How many Times are Katanas Folded?

by Niklas Feurstein
6 comments
Folded Steel Katana Alternating Layers

I am sure you already heard those insane claims of people: Katana folded over 1000 times. That’s complete nonsense. In this article, I want to show you how many times katanas are folded in reality.

Let’s get right to it. How many times are Katanas folded? Katanas are usually folded between 8 and 16 times.

There is a specific reason why people say that their katana is folded over 1000 times. Read along and we will unveil the myths about folded steel katanas.

What is Folded Steel?

First things first, folded steel isn’t a steel type like carbon steel. Folded steel is a forging technique applied to mostly carbon steels (10xx series).

The process is mostly self-explanatory. As the name states, the metal is forge welded, folded and welded again.

Why are Swords Folded?

Most Japanese swords were folded. Here I want to give you a quick history lesson. In case you aren’t interested just move on to the next part of the post.

Most iron deposits in Japan contain ore with very high carbon content. This iron was called Tamahagane or pig iron.

As this steel contains 4-5% of carbon it is unsuitable for blade forging. This carbon content would make every sword break extremely easily.

So, the Japanese swordsmiths had to come up with a solution to this problem. They discovered the process of folding steel.

Thereby, they could remove the impurities in the steel and reduce the carbon content.

What are the Effects of Folded Steel?

Holding my Katana

Every time the steel is folded you create more and more overlapping layers. These alternating layers greatly enhance the toughness of the blade.

Furthermore, they add to the unique design of a katana. Everyone can spot a katana by one of its prominent features, one of it being the layers created by the folded steel.

How many Folds does a Katana have?

Ok, this is the part where it gets tricky. Don’t worry it confused me in the past as well. However, I think I came up with a great explanation for this process.

Let’s compare steel folding to folding a sheet of paper. You start with a single layer. When folding it once you have two layers. Folding again results in four layers.

The next time you fold the paper you have 8 layers, 16 layers, 32 layers, 64 layers and so on. You see each time you fold the paper/steel the number of layers doubles.

The same principle applies to folded steel. After folding a blade 10 times you have 1024 layers. Folding 16 times results in 65 thousand layers.

This is the reason why people say their katana is folded 1000 times. Those people are confusing the number of folds with the layers created.

Undoubtedly a lot of online stores do that. A blade which was folded 65 thousand times sounds way more impressive than a 16 times folded one.

After all this is just a huge marketing/promotion trick. Even if the shop owners “artificially” increase their folding counts this confuses a lot of people. Furthermore, I really hate this approach as the stores just lie to their customers.

Conclusion

I came up with the idea to write this article because most online stores “cheat” when stating their steel fold count.

This leads to a lot of confusion on the customer side and makes it difficult to compare the correct data with the incorrect one.

Store A has a sword that was folded 16 times for example. However, Store B advertises their katana which was “folded” 1024 times.

Someone who doesn’t know how folding steel works might be enticed to buy from store B, although store A might have a better offer (and a blade which was folded more often).

That’s quite a pity. I hope that I could reach a lot of people with this article and shed some light on this common misconception about katanas.

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6 comments

Thomas Aasen 20. May 2021 - 13:28

I wonder if it’s possible to make SanMai blade out of Tungsten core and Titanium folded around the outsides?
Then you will get some of the hardest “steel” in the world in middle for cutting, if it’s possible to make it as sharp as a razor or an High End Katanaa.(Maybe even sharper?) And you would have the genuine flex and also the positive abilities of Titanium laminated around the W. So, a core of W-Tungsten for cutting and sharpness, covered with both hard and flexible Titanium, would that be possible, and would/could this be a great sword? The lightness of the Titanium balancing the heaviness of W. If this could be possible to I know a lot of tools will be broken under the process, a lot of work, maybe years with planning and designing and the work itself. Maybe other metals also need to be used between the W and Ti to hold it together, maybe steel of some type. The most important is of course the edge, but also not to forget the flex, the weight, balance and holding this, making it as one part of a “steel” blade. I’ve heard that CPV-3 is very good if done right, that goes for all of course (heattreatment, cleaning, layers, good steel, depending how you make the steel and blade). Also T6, especially and T10 I’ve heard as modern super steel for Japanese swords. And of course we must not forget a well made, top notch Damascus made perfectly in any ways possible.(rare and expensive) + the legendary Russian “Wootz” or “Bulat” steel(I guess these two are the same. And I also wonder if it’s close to Damascus?). Would be interesting to get some light shared on these 2-3 types of steel, please. As I read, I see they use W-Tungsten in some types of steel, and most steel are put together with different components. Would be interested to find out a new type of steel using both old and new for a short sword, Wakizashi. But I’m really trying to find the perfect Wakizashi since that’s the most useful sword in modern combat. Either you are close enough and caan use it, or just some feets away, then you have your gun. A large Katana has nothing to do in mother wars. Short swords and Tomahawks and a multiknife or/and a smaller knife.
So, please take your time and see what you think would be the best Short Sword today. It must cut like nothing else. Body parts shouldn’t be any problems without protection. It should pierce good as well, so a strong and a rip that can pierce very good I a must. So this is also something to think about, how should the tip be? And I, personal, believe that a short sword with a nice bend in the blade, is a must.(I’ve even though about Sakabato, a reversed blade. Anyway, a curved blade cuts much better, with ease. For a short sword, you will also get a better balance to it when done right. So now you have a cutting and piercing sword with excellent balanse, grip and steel(we’ll find it, even if it will cost crazy much 😊). And this sword will stay sharp for long, if we find the right cutting steel. So, will anyone help me find the perfect short sword, a new area, so it don’t need to look like a Wakizashi, just size comparing, maybe even smaller I would like. Wouldn’t be to bad with a akull-crusher back in the handle, if you had to turn fast. Modern sheat of Kydex, maybe a mix with wood, leather, mm? Multicarrying(on back, upside/down, sideways, in front and so on, full of adjustments for fast pulling the sword out. Maybe different ways of getting the sword out? The original, straight out, sideways(just a little “click” from the handle, and you stand with it out, in the same posission as the sheath. Here we can find many nice alternatives, but remember, Zen-like Simplicity is the way to go. Lots of nice and important new creations for serious warfare where every second counts. And a blade that stays sharp as long as possible, because few in the Military are professional sword sharpeners, therefore the BEST blade that can be made in these days. Who says you only need one steel, like T6, or two, like SanMai, with the hard cutting edge in the middle? In old Japan they used sometimes 3 different steels. Names as the famous “Soshu Kitae”, a seven layers method used by Sword Smith, Masamune and “Orikaeshi Sanmai”. These contained three types of steel, Hard steel, Medium steel and Soft steel..
I wonder if it’s possible to use modern steel for Damascus, Wootz and Bulat or adding all 3(or 2)😊. You have to forgive me my ignorance of these matters, but at least I hope I can provide with some ideas. What do you think of all this, and the readers and Smith’s who may read this? Any suggestions of other steel little known and not mentioned? What would you have used and done? Maybe tried and experimented with? I truly hope something good comes out of this with so many Master Smith’s in the world. Why not talk to Professors in metalurgi? Maybe they know ways to mix and Trix to make something exciting and important?
If someone really are as much into this as me, and are a Smith or Professor and want to find and make something the world haven’t seen yet, it would light up my heart.

Thankyou for reading all this, and that you found it interesting.

Most sincerely

Thomas

Reply
Niklas Feurstein 21. May 2021 - 20:20

Hello Thomas,

thanks for your post. You managed to set forth some interesting points. Your idea to create a base from tungsten and titanium is very innovative. A benefit of a titanium blade would be that it is very lightweight. However, we also need to consider that its edge retention isn’t good due to its softness. Depending on the amount of tungsten steel used the blade becomes brittle and will shatter easily. But I need to mention that I am no smith so hopefully other people can give you a more detailed answer.

As described in my complete sword steels guide T-10 makes for very good blades with high durability (but is quite expensive). Sorry if I am wrong here but I think the original recipe for Damascus steel was lost. So, I don’t think that modern replicas offer great performance.

It’s really difficult for me to answer your question on what I think the best type of short sword is. All swords that were used throughout history had their advantages and disadvantages. You placed particular focus on the edge of the blade. I think that beyond a certain point further increases to a sword’s sharpness is useless. (Take a look at this post: What can a katana cut through?)
Regarding steel types, I must admit that I am rather fond of the more common ones such as 1060, 1095 or 9260. Performance-wise T-10 steel surely is superior (provided it is correctly tempered!). In my opinion, a curved blade like that of a katana doesn’t make a difference. If one wants to benefit from the bend, it needs a stronger curve like that of a scimitar for example.

Personally, I have taken a liking to the tanto. Please forgive me for bringing up a knife when you asked about short swords. It is a minimalist weapon, weighs “almost” nothing and can be used everywhere. When I first held a tanto in my hands I was astonished as it had a (total) length of roughly 40 cm. The wakizashi you mentioned has a blade length of 2 shaku while a tanto has 1 shaku (surprisingly that is still a lot). Thanks a lot for your interest in this topic, I realized that I should further expand my sword steels guide.

Best regards
Niklas

Reply
Hommy 6. May 2021 - 14:08

Wonderfully clear, concise, and deeply informative article.
Thank you!

Reply
Randy Emile Henaire 24. March 2021 - 5:26

Perfect description bro! Fist bump

Reply
Brandon Bach 8. February 2021 - 5:53

Thank you so much I was thinking I would have to spend 4 days and 16 hours just to fold the metal 1000 times

Reply
Keith Wilson 23. April 2020 - 22:49

Brilliant information totally fascinating and educational settled a lot of myths

Reply

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