Question: Ed

[Gary Mulkey]

Recently you answered my post on hamons and I had a thought and wondered if you have experimented with it. I was wondering how deep a hamon goes into the blade. If it is very deep then one might water quench a high carbon steel without worrying about cracking during the quench by leaving extra thickness to the bevels and grinding it away after H/T. If this doesn't remove the hamon then it might work. I'm in the process of trying this but too soon to tell about success.

In the past I have only removed a small amount of the blade after clay tempering. Have you ever tested how deep the hamon goes?

Gary

[Teknition]

Hi Gary,
I see Ed hasn't seen this one yet, so I'll give it a go.
A hamon is just a line or pattern (depending on if you used clay or not) between the steel that hardened and the steel that remained soft
As long as you aren't working with a shallow hardening steel the hamon should go all the way through the steel.

[Burke]

The hamon does go all the way through the blade but gets closer to the edge in the center of the blade somewhat like a v if looked at in the cross section. The thickness of the blade when quenched determines how steep the sides of the v are. if you would like to see this take a quenched blade and break or cut it into then polish and etch the cross section.

[Ed Caffrey]

I agree with Brad. The hamon, which is nothing more than the visual indicator between two areas of differing hardness goes all the way through the blade. I'm fairly certain of that to at least .100 thickness.
I have been experimenting with different methods of clay hardening as time permits, but I'm still a long ways from being satisfied that I know what I'm doing. I have great success with the medium carbon steels and the W series like I mentioned before, but my goal is to figure out a way to obtain finer control on the higher carbon steels, specifically 1084 and 52100. I've had some good preliminary results with 52100 and RR thermit welding clay, but control on the 1084 is still elusive. Maybe between us....and anyone else who is working with it...we can figure this thing out.

I'm half suspecting that the control is going to require sticking with either the W series or medium carbon steels....but you never know. I've stumbled upon other things that I didn't think were possible, and hopefully this will be one of those too!

[Burke]

Hey Ed,

I have been playing with 52100 for a long time and have developed a method in which I can get a nice wavy hamon on it but I have also decided that it is not possible to get all the activity with this steel that is possible with the simple steels.

[ranger1]

I use clay(satinitie) to help give some design to my homons.Have had good sucsess with hamons on 1095 quinching in peanut oil.They do go completely threw the blade.I tried water quinch and repeatedly had cracking.Those small ones you dont find until you get to about 1000 grit.Your hamon will disappear when grinding then start to reappear at about 600 grit will become more visable at 1000 grit and really start to show 1500 & 2000 I then use lemon juice to really bring it out.then polish with a cotton rag (T-shirt) and a fine metal polish. This is just my experiance and methode.I'm sure Ed can explain it better and give alot more pointers.

[Woodchuck Forge]

Gary,

As stated above normally the hamon goes thru the blade. However there are those who can get a dramatically different pattern on either side. Take a look at Walter Sorrels' web site. He has one blade with a really nice wavy choi on one side and a straight hamon on the other. So there is something to your thoughts on the depth of the hamon. However that said, in reading The Craft of The Japanese Sword, the blade is left relatively thick and then finished shape and polished are completed after heat treating.

Chuck

[ranger1]

Walter Sorrels has a great DVD out on making homons this is where I learned to make a hamon.Along with Ed's basic forgeing DVD. Both are worth every penny.

[Gary Mulkey]

Yesterday as an experiment I clay tempered a blade blank which I profiled but did not grind any bevels (3/16" 1095). I intentionally gave it a coat of satanite with a scallopped edge just to see how that would transfer to the finished blade. I have it heat treated & water quenched. The satanite popped off immediated on immersing in water as expected but I got no visible cracking.

I tried to duplicate the pattern of the satanite on each side but sure that it wasn't exact so I'll just have to hope that the resulting hamon maintains the scallopped shape through the blade. I've never ground a hardened blade so this will be virgin ground for me but even if the experiment fails it should tell me something.

Gary

[Teknition]

Very interesting post on having a different hamon on each side of the blade, I havent seen that yet but will have a look. I've never tried to get different hamons on each side of the blade.

Since the steel when quenched cools from the outside toward the center of the blade, I would assume if you were to clay coat the blade with a different pattern on each side of the blade it would be entirely possible to get a different patterns on each side that would meet roughly in the center of the steel. I would also assume that you would have to try to balance the hardening rate of each side of the blade in order to avoid warpage when quenched.

[Doug Lester]

Ok, guys. Here's my question about hamons. What do they prove? Are they just the fad of the month or do they really show something? I understand that if I see a hamon on the blade that I can assume the blade was differentially heat treated but does it really have anything to do with the quality of that blade over one that does not display a hamon?

Doug Lester

[Teknition]

In my opinion a hamon will let you know a few things about a blade.

When a hamon is present you can pretty much bet that the blade was hand made. I haven't seen any factory blades with a hamon for the simple fact that its not cost effective to batch harden blades this way. I suppose this can be a good or bad thing, depending on who made the blade and how well they can perform the heat treatment. Just because you can make a hamon doesn't necessarily mean you can get the most out of that steel.

A hamon also tells you the blade is differentially hardened. There are different schools on this. Some believe it makes a tougher blade, others believe that its not necessary to harden a blade in this fashion to get the same toughness.

A hamon also looks very cool, which helps the maker sell blades. Much like pattern welded blades, a buyer looking at a nice active hamon or a wild looking pattern is going to sell alot easier than a buyer looking at a plain looking blade.

Personally I think some of the extremes of toughness some makers are aiming for is a bit of overkill. Do I really need my 4" hunter to be able to bend 180 degrees, 35 times? Probably not. I would much rather have a 4" hunter that was able to obtain a killer edge and hold it forever. For a survival knife on the other hand, edge retention isn't as important as the ability to use it for a prybar.

There is always a trade off in the heat treating of a blade and its a fine balancing act that the maker goes through to achieve his requirements of the steel he is using.

I think this is where the differential hardening comes into play, you can aim for a higher hardness of the cutting edge for edge retention, and still have a soft spine for toughness.


These are my thoughts, others may have different views

[AUBE]

What type of hamon are we talking about/aiming for? With a simple hamon that shows a strong line but very little activity it will go all the way through the blade and show up the same (or near the same) on each side. By simple hamon I mean one like this (I did that hamon on oil quenched 1095...sorry for the big pic, not sure how to shrink the display size on one that is already uploaded)

If you are looking for lots of fine activity below the hamon a lot of that is surface and can vary from side to side. When aiming for high activity I've read that it is a good idea to try and remove as little material after heat treat as possible. You need also need to finish the blade a lot better to bring out all of the activity that will be masked at lower grits. By lots of activity I mean a hamon like this
(that is Don Foggs beautiful work)

If the clay pops off too early during the quench it can ruin the hamon. I like to cut off small lengths of wire and bend them to C shapes then place them along the spine while the clay is still wet. This keeps the clay on the knife as it moves around during quench.

[Woodchuck Forge]

It does not appear that Walter has that blade on his site any longer. But it was very impressive.

Chuck

[Gary Mulkey]

Unfortunately my experiment with 1095 didn't turn out. After water quenching the 3/16" blade blank I got the hamon design that I wanted but found that the blade had internal cracks near the hamon. These cracks weren't visible on the surface but only revealed themselves after grinding the bevels and thus ruining the blade. I guess it's on to using a lower carbon level steel. Oh, well. C'est la vie.

Gary