Copper Penny For Rust On Nihonto?

[Death-Ace]

Has anyone ever used a pure copper penny to effect on an out of polish blade or one in polish? Also, any damage (ie, scratches) noted?

 

I used one to great effect on my gimei and also attempted it on a Nagatsugu O-Wakizashi in an old poor wartime polish. Only ussd it on the light fingerprint rust on two areas with one near the ha. Could've have sworn it burred the blade but was away from the rust so may be my imagination, I hope!

[Ken-Hawaii]

Normally, something relatively-soft like an antler is used to clean active rust. Never heard of a penny being used.

 

Ken

 

[Stephen]

we had old post on it, reportedly working, basically like a burnish rod. 

[ROKUJURO]

Yes, that works, but is has not necessarily to be a penny. Any piece of soft metal may be used to scrape the active red rust away, but this procedure does of course not replace a polish, and it is not a means of restoration.

Attention: Some soft metals may catch on very coarse parts of a rusty item and leave traces! This is not a problem if these metals themselves do not corrode easily.
In my experience, the old recommendation (see above by Ken) to use ivory, bone, antler or similar is a good one. 
    

[seattle1]

Hello:

 It is an old practice to use a high copper content penny, the safe ones being pre-Elizabeth II, versions that feature British monarchs from Queen Victoria to the current Elizabeth, her early years of her reign having high copper content, but safest to avoid. Used on superficial rust spots they should not damage the adjacent polished area at all or even leave a mark, but don't go beyond the boundary of the rust spot anymore than necessary. Never use a current US penny as they are zinc and will scratch. If you don't believe the foregoing experiment on a junker. Seeing is believing.

 Arnold F.

[Baka Gaijin]

Be careful for current  UK coins as they are steel under the copper alloy 

[Death-Ace]

Thanks for the comments, guys! I bought an old worn out 1832 Coronet Cent to use since it is pure copper last year for the other blade. Funny enough, none of these antique stores here had antler or an ivory pick or even old piano keys, so I attempted this. Donte think I scratched the polish of the wak since there are light scratches and a few burrs from the previous owners so it probably me being overly cautious. I'll stick with choji/Rem oil and maybe one or two uchiko treatments and if it doesn't work, I'll keep enjoying as is.

 

Arnold, it was actually your old post that got me started on it and it worked wonders on the Nobuhide so much appreciated!

[seattle1]

Thanks "Death-Ace":

 I used to give out those old good English coins at shows to unbelieving folks for nothing and they would often return with happy praise of the results. Of course everyone should try only on something where damage doesn't matter in any meaningful sense. One sees so many blades with a rust spot or two that someone has scratched away at with a knife blade or dental tool, which always leads to significant damage to a polished surrounding area. In any coin store, usually in a 25 cents "your choice" pail you can pick up such coins, 50 cents at the most. The process is not (!) meant to clean up a generally rusted blade as for that you need a professional polisher for sure; it is only for a few superficial, ie, above the surface, spots here and there.

 Regards,

 Arnold F.

[Darcy]

A penny is not a good idea because it's been stamped.

 

You can take gold which is soft enough to bite into with your teeth, and then hit it enough with a hammer, it will become hard enough that you can put an edge on it and cut someone with it. Not a great weapon, but you could still make a knife from it.

 

Stamping a penny hardens it considerably. If you want to use said penny put a blowtorch on it and heat it until it glows and let it cool off on its own. It will be a lot softer afterwards. 

 

Better would be to head to an art supply store and buy some copper sheeting which will be very soft. 

 

But I think it's a bad idea anyway. All you need to do is to dislodge one piece of gunk of some sort and drag it down the blade to give yourself a nice gouge.  

[seattle1]

Hello:

 I promise (!?) that this is my last post on the benefits of a limited use of a British copper penny (to be safe one with the image of Queen Victoria, which can be bought for a few cents),  carefully manipulated, pre-tested, it being no substitute for a professional polish by a skilled togi-shi,  to remove a few specks of rust that stands proud on an otherwise polished Japanese sword blade.

 Darcy's reference to "not a good idea" and "a bad idea" reminds me of a famous ditty sung by George Schultz, former Dean of the Business School at the University of Chicago and former US Secretary of State, to the retired Nobel Laureate, Milton Friedman, a few years ago at a banquet for the latter: "A fact without a theory is like a ship without a sail...but if there's one thing worse in this universe, its a theory without a fact."

 A copper penny used on a sword to remove superficial rust spots might seem like a bad idea; an experiment on an otherwise ruined sword with such spots would show a surprising result if that rust is surrounded with the reasonable residual of a properly polished surface. The surrounding area will not be scratched up. I have collected swords for some years and have seen hundreds and hundreds of examples of some well intentioned use of a dental tool, a pocket knife, a nail, coarse steel wool, you name it, to remove a bit of rust. The resultant scratches are ugly, distracting and demanding of a professional polish. A copper penny, one that is almost entirely copper, will not make that spot seem to go away, but it will not leave adjacent scratch marks and the rust spot reduced in elevation and less distracting. Needless to say there is no need or call for extending the use of the penny beyond the rust spot. A polish may still be called for, but in the interim the blade will be easier to enjoy. Don't take my word for it; test it first, connect theory and fact.

Arnold F.

[Darcy]

 I have collected swords for some years and have seen hundreds and hundreds of examples of some well intentioned use of a dental tool, a pocket knife, a nail, coarse steel wool, you name it, to remove a bit of rust. The resultant scratches are ugly, distracting and demanding of a professional polish. A copper penny, one that is almost entirely copper, will not make that spot seem to go away, but it will not leave adjacent scratch marks and the rust spot reduced in elevation and less distracting.

 

My apologies to Milton Friedman and his Nobel prize in the art of economics. But it's neither here nor there. It's in fact a bit ironic to use an economist to paint an issue as black or white as famously, if this was a clear science and solved problem we wouldn't have an economic crisis every 8 years or so. 

 

Anyway specific to swords, you cited two examples of material with lower Mohs hardness than a steel blade causing scratches in the steel blade. According to science this is not possible. Then you champion a third lower hardness material saying it is not possible to scratch with it. This anecdotal evidence stands as contradictory to the previous examples. They cannot all be true at the same time, so we mathematicians say (though maybe economists may differ). 

 

Nails and steel wool are softer than blade steel. 

 

I first thought you meant fingernails but simple nails are also in the same boat though not as dramatically.

 

One of the problems though that makes this more complicated than simple surface analysis in regards to relative hardness is that these are average numbers for materials over which there is dramatic practical differences. "Copper" is not just a "3" ... any more than steel has one number. Working any metal will make it harder so you get some differences. Moh's is an estimate and an average at best.

 

There are old glass countertops in stores which are whitened to a complete lack of transparency by the passage of coins over the years. There are questions about how this can happen... they include: contamination of the surface by silicates, contamination of the coins, dropping of the coins causing chipping or differential hardness of a surface material based on the direction you're moving and the grain of the surface.

 

In the case of diamond for instance, the "hardest" material (some material may be harder but don't want to digress) there is no practical way of polishing a diamond surface because there is no material that can scratch it. However when you orient a diamond in different directions you get different scratch resistances. The solution to polishing a diamond surface then is to orient the diamond in its weakest direction of resistance to scratching and then use a diamond dust impregnated steel wheel. The dust crystals have random orientation so on average will be softer than the most resistant direction on the diamond surface but harder than the least resistant. So spinning the iron wheel with the impregnated dust polishes the surface of the hardest most scratch resistant material known to man.

 

If it sounds similar to a copper coin (steel wheel) with contamination (diamond dust) rubbing a sword blade (diamond) you can see where I get "uh, bad idea" from.

 

Testing on a polished sword is also not the same as testing on a dead rustbucket as you can't observe damage to a rustbucket: anything you do to it will visibly improve its state. A perfect polished blade, anything you do to it will damage the state... at best you can hope for status quo.

 

If the results don't matter much and the sword is of no consequence, dip it in acid, rub it on your butt, get your cat to puke up some hairballs on it. The results don't matter so go ahead. But if the sword is in otherwise good condition, don't grab random coins and start rubbing and assume that the results will be good because one collector had a good experience a couple of times though his own commentary is not internally consistent on the matter.

 

It's just in the bad idea zone.

 

Will bad things happen every time? No.

 

Anecdotal internally inconsistent evidence answers all questions in this area? No.

 

Is it a good idea? Not if you care about the results. 

 

Anecdotally I can also be shot by a gun and survive just fine. A lot of people survive gunshot wounds. Don't get shot in the heart or the head or a major artery and probably you will be OK with a bullet or two. Nobody died from a shot in the bicep. This doesn't make it a good idea to get shot. 

 

What I would like to avoid is a bunch of people running out and rubbing any defect they see on their sword with a copper coin pulled from their pocket because they read it's a good idea to do so on the NMB. Because it worked a couple of times for one person.

 

When I think of people rubbing coins against swords I think about all of the damaged glass countertops I have seen over the years (not many but enough to remember them) and it just ends up for me in the drawer of do-it-yourselfer stuff. Choose to do so at your own peril and certainly don't do it on anything of consequence.

 

If you have a rust spot on a good sword, just send it to a polisher and let him fix it. 

 

Again, all respect to Milton Friedman and whatever his nobel prize has to do with swords, but don't rub coins on a good sword please.

[seattle1]

Hello:

 My goodness what an overblown response to the rather straight forward suggestion that someone might want to actually try an empirical test on an otherwise valueless blade which still retains some polished surface, thereby seeing if it is a really such a "bad idea" to use a copper coin (one carefully specified by me and not just one "pulled from (a) pocket"). The mention of Schultz and Friedman was not intentioned to provoke some sort of ad hominum attack on either one, but merely to point out the chops of the person suggesting to Friedman that theory alone is not sufficient, and that was expressed by someone who is not unappreciative of trial and error to another who would agree fully.

 Beyond that the ramble of the post above seems dangerously strange by implication by several assertions made in it. If folks can substitute a steel nail, Mohs 4-4.5, for a correct copper coin, and not expect to scratch the adjacent polished surface, it would be more than surprising. As for steel wool, haven't we all seen many blades badly abraded from steel wool? The comments about economics are just silly and don't deserve a response, unless one believes economists cause recessions.

 Arnold F.

[Stephen]

nothing like a "Darcy" blowing it out of proportion. Ive used the chrome edge of a knife (like a burnish tool) on a out of polished blade that need active rust stopped, Really has got out of hand dont you think?

Willy Shakespeare would be proud 

[Brian]

C'mon guys...I'd rather have too much info thrown out than too little. Let's take it all in the spirit it is intended from all sides, and be thankful we do have access to this type of information.
I think we all agree.....none of these methods on top quality swords that is in reasonable polish. Let's not go further down this rabbit hole?

[Nihonto Chicken]

Rust on steel always results in pits, even the translucent white frost that is often the start of something more serious, though those pits may be too small to be seen with the unaided eye.  Assuming we're talking about the more serious rust, black, red or brown, it is unlikely that a soft copper coin will scratch an adjacent, still nicely polished area deeper than the offending rust spot with underlying pit being addressed.  Since the next polish will need to go as deep as the rust pit, the adjacent scratches, if any, will be taken out as well, so no harm, no foul. 

 

BTW, even with a dead soft copper coin (or anything else of similar nature), scratching of the adjacent polished steel may well occur, not done by the coin or other instrument used itself, but by bits of breakaway rust being pushed away from the offending spot.  My rec, if the blade is in generally good polish, send it off to a professional to remove the offending rust.  If not in good polish, employ the power uchiko method.  Okay, Nomex fire suit donned!