Jump to content

Do Hamons Serve a Practical Purpose?


Recommended Posts

Do hamons serve a practical purpose over edge quenching, or do the just look pretty? From my (limited) understanding they are not really needed, but in the process of getting one you curve the blade some. Aren't Japanese swords only made with a hardenable core inside softer materials?

"I have surprised myself with what I can make with simple tools when a definite need arose. I don't think a man knows what he actually can do until he is challenged."- Dick Proennke

Link to post
Share on other sites

Do hamons serve a practical purpose over edge quenching, or do the just look pretty? From my (limited) understanding they are not really needed, but in the process of getting one you curve the blade some. Aren't Japanese swords only made with a hardenable core inside softer materials?

 

firstly japanes blades are two type's of steel hard outer skin soft pliable inner core

forge into one blade lenth wise then the lower portion of the blade is hardend to get the cutting edge, the Hamon denotes the transition between the hard cutting edge the softer upper portion of the blade ,also if the whole blade were hardend it would snap from stress , or worse fail in battle .the soft inner core is even softer for flexability . in use but in essence the hamon is cosmetic off shoot of this prosess that the polisher exploites when polishing the blade , and bring out more charecture in the blade mainly for art lovers you can find all the tec term's elswere in this forum for simplicity i used laymans terms above

 

hope this helps

Terence.........(today started off perfect now --- watch sombody come and stuff it up ]

 

if it aint broke dont fix it

Link to post
Share on other sites

firstly japanes blades are two type's of steel hard outer skin soft pliable inner core

forge into one blade lenth wise then the lower portion of the blade is hardend to get the cutting edge, the Hamon denotes the transition between the hard cutting edge the softer upper portion of the blade ,also if the whole blade were hardend it would snap from stress , or worse fail in battle .the soft inner core is even softer for flexability . in use but in essence the hamon is cosmetic off shoot of this prosess that the polisher exploites when polishing the blade , and bring out more charecture in the blade mainly for art lovers you can find all the tec term's elswere in this forum for simplicity i used laymans terms above

 

hope this helps

 

So, if I got you, there are 4 pieces of steel welded together, A hard cutting edge, soft core behind that and two outside kinda hard 'cheeks'? If they would snap from quenching all the way, why wouldn't western swords do the same? They are laminated (at least in ye olden times) as well, right? It seems they are just really cool shiny things that don't do much (other then look cool).

"I have surprised myself with what I can make with simple tools when a definite need arose. I don't think a man knows what he actually can do until he is challenged."- Dick Proennke

Link to post
Share on other sites

There are more types of Japanese swords than that according to Jim Hrisoulas but those are probably the main types. You take one of the types of steel, I'll do the "hard" steel around "soft", and you take the bar to hard steel and fold it length wise to form a gutter. Then to take the bar of soft steel and lay it inside of the gutter and forge weld the two bars together. You can also do it the other way around. You can also just butt weld the "hard" and "soft" bars together. However it is done, you then forge the blade out so that the edge is on the "hard" side. My understanding is that the hamon just shows the transition between the pearletic and the martensitic steel. I find the facinating thing about this is that the old timey smiths developed these techniques without any real knowledge of what they were doing. They just learned to follow certain steps without any idea of why they were doing it.

 

Doug Lester

Edited by Doug Lester

HELP...I'm a twenty year old trapped in the body of an old man!!!

Link to post
Share on other sites

Greg,

 

The original purpose (beginning some 900+ years ago) of polishing a Japanese blade so that its hamon, hada, and other attributes are visible was very simple: so the person purchasing the blade could evaluate its investment value as a weapon on the battlefield.

 

Not only would any possible cracks, weld-flaws, or other "fatal" flaws be obvious to the evaluator, but the hamon showed it had a wide-enough hardened-steel area to allow multiple polishes (it could be sharpened many times). Visible ashi showed that cracks wouldn't propagate any further than the distance spanning the ashi. The brilliance of the hamon told how hard the edge would be, thus, how long it would hold an edge. Consistency across the hamon of its constituent crystalline structures (nie, nioi, etc.) also showed the reliability of the blade and skill of the smith. Hada showed the construction and which steels where mixed and how well-constructed the blade was.

 

As bladesmithing evolved, other attributes, such as utsuri, merely showed the skill and control over the steel and heat-treatment of the smith, as quality elevated beyond blades that just had a hardened-edge and no fatal flaws. Since many samurai were paid very little, a sword could cost as much as a year's wages, even more. So the samurai had to have some way to know that the blades they were investing in would be dependable in battle, and be able to withstand re-polishing (even if he did it himself) so it would not have to be replaced after only one or two skirmishes.

 

I like to think of it as a marketing ploy by the smiths to allow honest evaluations (you don't get good recommendations and references from dead clients) and, eventually, to show off their skills.

 

Why did they continue to polish this way? Tradition, of course. Almost over-powering in Japan.

 

Why do we do it now? Tradition, to show our skills, aesthetics, because it is cool.

 

European blades are not my forte, but I understand they usually have RC 48-56. They are, by heat-treatment alone, more flexible. The Japanese sacrificed the flexibility for a hardened edge of about RC 60 - 62. To regain some of that flexibility and shock-resistance, they developed differential hardening. I will try to find some photos of cutting exercises with modern European blades. I have seen stop-motion photos of them flexing at least 45 degrees or more mid-cut.

 

The Japanese also developed different kitae or zukurikomi--construction techniques. There are literally dozens of construction techniques, varying by school and time period. There were ones fashionable during this period and mandated by that daimyo, and of course the other one that everyone wanted because it was favored by a certain lord, etc.... Regardless, most rely on an unhardenable iron leftover from tatara smelts of tamahagane, mated with a hardenable steel. Of course, you could harden the entire blade and the iron core would not harden (except for wherever the carbon migrated into it). But that would still render a large portion of the blade too hard to flex during battle and not crack fatally. And you have to remember--by the time two or three generations had passed, this technique of diff. hardening would be tradition--which CANNOT be broken in Japan without consequences.

 

Different kitae / zukurikomi: soft skin wrapped around hard edge / core, hard skin / edge wrapped around soft core, and dozens of variants with soft core, hard edge, medium sides, etc.

 

Do hamon serve a practical purpose over edge quenching? Depends on the steel and the smith. However, for my purposes, I think it is an obvious advantage to have ashi (softer steel "veining" into the harder martensite that makes it tougher) and a visible, honest evaluation of my heat-treating skills vs. an edge quench. On a sword, anyway. Knives--well, then it is probably just eye-candy! Just my humble opinion and 2 cents. Your mileage may vary.

 

More reading on zukurikomi (construction): http://www.ncjsc.org/kitae-1.html

http://www.ksky.ne.jp/~sumie99/construction.html

 

 

Also, as Mr. Kenon Rain learned on this blade, zukurikomi plays WAAAAYYY more of a role in hamon-formation than even the clay. Just wanted to point that out.

 

Hope that helps,

 

Shannon

Edited by J.S. Hill
Link to post
Share on other sites

Do hamons serve a practical purpose over edge quenching, or do the just look pretty? From my (limited) understanding they are not really needed, but in the process of getting one you curve the blade some. Aren't Japanese swords only made with a hardenable core inside softer materials?

 

Hello All,

Who we need here is Howard Clark as he has done more that one experiment on this subject and has a wealth of knowledge.

 

I suggest he make a video detailing the complexity with hands on demonstrations...I'll be happy to film the result.

I have been trying to get Howard to do a video on this and other topics for some time..many do not know what he has developed beyond the work he presents now...he is more of a "deep river" with a slow strong current rather than the "puddle people" with a trickle of surface knowledge.

 

The issues are many as is the answer because the answer changes with the steel and construction and technique (as well as the time period and culture..yes there were even hamon on European blades)

I am sure Howard has seen this question and I am also sure he knows how detailed and slippery real answer can become....it is one of those multi-part.."yes, but" type of answers.

 

Ric

Richard Furrer

Door County Forgeworks

Sturgeon Bay, WI

Link to post
Share on other sites

Dan the danish Hobbit conducted a nice test on a cracked 1086v wakizashi (Johns Wakizashi I should add)proving that even the smallest of cracks if fatal when you have clay quenched a blade.

 

Even cutting a beer can full of water will break a sword with even a little crack in it.

Link to post
Share on other sites

Yes, have you ever tried to edge quench a katana? I imagine it would be almost impossible.

Good point. They are rather long, to say the least.

 

So, they do serve a purpose by showing how well made a blade was? And making sure that if a crack did exist they would show up easily, right?

"I have surprised myself with what I can make with simple tools when a definite need arose. I don't think a man knows what he actually can do until he is challenged."- Dick Proennke

Link to post
Share on other sites

Good point. They are rather long, to say the least.

 

So, they do serve a purpose by showing how well made a blade was? And making sure that if a crack did exist they would show up easily, right?

 

That's correct, IMHO. Hamon displayed (in plain-view) each blade's true characteristics in an honest manner so it could easily be appraised as to what could be expected of the weapon in battle. Better-made swords could fetch more money. Inferior swords would be disposed-of (recycled) so that a smith's reputation could flourish.

 

And, as Jamie pointed out, you have to understand it was an all-inclusive package with the Japanese-made blades made from tamahagane in feudal Japan. Their technology and steel didn't allow for a type of edge-quench that would have reliable results. To get the most performance they could out of an extremely poor material (tamahagane), the Japanese came up with the clay-coat / differential-hardening method. This method HAPPENED to cause hamon to form. Those selling the swords (and, subsequently polishers) exploited those characteristics to allow potential buyers to assess a sword based on a tangible, visible indicator of the care, skill, and attention of the smith to the heat-treatment of the particular blade.

 

To address your original question, the clay-coat / differential heat-treatment DOES have a practical purpose in the context of tamahagane and the smithing technology of feudal Japan (the subsequent hamon is a result of the heat-treatment and appropriate polishing work)--to make the blades function within the context of their fighting-style. The process usually induces some curve, but that can be controlled to some degree. There are MANY construction techniques used by Japanese smiths to create swords depending on era, school, fashion, and use. The links I posted contain a LOT to digest.

 

Hope that clarifies things. I would still LOVE to hear Mr. Clark's thoughts on the subject. It is often lonely on the slippery-slope!

 

Sincerely,

 

Shannon

Link to post
Share on other sites

I dont think the hamons purpose is to show how well a blade is made, intentionaly or not. The polish does show how well made a blade is but again I dont think thats the point of it. I think the polish is 95% show and 5% funciton, the function being to avoid friction when cutting larger targets like people, the higher the polish the lesser the friction generated during a cut.

 

I think the hamon was just a natural conclusion of finding the most effective way to heat treat a sword of katana shape. If you temperd a Japanese sword softer it would wrap around the target if you were even slightly off angle during a cut, if you left it hard it would snap if you hit the target at the wrong angle.

 

As for the difference between edge quenching and clay quenching? Like Ric Said I think Howard should make a video, hes an amazing man to learn from and I think he is the bloke to listern too with stuff like this.

Link to post
Share on other sites

Maybe I'm saying the same thing as Jamie but the hamon itself, a "line" that shows the border between the pearletic steel on the spine and the martinsetic steel at the edge of a blade accentuated by polishing and etching, only shows that these qualities are present. It is those qualities present that have a funtion. So a hamon, in and of itself, is not really funtional but the characteristics of the blade that it displayes are and they would be there even if the hamon was not developed. Just my point of view.

 

Doug Lester

HELP...I'm a twenty year old trapped in the body of an old man!!!

Link to post
Share on other sites

Jamie and Doug,

 

We're definitely all saying mostly the same thing, here.

 

If you'll please read my comments above I am completely agreeing and specifically stating what Doug just said. The underlying characteristics of the blade (hardened martensitic edge / soft pearlitic body) are what have applications in battle. The polished hamon only makes those attributes apparent. That is the sole purpose of polishing a blade past kaiseido. Otherwise a blade can, and was often used in battle in "shira-togi", where you only have a "white-polish" and nothing really showing other than what the foundation stones brought up.

 

The yakiba is the entire area from the edge all the way up to the nioi-guchi (the bright, silvery line demarcating the transition from pearlite to martensite). When the yakiba is in polish, it is called "hamon". It is NOT just the nioi-guchi, itself. Saying "hamon" give the context of aesthetics and implies a polished yakiba. Otherwise, there is no visible hamon. It isn't there. It is waiting to be brought out of the yakiba.

 

And Jamie is right. The polish is 95% show. So the hamon is 95% show. You have to understand that saying "hamon" in Japanese-sword circles is like saying "label". No one reads the label on something in the store and says, "Gee, this mayonnaise label has 8g of fat." NO. They look at the label and understand that it is saying something about what is inside.

 

It may be semantics, but I have a different understanding of the word "hamon". The literal translation is "edge crest", as in "family crest", as in "identity". Some say a better translation is "edge face". Togishi regard the hamon to be the face of the blade. The spirit resides within. "Hamon" is an esoteric, poetic, and religious-based idea among Shinto-ist in Japan. The hamon is the visible representation of the yakiba, the hardened martensitic edge.

 

Regardless, the hamon is a direct product of polishing a differentially hardened blade. It is NOT the martensitic steel beneath it. That is the yakiba. The hamon is the "face" of the hardened edge. If you want to talk about the martensitic structures beneath that is the hardened steel, well, that is called the "yakiba", which means, "hardened edge", hahahahaha.

 

So, you can see that saying "hamon" sets the context of aesthetics, which I went around in my second reply to this thread and spoke about the actual yakiba. "Hamon" IS the edifice of the smith's abilities. That is its only purpose. The hamon has no other purpose. It does not "do" anything, other than assess the blade's attributes. The yakiba makes it hold its edge longer due to it being a harder steel.

 

Sorry to get wrapped up in the words. I thought I had gone around them eloquently in my 2nd post. I guess some regard the hamon and yakiba as being one in the same. But there are those of us that don't....

 

Sincerely,

 

Shannon

 

I'd still like to hear Mr. Clark's comments. He always makes me think outside the box.

Edited by J.S. Hill
Link to post
Share on other sites

Very well said. To chime in with a bit of my own reasoning here: For me, the advantage of a differential HT done with clay VS an edge quench is the ability to create an irregular transition from martensite to pearlite. I feel that this has an effect on the way the blade deals with stress. It certainly has an effect on the way a crack propagates.

 

Thats just the way I feel about it though.....I could be completely full of it.

Link to post
Share on other sites

This is a very deep hole to dive into. Thus my hesitancy. Thanks, Ric, I think...

 

In context, it was just what happened when you make a low hardenability material starting with tamahagane, forge into the cross sectional shape we know as the Japanese sword, and quench it edge down in water. All the clay, and refinements of the technique are just that, refinements.

 

Wit the modern steels most of us are using, the clay is much more essential to even get a transition from martensite to pearlite, because of the Mn, mostly. It is present in modern steel as a "fix" to tie up the sulphur from using coke to fuel the furnace. With no Mn at all, there would be iron sulphide inclusions, which are in between the grains of the steel, and go liquid at forging temperatures, thus rendering the material hot short as it comes apart. So some Mn is essential with modern solid fuel steel process. The manganese sulphide is not liquid at ordinary forging temperatures, and remains a solid particle in the steel. Still crud, but solid crud instead of a slippery liquid.

 

Does it serve a practical purpose to make a hamon on a blade ? That all depends on how you look at it, and I don't know if there is a "right" answer or not.

 

The edge hard, and the back softer makes a blade not as likely to break, but more likely to bend. It is a continuous curve of trade-offs.

 

They are certainly things of great beauty and learning to control and manipulate them is both fascinating and fun, and demonstrates mastery over your material.

 

Better or worse than other ways to make blades ? I don't know for sure about that. I am still trying to figure it all out. ;)

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...