hamons

[Mike Davis]

im assuming the "hamon" is the tempering line on a well made blade. i am curious, how do you achieve this? i know this is a noob question but i wont learn if i dont ask.
thanks
mike

 

[Doug C]

The hamon is the temper line,some use clay coating on the blade to achieve this.The experts will be along shortly to answer your question better than I.

 

[mete]

Please call it a hamon because it has nothing to do with tempering. It comes from differential hardening [various ways to do it] which results in the spine becoming a microstructure of pearlite and the edge becoming a microstructure of martensite. These two structures polish and etch differently so it shows on the finished knife.

 

[Doug C]

Mete,
I am wrong.
It is just that some of the makers I buy knives from lists "hamon/temperline" in there specs.It is confusing.

And needlessly so.Thanks for clarifying that.

:thumbup:

There are some amazing hamons out there now,aren't there?

Doug

 

[Stacy E. Apelt - Bladesmith]

The hamon is the transition line between pearlite and martensite.There is often a troosite portion to the boundary.It is created by having the edge cool to martensitic steel faster than the spine,and allowing the spine to continue cooling at a slower rate to form pearlite/troosite.The two main ways it is done is by clay coating portions of the blade and full quenching (or interrupted quenching), or by edge quenching.As mete said,it is formed by quench not tempering.Thus it is a quench line,NOT a temper line.The different steel structures polish to a different look,and with proper etching and polishing can show a dramatic contrast.Not all steels are suitable for getting a good hamon.The 10XX series blade steels do well.

 

[RogerP]

Doug, it's easy to see where you got the idea from. "Temper line" has to be one of the most misused terms in all of knifedom. Now if someone would just explain to me the difference between a choil and a ricasso....

Roger

 

[David Schott]

Ive gotten into hamon work lately. WHen I make a blade without one, I want it to have one. For whatever reason some love them, some dont....to me they are an elusive aesthetic trait that a knife can have that at the same time reveals the real nature of heat treating.

While i am no expert, my method is as follows:
-Finish blade to a rough grit to give the clay something to stick to
-apply clay with a pattern on the top 1/3 of a blade. Any patterning I do is mirrored on both sides.
-Realize that the pattern you apply will not exactly follow the hamon it will produce. You are moving around heat, not painting the hamon.
-Heat the blade lightly to cure the clay, let it sit overnight under a hot shop light or cure it with a torch. If the clay is wet, it will often pop off in the forge or upon entry into the quench before it does its job.
-heat the whole blade normally, making sure that clay gets up to temp. Its not insulating the blade from heat. The clay will be glowing red just like the steel when its ready for quench.
-Plunge the whole thing into the quench or you can try an edge quench.
-With 1095, you have a fraction of a second to get the steel below the nose. The clay serves as a bigger mass of heat and at this point does insuate that steel from cooling rapidly enough to achieve full hardness. The steel will harden in the non coated areas normally, while a general line will develop near the clay edge where the steel is unable to harden effectively.
-Scrape off any clay that did not come off in the quench and then finish the blade just like any other blade.
-Polishing a hamon is a whole other monster. Getting the subtle wisps and details is a process in patience, etching, polishing, etc.

When it comes down to it, its all in the HT. Some hamons are crazy and are done with no clay but very precise and accurate heat treating. I have yet to achieve a wavy, wild hamon without clay, but I am working on it!

 

[Whit]

Just wanted to say that it's too bad that the cover of the latest (or was it last month's) Blade Magazine says "Temper Lines" I don't imagine that will help in getting more people to use the right term or understand what they are looking at.

 

[Doug C]

Roger,
The ricasso is the part of the blade behind the plunge line to the handle/guard,the unsharpened part of the blade from the spine down.
The choil is the last sharpened area at the back of the blade,where the plunge line runs down.Hence Spanish choil.Not sure if I like 'em or not.

At least this is what I've been led to believe.
Doug.

 

[DAMNENG]

The hamon is the transition line between pearlite and martensite.There is often a troosite portion to the boundary.It is created by having the edge cool to martensitic steel faster than the spine,and allowing the spine to continue cooling at a slower rate to form pearlite/troosite.The two main ways it is done is by clay coating portions of the blade and full quenching (or interrupted quenching), or by edge quenching.As mete said,it is formed by quench not tempering.Thus it is a quench line,NOT a temper line.The different steel structures polish to a different look,and with proper etching and polishing can show a dramatic contrast.Not all steels are suitable for getting a good hamon.The 10XX series blade steels do well.

Stacy
Thanks, In the ten years I have been reading on heat treating, I had never heard the term troosite used before, or if I did it never sank in. I looked it up--- tempered martensite.

Jim A.

 

[Jared Stenoien]

how does the hamon actually affect the performance of the blade compared to simply tempering the spine blue for toughness?

 

[Mike Davis]

you guys are great! always i get a fast response on my questions. its nice to have a forum full of cool educated people that are willing to help out newbies like me. you guys rock thanks for the info. ive read that some people (after tempering plage the spine of the blade on a hot peice of coal to partially normalize that area of the knife to create a hamon. does this sound plausible or bs?

 

[raylaconico]

It's not usually done this way but you can actually get the line in the tempering process. At least with O1. I'm not sure about other steels. After oven tempering a fully hardened blade, submerge the edge only in a metal baking pan then torch the spine until blue. This will give a "temper line". It's not very bold or dramatic but it will show when etched with ferric chloride..

The word hamon is Japanese and is part of the Japanese sword. I wish there was an official English term for it but for now I guess we can call it "hamon" "temper line" or "hardening line" just as long as we know what we mean. Just my 2 cents.

-Ray Laconico

 

[Stacy E. Apelt - Bladesmith]

The hamon does not affect the performance of the blade much at all.It does affect the price of the blade quite a bit.It shows that the blade is properly hardened into two(or more) different steel structures.This can give the blade more flexibility and a harder edge.
Ray is right that a differential temper can show a line.It is not a hamon,but a true temper line.All the steel is martensite,just tempered to different degrees,with a sharply defined boundary.

 

[fitzo]

There is a good discussion of the terms "bending" and "flexing", how they are quite different, and how they apply to differential heat treated blades in this thread:

http://www.knifenetwork.com/forum/showthread.php?t=30335&highlight=torque+wrench

 

[Doug C]

Had to post a hamon,first hamon I saw today,it's one of Don's.
This is not a temperline,it is a hamon.