Radiocarbon dating of steel

[John A Stuart]

I finally found the article that supports this method of dating steel. About a year ago someone had asked if it was possible to date the steel used to manufacture Nihonto and I had replied that radiocarbon dating may be used. Of course this raised some eyebrows to say the least. Here is a section (that which deals with Japanese produce) of that report of the radiographic analysis of steel. Coal or coke are not able to be dated if used, coal as it is a fossil and coke because the Carbon 14 is depleted, but, wood or charcoal are not problematic. The steel when processed shows all the components of the alloy of which carbon is one (in fact in tamagahane the most important) and it is differentiating the C12 and C14 that provides the date.

 

Japanese folded steel: This steel was made in A.D. 1995 for use in the traditional Japanese sword-making industry. It was smelted in small batches using only modern charcoal. The radiocarbon date obtained for the steel was in accordance with the date of presumed manufacture. This piece of steel is the youngest iron-based material to ever be radiocarbon dated.

 

Japanese tanto tang: Some years ago, an old knife was given to a Japanese swordmaker (Yoshino Yoshihara) to be reforged and used to refurbish and repair other blades from the same period. The tang (back end of the knife) is inscribed with the date A.D. 1539. The swordmaker dismantled the tanto, keeping the blade for repair work and giving the tang as a gift. The radiocarbon date obtained for the tanto tang was in accordance with the date of presumed manufacture.

 

Himeji castle artifacts (pinch dog, large nail, small bracket, medium nail, and reforged nail): There have been fortifications in Himeji since A.D. 1333. Today’s castle was built in A.D. 1580 by Toyotomi Hideyoshi and enlarged some years later (A.D. 1600–1609) by Ikeda Terumasa for the Tokugawa Shogunate. The five-story castle has been home to 48 successive lords. While undergoing restoration about 35 years ago, some iron-based materials were removed from the castle in Japan.

 

The authors were able to obtain four pieces from the castle, plus a nail and a paperweight (see Figure e) that had been reforged (mildly, using low heat) from castle materials.

 

In radiocarbon dating these items, three pieces were found to be in accordance with the original building of the castle (pinch dog, large nail, small bracket) and the other (medium nail) to be in accordance with a later remodel. The reforged nail appeared to be almost 2,000 years old, and, therefore, must have been reheated using either coal or a mixture of charcoal and coal. Since coal was used, the date of original manufacture for this nail cannot be determined using radiocarbon dating.

 

Nikko Shrine, large bracket: The Shrine in Nikko was constructed as a memorial to the warlord, Tokugawa Ieyasu, whose shogunate ruled Japan for 250 years. Tokugawa Ieyasu was laid to rest among Nikko’s towering cedars in 1617 A.D., but it was his grandson, Tokugawa Iemitsu, who commenced work in 1634 A.D. on the shrine that can be seen today. The original shrine was completely rebuilt in 1818 A.D. The authors obtained what appears to be an iron brace, possibly from one of the large doorways in the shrine. It was assumed to originate with the 1634–1636 A.D. construction. The radiocarbon date, however, accords better with the 1818 A.D. reconstruction.

 

John

[Ford Hallam]

This may be the article you referenced, John

 

Fascinating stuff

[John A Stuart]

Yes, that's the article from JOM. Still way beyond chipping a piece of nakago for a quick date. The cost, don't you know!!! John

[Carlo Giuseppe Tacchini]

Nice reading. Downloaded for future reference. Thanks for sharing, John and Ford.

[cisco-san]

Very interesting article !!

[estcrh]

John, thanks for this information, I have been looking for a way to date some Japanese chain armor other than by radiocarbon dating the fabric its sewn to, this gives me a new approach.

[Takahashi]

Thank you John for the information.

 

I was already wondering if such a way of dating swords would be possible since looking at the jigane alone might not be sufficient anymore to date swords properly. I read that modern Japanese swordsmiths have improved their forging of jigane to such a degree that it is sometimes even for professional appraisers not possible to identify them as modern swords.

 

The question is how much material do you need to use the radiocarbon dating method? If it causes severe damage to the sword, it would be out of question to use the method on old nihonto.

 

Cheers,

[John A Stuart]

Sure, small amounts are needed. It is in the article;

"In the late 1980s, radiocarbon dating by accelerator mass spectrometry (AMS) became common. This new methodology required only 1 mg instead of 1 g of carbon. Cresswell4 miniaturized van der Merwe’s extraction technique and dated 12 different iron artifacts.4–8 Sample sizes in these studies ranged from 3.4 g for an iron bloom (0.4% carbon) to 274 mg for a high-carbon (1.79% carbon) wootz steel."

The sample sizes required are even now smaller and even rust scrapings can be used as per the article. John

[loui]

So, do they have a suitcase size analyzer to bring to shinsa?

 

Very interesting - thank you for posting.

 

Louis

[John A Stuart]

Hi Louis, I think carrying a linear accelerator might be problematic. :lol: You are close to Chalk River near Petawawa where you may get some help. There used to be a Dr. Stinson that was an expert on proton bombardment of metal targets, but, I expect he is now retired. I knew his daughter. Anyhow, all kidding aside, it would be very expensive. Maybe someone at the U of Toronto? What a tool it would be, eh? John

[loui]

Ya, it was a bit of a joke:) Maybe it will be an Iphone app one day:)