More Science! - Radiocarbon Dating Nihonto?

[Vermithrax16]

A friend of mine had asked me about this 2 weeks or so ago as he has a broken sword that is likely from a VERY early era in the craft. With no real way to do kantei, he wondered if there was a way to date the sword. Then the same type of thing came up on a Nihonto Facebook post. My first thought was no, radiocarbon dating is for organic materials, not things like steel. I know one can certainly date pre-atomic bomb steels (low background steel lacks the radio isotopes that came from testing of bombs; posted about that in the off topic section) but that was it.

 

But.......

 

I did some searching at work (I have access to every scientific journal in existence there) and I found some interesting things. The charcoal used to forge the nihonto was organic. Assuming it was not made 50 plus years earlier than the sword was forged, it seems it may be possible.

 

I am not a metallurgist or a physics guy. I suck at math, so that is what I am a molecular biologist

 

So I submit the following two articles for a read and though example, I have not had the time to really go over them in full detail.

 

Paper 1:

http://www.tms.org/pubs/journals/JOM/0305/Cook-0305.html

 

Paper 2 (better one):

https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/3449/3731

 

[Ken-Hawaii]

I've had the second article for a couple of years, Jeremiah, but the first one is new. Nice find!

 

Ken

 

[Vermithrax16]

I've had the second article for a couple of years, Jeremiah, but the first one is new. Nice find!

 

Ken

There is a Japanese one I am going to translate via our services at my work, it's very new. Interesting thinking fun!

 

Oh, and Happy Birthday if I missed it!

[Peter Bleed]

I hate to be a wet blanket, but... Things like a C14 date are only really useful if they somehow link to specific issues.C14 dates are not free. Suspecting that a junk blade might date to "a VERY early era" doesn't strike me an issue worth throwing money at. WE absolutely KNOW that swords were made in Japan since "a VERY early era" so one more date would not increase out understanding.

Does this broken sword presents some potentiallyinteresting questions that could be addressed. Is it  signed? What suggests it is old.

Just because something can be done - does not mean it is worth doing.

Peter

[Ken-Hawaii]

 

Just because something can be done - does not mean it is worth doing.

Peter, scientists have been doing things like this for years - that's how science advances, one small new technique at a time. For this blade, you're probably right, but I don't think that anyone had thought of extracting ¹⁴C from Nihonto before this experiment. And now we have a new tool.

 

Ken

 

[ROKUJURO]

I am not sure that no one didn't think of applying the C14 method to Japanese blades, but we have to consider that the method is not very precise in relation to 'recent' history (= a few hundred years). You have to calculate plus/minus 30 years in reference to the year 1950. In some cases this might not be precise enough.

[Okiiimo]

The nuances of carbon dating are beyond my expertise, so I ask this question in ignorance. Wouldn't the forging process "reset" or destroy the C12 - C14 ratio - making it impossible to determine the date?

[Ken-Hawaii]

In a word, no. Otherwise, it would be very convenient to burn anything radioactive that contains carbon to get rid of the radioactivity, but it doesn't work that way.

 

Ken

 

[Okiiimo]

Ken - with respect, I wasn't suggesting that forging removes radioactivity or changes the rate of decay. I was suggesting that the forging process may alter the C12 to C14 ratio of the original organic material. Once the ratio is altered, it may not be possible to apply the data to the C14 decay curve to come up with a meaningful date.

[Ken-Hawaii]

I see what you mean, Allan. Adding carbon in the kitae process seems to be pretty much a single point in time via charcoal, hay, etc., & once the carbon isotopes are "integrated," I'm fairly sure that the rest of the forging process isn't going to change the ¹²C/¹⁴C ratio, or at least I can't think of any way that would happen. The carbon in the various tamahagane pieces chosen by the tosho are already "burned-in," too. I just asked my physicist wife (who also swings swords), & her only comment was to remind me that the hammering & folding is intended to drive out impurities, & to somewhat homogenize the carbon atoms in the iron to create steel. Does that help, or just confuse the issue?

 

Ken