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Recovering Lost Signatures


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I have seen a few posts recently on old swords that people have noted that they may once have had signatures but have been lost to rust over time.  I am wondering if techniques like the ones they use to recover filed off gun serial numbers can be used on swords without causing any damage. (bit of a CSI style question)

 

One particular technology is called electron backscatter diffraction, or EBSD.  (reference Washington Post) https://www.washingtonpost.com/national/health-science/scientists-develop-a-technique-to-find-serial-numbers-that-have-been-filed-off/2015/05/11/45e76fce-d489-11e4-8fce-3941fc548f1c_story.html

 

Would it not be a good thing to see if some particularly old swords once had been signed by their masters.  Has anyone tried anything like this?

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That is a really interesting question Michael . I have a rather fine suriage Shinto blade . Whilst the blade is in great condition parts of the nakago are not . There are a few random strokes from the mei still visible amongst the rust but there isn't enough left to allow you to read it . Like you I had always wondered if the chiselling of the mei would result in any metal displacement which would mean that techniques like those you refer to could be used to determine what the mei once was . I look forward to hearing what others have to say

Ian Brooks

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I have found reference to this regarding the content of blades but not mei per se 

https://www.researchgate.net/publication/50377688_Ancient_and_historic_steel_in_Japan_India_and_Europe_a_non-invasive_comparative_study_using_thermal_neutron_diffraction

 

Surely if they can read the dials of a 2000 year old "clock" Antikythera mechanism;

 they can read a signature ;-)

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In the firearms industry, we can recover serials if filed off, because they are stamped and impressed down into the metal.

It's my understanding that mei are cut, not punched down, so the displacement of the metal is to the side and not down. Therefore not as easy to pull up the mei once removed.

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I have used EBSD when I worked for an aerospace company.  EBSD is not currently practical for swords because the sample must fit into a small vacuum chamber and the sample must also be extremely flat.

 

EBSD is similar to x-ray diffraction except that electrons are used instead of x-rays.  EBSD can determine the crystal orientation of each metal grain on the surface of a specimen.

 

Tom Woodrow

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X-ray also use electrons, so EBSD might really work. Anyone having such a machine at home? :) 

The MEI is hammered in with a chisel, so it is not really cut (removing steel), but the vertical impact on the metal is probably less strong compared with a machine stamp as used on firearms or other mechanical parts.

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EBSD should work if the nakago is just rusted, but if the mei has been forcibly removed (by togi or whatever), then I doubt it would be accurate. But Tom is right that the volume for those machines is pretty darn small, & is likely the limiting factor. Cost is significant, too.

 

Ken

 

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While the chiseling might not be as strong as a stamp, I suspect it's left a mark, not as defined, but its amazing what sofware can do nowadays, especially if there is a database of signatures for it to compare it against.  but it does sound like a bit of effort...i,e, money no matter which way you go, along with the current technological barriers.

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Signatures are not cut but done by chasing and hence are the equivalent of punching. This causes the displaced metal to form the tagane makura on a new / newish signature. Since the metal below each stroke is deformed by the process, it should be possible to detect an erased signature. Mitigating against this is the fact that the area where the signature was will have been covered with coarse file marks and will also be covered with rust. It would however be perfectly possible to use some technique such as neutron spectroscopy - the olny problem there is the cost of each scan.

Ian Bottomley

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I am sure there are those out there that would spend the money on certain blades if it could be shown to be signed by a specific smith especially if the mei was obliterated over time by rust and wear rather than removed by a toshigi. Anyone have one of these pieces of apparatus want to make a cut ?  :)

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At the bottom :-) :

 

F. Salvemini, F. Grazzi, S. Peetermans, F. Civita, R. Franci, S. Hartmann, E. Lehmann, M. Zoppi, Quantitative characterization of Japanese ancient swords through Energy-Resolved Neutron Imaging, Journal of Analytical Atomic Spectrometry 27, 2012, 1347-1354

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  • 2 weeks later...

Very interesting question, and the answer is yes.

 

Ttheoretically both techniques you mentioned could be used for identifying old signatures (the signatures are usually chiseled and during chiselling the material is compressed both vertically and sideways).

 

However, this is not done because it is extremely costly, and unless you have a lost Masamune (figuratively speaking) the cost for reading the signature will exceed by more than ten times the price of the sword.

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At the bottom :-) :

 

F. Salvemini, F. Grazzi, S. Peetermans, F. Civita, R. Franci, S. Hartmann, E. Lehmann, M. Zoppi, Quantitative characterization of Japanese ancient swords through Energy-Resolved Neutron Imaging, Journal of Analytical Atomic Spectrometry 27, 2012, 1347-1354

 

Recommended reading. Wonder if Civita and Franci from Stibbert Museum of Florence belongs to this board...

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