Q: Reason Traditional Hamon are Wavy?

K

KChuck

Joined
Jun 19, 2010
Messages
19
So I've been wondering for a while: are traditional hamon wavy for aesthetic or practical reasons?

Simple question which could lead to some very (and hopefully) complicated answers. I'm very much looking forward to any replies from those knowledgeable about things like metallurgy or even just general bladesmithing.

TIA!
 
They're not always wavy. Some are jagged (as in the sambonsubi) and others are perfectly straight ( as in the suguha). The design was purely aesthetic.

- Chris
 
I should also add that I have heard that on some modern steels (mostly 5160), a wavy hamon will prevent the blade cracking along the hamon during quench.

- Chris
 
While the design is basically aesthetic, the hamon serves to harden the edge for better sharpeness; also there is some evidence that it does help prevent a crack from "running"
up into the rest of the blade.

Rich S
-------------------------------------------------------
Richard Stein, PhD
Old Puukkophile
NKCA Life Member

Japanese Sword Guide
http://home.earthlink.net/~steinrl/nihonto.htm
-------------------------------------------------------
 
Rich S said:
While the design is basically aesthetic, the hamon serves to harden the edge for better sharpeness; also there is some evidence that it does help prevent a crack from "running"
up into the rest of the blade.

Rich S
-------------------------------------------------------
Richard Stein, PhD
Old Puukkophile
NKCA Life Member

Japanese Sword Guide
http://home.earthlink.net/~steinrl/nihonto.htm
-------------------------------------------------------
Click to expand...


Just as a point of clarification does the hamon really do that? Or is the hamon a byproduct of the tempering that does that?
 
butcher_block said:
hamon is not a product of temper its a product of quench
Click to expand...

Okay, you may very well be correct, I'm just going to ask though... When you say it is a product of the "quench" this would be an edge quench I assume. Isn't the hamon of Japanese swords the result of "clay tempering" i.e. clay is placed on the sword and the difference in the tempering where the clay is and is not causes a difference in the grain structure of the blade in those areas?
 
Triton said:
Okay, you may very well be correct, I'm just going to ask though... When you say it is a product of the "quench" this would be an edge quench I assume. Isn't the hamon of Japanese swords the result of "clay tempering" i.e. clay is placed on the sword and the difference in the tempering where the clay is and is not causes a difference in the grain structure of the blade in those areas?
Click to expand...

again, the use of the word "tempering" is incorrect when refering to a hamon.

clay is applied to the sides of the blade , with the exposed area to be hardened. The entire blade is quenched, the boundry between the clay edge is roughly where the hamon forms. The boundry between pearlite and martensite. "tempering" will not form that boundry.

I'm starting to wonder where the term "temper line" or clay temper came from. Not pickin on you, just curious....i think I'm gonna do some searching on it
 
Clay is applied before the quench (prior to heating). During the quench, the clay prevents the coated part of the blade from cooling fast enough to convert to martensite. The uncoated edge hardens fully. When etched, the acid etches the martensite of the hardened edge ('yakiba' in japanese) differently than the pearlite in the unhardened ji (and shinogiji when present). This is a similar solution to the edge quenching method used in western style bladesmithing, in that it fully hardens the edge while leaving the spine soft. Edge quenching can produce a hamon, but it cannot be used to create the intricate patterns that clay coating does. In both methods, the edge is then tempered. Tempering is the process of softening hardened steel slightly to reduce brittleness (by turning some of the martensite back into pearlite). Tempering too much will reduce the visual effects of the hamon, because it is turning the martensite back into pearlite (and can undo the effects of the hardening) — thus the acid will affect everything more evenly. So the calling a hamon a 'temper line' is erroneous — I have no idea where this term came from.

- Chris
 
SShepherd said:
again, the use of the word "tempering" is incorrect when refering to a hamon.

clay is applied to the sides of the blade , with the exposed area to be hardened. The entire blade is quenched, the boundry between the clay edge is roughly where the hamon forms. The boundry between pearlite and martensite. "tempering" will not form that boundry.

I'm starting to wonder where the term "temper line" or clay temper came from. Not pickin on you, just curious....i think I'm gonna do some searching on it
Click to expand...

Fair enough and I don't feel picked on just using the terminology as I understand it. So in reality we should be talking about "clay quenching" instead of "clay tempering?"
 
Rich S: Yaki-ire is the term for the hardening process. Yakiba is the term for the hardened portion of the blade in between the hamon and the ha (edge). I was referring to the latter.

- Chris
 
im thinking the temper line thiing came from the guys that harden a blade then torch the spine to blue or past and have a soft spine and hard edge
not sure if that will show a line or not if etched

you will tho find lots of misused terms and made up marketing crap like ice quench (wouldl love to see some one plunge a knife blade from 1500f right into a block of ice )
 
butcher_block said:
im thinking the temper line thiing came from the guys that harden a blade then torch the spine to blue or past and have a soft spine and hard edge
not sure if that will show a line or not if etched

you will tho find lots of misused terms and made up marketing crap like ice quench (wouldl love to see some one plunge a knife blade from 1500f right into a block of ice )
Click to expand...

rotfl....hey, I hear someone from the forums did that with LN !!:eek:
 
I think that the "temper line", etc comes from a common misuse of the word "temper" in place of "heat treat". To us it may seem an inane mistake, but "we" aren't the general public when it comes to heat treatment. I see this type of thing all the time in the general public's misunderstanding of computer and networking terminology. It gets just as maddening for me there...TV where they do "computer hacker stuff" is the absolute worst...can't stand to watch it...

-d
 
Well, while it may not be currently accurate from a technical perspective, The Oxford English Dictionary includes the following definitions for temper:

14. a. To bring (steel) to a suitable degree of hardness and elasticity or resiliency by heating it to the required temperature and immersing it, while hot, in some liquid, usually cold water; applied also to the hardening of copper, etc. Also fig.

14. c. trans. To reduce the brittleness in (hardened steel) by reheating it to a certain temperature and allowing it to cool. Cf. ANNEAL v. 4. [meaning: See Also: "anneal" verb, def. 4]
Click to expand...

So while the more correct, technically current term would be "quenching", I'd have to lend my support to those who might use the description, "temper line" and most respectfully disagree with those who imply that temper only means annealing since it can mean both annealing and quenching. One could further argue that, by extension, it could encompass "heat treating" in general.

I'd also like to point out that the first citation for the definition which refers to quenching dates back to Chaucer (1381) while the first citation for the use of temper in reference to annealing only date back to the beginning of the 20th Century (1925) so arguments could be made for the first definition being more proper... or that it's outdated.

Sorry to come all-over pedantic... [refrained from a really long-winded rant about computer terms being far from the only ones which are mis-used] ;)
 
KChuck said:
Well, while it may not be currently accurate from a technical perspective, The Oxford English Dictionary includes the following definitions for temper:



So while the more correct, technically current term would be "quenching", I'd have to lend my support to those who might use the description, "temper line" and most respectfully disagree with those who imply that temper only means annealing since it can mean both annealing and quenching. One could further argue that, by extension, it could encompass "heat treating" in general.

I'd also like to point out that the first citation for the definition which refers to quenching dates back to Chaucer (1381) while the first citation for the use of temper in reference to annealing only date back to the beginning of the 20th Century (1925) so arguments could be made for the first definition being more proper... or that it's outdated.

Sorry to come all-over pedantic... [refrained from a really long-winded rant about computer terms being far from the only ones which are mis-used] ;)
Click to expand...

regardless, the formation of a hamon has nothing to do with "tempering".
And yes, the shape has more to do with the smith, some showing supreme mastery of the technique by making them elaborate.
 
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