and won’t steer you wrong. Please keep us updated. 

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This is an interesting one, the sword is Kaku-mune, this type of mune is rigid and found on very old swords, older than 600 years, more like Heian period. At first i thought Muromachi but the sword has a raised shinogi, slender in shape and tapers too much toward and extended kissaki for that. The kaku mune is also very important. Seeing as the rust is uniform perhaps the sword has not been reshaped or badly altered with a grinder as many have been in the past. You might (hard to say without a clean polish) even have an old old gem here or something trying to be if it was re-profiled at some point in its life. Good luck with this one and i hope it is a heian piece!

 

About the habaki...not sure at all, never seen that

 

Any chance of more pictures of the mune, especially under the habaki leading up to the kissaki? Sorry for all the asks

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"...the sword is kaku mune,".

 

No it's not, according to the drawing that Steve did for us.  Easy to think so from the pictures but.....

 

All the best.

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It's not a kaku-mune unfortunately, it's lori-mune as far as I can tell.

I'll add some more pictures tomorrow as I'm away from the sword today.

 

 

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