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Metal detector and Nihonto


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Hello all. I hope everyone is doing ok over the last couple years haha...

 

So, as the title says, I was testing my Nihonto with my metal detector out in the open(several in Shirasaya on bed) and one of them, and older one, keeps coming up positive (or same tone anyways) as precious metal.

 

Anyone know about this? High copper content? Every other sword reads with a different tone but my oldest hits for precious metal. Weird. 

 

It is a Mino/Nao Shizu looking blue steel if that helps

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5 minutes ago, PNSSHOGUN said:

Depending on the location of the where the iron sand was sourced it will have trace elements of all sorts of metals. I know Titanium is one.

 

Interesting. I need to find some titanium to test. As of now I have tested a sterling silver zippo lighter, sterling silver ring, a .9999% Austrian Silver coin, 14kt to 24kt gold, .9999 Palladium coin and they all make the same ping as the sword

 

But then smaller sterling silver items like necklaces make a totally different noise so I dont know if its by density or shape or what. All my other swords make the same sound as sterling silver necklaces or lesser (well not "precious" and def not lesser in my eyes) metals.

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AHi all. My Minelab GPX5000 will sound off on any metal with a very similar tone. There is no real effective discrimination on the 5000. My Garrett GT2500 will sound off like precious metals on larger pieces of steel, ie horse shoes, sheet iron etc. The larger pieces of iron overload the discrimination circuitry of the coin machines and they get confused. Smaller pieces of steel/iron don’t show up on the GT2500.

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Dwain,

there is no (or almost no: < 0,001%) copper in Japanese blades. Copper is detrimental to steel, and the Japanese iron ore (SATETSU) only contains very small amounts of it. The same applies to titanium, so there is no way to detect these impurities in an alloy. 
 

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Please, what detector are you using?  On certain settings iron will give you a false reading. You mentioned "on the bed" Are these on a neutral surface when you scan and not upon bed springs? (a round spring will give a false reading also)   

 

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X-ray fluorescence equipment could tell you what alloy composition you have without damage to the blade. Some of the larger salvage yards have that equipment and can be talked into running a quick test. It just takes a minute and provides accurate alloy composition in percents. I would be interested in any such data on Japanese blades that anyone in the group gathers. It would be interesting to create a database of alloy composition by schools, smiths, and periods. If I ever win the lottery I might spend the $50 K for the equipment and bring it to a show.

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14 hours ago, Brian said:

Gotta know what you are holding there and the story.

Brian,

      27 ounces at 15 inches worth about AU$80,000. My other passion !

Chris

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Awesome! Thanks for the responses everyone! Lots of great info! 

 

Yeah I don't know why I said copper. Maybe I was thinking about carbon? I dunno Haha

 

The testing was done in multiple places. First I used the bed and other things were scanned too. Jewelry, .9999 silver coins,  gold bullion, regular coins,  etc...  all a couple feet apart. They all made different sounds and in the spaces between nothing registered so I don't think any springs interfered because I also tested on the floor (I put a sheet down and sword pillow) as well as on the wall hanging in the swords display

 

The older sword makes the same high pitched sound/beep/tone as .9999 silver Austrian coin,  a sterling silver Zippo case,  sterling silver ring,  24kt bullion.  The "newer " sword makes the same sound as regular pocket coins,  plated brass bracelets, steel, etc... The older sword could be as old as 1400s but it's definitely koto. Newer sword kantei points possibly to early/mid 1600s 

 

The metal detector model is just a regular Big 5 type. It's not cheap by any means but it's not high end. I think it's called "Bounty Hunter Tracker IV"

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The discrimination circuit in most sub-$1000 metal detectors aren't very good at identifying anything except base metals (iron, tin, etc.). The good ones will also indicate silver/gold/platinum, but unless you have X-ray fluorescence equipment, don't expect to see any differentiation.

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