Hamon: Thing of Beauty of flaw in final finish?

jimh0220

jimh0220

Joined
Apr 15, 2008
Messages
3,010
So.....

The hamon. That squiggly ghost line on custom knives. A left behind remnant of the heat treat, or a badge of honor? Amazing custom knives sport them, yet even the highest end productions seem to be missing them. Why? Could it be viewed in the production knife world as a flaw in the finish, or is it a custom touch that the production models have forgotten?

I think they look like someone forgot to polish out a flaw. But that's just my .02.

Your opinions?
 
The hamon is from differential heat treating, which most production knives never go through. It was used in swords to make the edge a little harder without making the spine harder. The blade is usually covered with different thicknesses of clay to keep it from getting hot fast, it also takes longer to cool so when the clay is removed that part of the blade is a different color. This is a very simple explanantion, wait for someone else to come along and correct me.
 
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Hamons can't be done in large batches hence you don't see them on production knives. ...to my knowledge. .. ever.
 
My thoughts are that there aren't many high carbon steel folding knives out there. We have switched to stainless knives and tool steels which to my knowledge cant have a visible hamon.

Like already mentioned above it takes lots of hand work and a personal touch that machines cant duplicate.

I personally love Hamons because they give a one of a kind uniqueness to every knife. Not one hamon is the same. As the samurais used to say... its the soul of the sword and only a properly done hamon can bring the sword to life.
 
Bigfatts said:
The hamon is from differential heat treating, which most production knives never go through. It was used in swords to make the edge a little softer so it wouldn't chip or shatter without making the spine softer. The edge is usually covered with clay to keep it from getting hot fast, it also takes longer to cool so when the clay is removed that part of the blade is a different color. This is a very simple explanantion, wait for someone else to come along and correct me.
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Excellent explanation. :thumbup:
 
Bigfatts said:
The hamon is from differential heat treating, which most production knives never go through. It was used in swords to make the edge a little softer so it wouldn't chip or shatter without making the spine softer. The edge is usually covered with clay to keep it from getting hot fast, it also takes longer to cool so when the clay is removed that part of the blade is a different color. This is a very simple explanantion, wait for someone else to come along and correct me.
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I always thought it was the other way around. Harder edge for better edge retention and softer spine to make the blade tougher.
 
Swamp Rat used to do a differential heat treat, with the hamon becoming visible if you stripped off the coating.
ESEE used to use a DHT, but hasn't for over half a decade.
TOPS also currently uses a DHT on some of their knives.

These are the only three production knife companies I know of who offer, or have ever offered, differentially heat treated blades.
 
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So, understanding this, and though this might be a totally separate topic, if differential heat treatment makes a superior knife treatment, why do, at least at the high end, do production makers not do this. Purposely turn out an inferior product? Doesn't seem right. Plus, different companies claim to differentially heat treat blades regularly, yet, alas, no hamons. Are they lying, exaggerating, or just applying more work into the final finish?
 
A DHT doesn't always result in a hamon.
Also, this has all been discussed here before, and the answers to any questions you may have can easily be found through Google.
 
jimmyd1982 said:
I always thought it was the other way around. Harder edge for better edge retention and softer spine to make the blade tougher.
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That's what I was thinking too... :thumbup:

Dan57 said:
I'm pretty sure Swamp Rat used to do a differential heat treat, with the hamon becoming visible if you stripped off the coating.
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The Ratweiler and Chopweiler were two SR knives I had where you could see the hamon... On either knife it's roughly a quarter inch up from the cutting edge...

C360_2012-10-04-21-25-01.jpg
 
jimh0220 said:
So, understanding this, and though this might be a totally separate topic, if differential heat treatment makes a superior knife treatment, why do, at least at the high end, do production makers not do this. Purposely turn out an inferior product? Doesn't seem right. Plus, different companies claim to differentially heat treat blades regularly, yet, alas, no hamons. Are they lying, exaggerating, or just applying more work into the final finish?
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Simplest explanation is that it is superior for some users, in some cases.
Also, since it needs to be applied by hand, it really isn't feasible for high production manufacturers.
My opinion is that's why the production companies invest in "super" steels, and use different steels for different knives. They choose a material that will best suit the size, shape and intent of a given blade, but can still use mass production techniques to manufacture them.

That's not to say that custom makers choose inferior steels. You're paying a premium for a premium product. They can afford to spend a little more time putting the ideal heat treat on each individual blade.
Plus, it looks cool.
 
The hamon indicated a line of demarcation where the spine is softer, and the edge is harder. If you watch the process, the thicker clay is at the spine.


Of course, Japanese swords had quite a few different construction methods involving layers of lower carbon and higher carbon steels. Sandwiched, inlaid, wrapped around. Hard edge soft sides. Hard sides soft core. Hard edge and hard spine but soft sides, etc.


Hamon's are beautiful because of the amount of work it takes to get them to appear. You don't pull a clay treated knife out of the quench and see a lovely hamon, or nice temper line.

They take a lot of finishing work to get. It is a skill, and an art. Ask a custom maker who is learning to try and get a well defined hamon line. Lots and lots of steps, and still, often it does not turn out. Nothing "left over" about them.


To get the really fantastic hamon lines you see, often they are using a brine quench (salt and water). This process alone can destroy 1 in 3 blades or more, even for expert makers. They simply crack and fail. I have seen video's of clay coated swords being quenched, and it is fantastic how much the steel bends and then curves back from the different cooling rates!



For modern, high tech steels, the differential heat treat is not really necessary.

It is also not really necessary with short blades either. It is just an extra step that shows skill, and adds beauty.


Many steels won't show any hamon line or even a temper line even if you try.


jimh0220 said:
So, understanding this, and though this might be a totally separate topic, if differential heat treatment makes a superior knife treatment, why do, at least at the high end, do production makers not do this. Purposely turn out an inferior product? Doesn't seem right. Plus, different companies claim to differentially heat treat blades regularly, yet, alas, no hamons. Are they lying, exaggerating, or just applying more work into the final finish?
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A simple answer would be "NO".


Differential heat treat may not yeild a very visible temper line on some steels. It will have a harder edge and softer spine, which is the desired result. Even if finished out properly, it might be nothing more than a barely noticeable line. Or not at all.

Modern "super" steels may not show much improvement from differential heat treat, and clay coating to try and get a hamon would be counter productive.


Also, differential heat treat, and a heat treat protocal that produces a wavy hamon are completely different.

A softer spine and harder edge are considered beneficial in knives and swords that will undergo impact and stress of impact.

a 4 inch blade is just not going to experience the same levels of forces.

A 4 inch folder blade can be harder, even mono tempered with no ill results. That same steel, taken out to a 12 inch blade at the same hardness may chip, crack or break if you exert chopping or impact forces.

It's apples to oranges.

So many things enter into the equation. Length, spine thickness, steel choice, uses, etc, etc.
 
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jimh0220 said:
So, understanding this, and though this might be a totally separate topic, if differential heat treatment makes a superior knife treatment, why do, at least at the high end, do production makers not do this. Purposely turn out an inferior product? Doesn't seem right. Plus, different companies claim to differentially heat treat blades regularly, yet, alas, no hamons. Are they lying, exaggerating, or just applying more work into the final finish?
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Not all steels will yield a strongly visible hamon from differential heat treatment. And even steels that yield a high-contrast hamon require special finishing to make it really strong and obvious. Likewise, the complex ones you see on custom pieces come from careful application of the clay to create a desired pattern. Most differential heat treatment on modern knives would look boring because there isn't a lot of "activity" to it. It would almost look like a hazy lamination line--fairly uniform along the length.
 
The real reason why you don't see many knives with differential heat treating is because it's practically useless on a blade as small as a knife. They differentially heat treated swords back in the day because of an age-old problem: make it hard, and the edge will be sharp and strong but the sword will break if it impacts too much armor. Make it soft, and the edge will not last but the sword will be tough enough not to break. Differential heat treating solved that problem by making the edge hard and the spine tough enough to absorb blows.

"Blows" being the operative word here. I've never seen a knife with a blade broken in half from normal use because you don't use a knife to hack at lacquer armor. That said, I would think that any larger chopping blade like a camp knife, "chopper," or a machete would probably benefit from a differential heat treatment (say 10" or longer). But for your 4" sheath knife, differential heat treatment is completely useless. Although a nice, active hamon sure looks pretty, which is why some makers offer knives with a hamon: it's aesthetically pleasing.

As for the hamon, that was just a side effect discovered upon polishing the blade. Since it was so pretty, it became an art form unto itself. Indeed, there's usually three people involved in the making of a Japanese sword: 1) the smith, 2) the polisher, and 3) the guy who makes the handle, wraps, etc.
 
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Magnaminous_G said:
The real reason why you don't see many knives with differential heat treating is because it's practically useless on a blade as small as a knife. They differentially heat treated swords back in the day because of an age-old problem: make it hard, and the edge will be sharp and strong but the sword will break if it impacts too much armor. Make it soft, and the edge will not last but the sword will be tough enough not to break. Differential heat treating solved that problem by making the edge hard and the spine tough enough to absorb blows.

"Blows" being the operative word here. I've never seen a knife with a blade broken in half from normal use because you don't use a knife to hack at lacquer armor. That said, I would think that any larger chopping blade like a camp knife, "chopper," or a machete would probably benefit from a differential heat treatment (say 10" or longer). But for your 4" sheath knife, differential heat treatment is completely useless. Although a nice, active hamon sure looks pretty, which is why some makers offer knives with a hamon: it's aesthetically pleasing.

As for the hamon, that was just a side effect discovered upon polishing the blade. Since it was so pretty, it became an art form unto itself. Indeed, there's usually three people involved in the making of a Japanese sword: 1) the smith, 2) the polisher, and 3) the guy who makes the handle, wraps, etc.
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1) would be the people who spend three or more days of sweat, blood, and prayers working over a huge clay kiln feeding in tons of charcoal and working like mad to smelt the black iron sand into huge lumps of steel, then break it apart with hammers, and send the different graded bits of steel and iron to the sword smiths.

It is super involved, and very interesting to watch video's.


You are also talking about artists who spend generations learning and refining the art. They did not have the benefit of super steels, modern chemistry, electron microscopes, etc etc.
 
jimh0220 said:
So, understanding this, and though this might be a totally separate topic, if differential heat treatment makes a superior knife treatment, why do, at least at the high end, do production makers not do this. Purposely turn out an inferior product? Doesn't seem right. Plus, different companies claim to differentially heat treat blades regularly, yet, alas, no hamons. Are they lying, exaggerating, or just applying more work into the final finish?
Click to expand...


Why does this have to end in 'someone is getting screwed over'? There's more than one way to skin a cat. Just because you don't see it on every production knife ever, doesn't mean they are trying to cheap out on you or screw you over. The absence or presence of a hamon is not the ultimate decider of a knife's quality. It just means there was some clay stuck on the blade when they heat treated it. It is possible to do differential HT without clay, plus differential HT isn't even always the best option for some users. It depends on what the knife will be used for, among many other considerations.

So, no, the absence of a hamon does not automatically mean a blade is of inferior quality and that the maker is a liar.
 
Magnaminous_G said:
The real reason why you don't see many knives with differential heat treating is because it's practically useless on a blade as small as a knife. They differentially heat treated swords back in the day because of an age-old problem: make it hard, and the edge will be sharp and strong but the sword will break if it impacts too much armor. Make it soft, and the edge will not last but the sword will be tough enough not to break. Differential heat treating solved that problem by making the edge hard and the spine tough enough to absorb blows.

"Blows" being the operative word here. I've never seen a knife with a blade broken in half from normal use because you don't use a knife to hack at lacquer armor. That said, I would think that any larger chopping blade like a camp knife, "chopper," or a machete would probably benefit from a differential heat treatment (say 10" or longer). But for your 4" sheath knife, differential heat treatment is completely useless. Although a nice, active hamon sure looks pretty, which is why some makers offer knives with a hamon: it's aesthetically pleasing.

As for the hamon, that was just a side effect discovered upon polishing the blade. Since it was so pretty, it became an art form unto itself. Indeed, there's usually three people involved in the making of a Japanese sword: 1) the smith, 2) the polisher, and 3) the guy who makes the handle, wraps, etc.
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Pretty much. I think swamp rat stopped doing it on their choppers because through hardened 1/4" thick knives were strong enough for any real use so why take the extra hit in cost with a needless HT step. I wouldn't say they're "useless" though. If you want real cutting performance you need to go thin. So, if you want a good cutter that's ALSO strong, it's not a bad idea to have a softer spine for an extra little bit of strength. I personally would never pay more for a hamon though.
 
That's the beauty of creating sharp objects: There are thousands of different ways to create a knife/sword for thousands of different purposes. It just so happens that the differential heat treatment caused the hamon to show up, thus making the knife attractive to certain eyes, for some a status symbol and it's been around since. There's no "flaws" about it, it's just one of many methods used in the creations of knives/swords.
 
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