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Hi all,

 

I've read quite a few threads about hamons in this forum but I wonder if anyone knows what's going on with my blade.

 

I heat treated the blade with satanite and eventually sanded it to a 1200grit finish. At this point I can clearly see a light line were the hamon is. But when I try to darken the blade with vinegar and/or lemonjuice it has the same result every time:

 

Hamon_02.jpg

 

I used different types of vinegar and lemon juice (fresh and bottled), and applied it with different temperatures (lukewarm to near boiling point). I had a lot of tries by now but every attempt (and thus every type of acid) had exactly the same effect: The hardened steel starts to darken first. Then after a while the 'left' part of the softer steel starts to darken. The 'right' part doesn't change at all. (There is a small gradient between the red and green area. not a hard line as shown in the picture). So unfortunately etching with these acids doesn't give me a nice result to bring out the hamon.

 

I have also read that steel with more than 0.5 manganese is not suitable for hamons. This steel has 0.65 (see below for composition)
Carbon: 0.75%
Chromium: 0.14%
Manganese: 0.65%
Silicon 0.2%
(ordered at: https://www.eurotechni.com/en/dnh7-xc75-1075-1-1248.ht)

 

At this point I have 2 questions:
1. Can someone explain me what is going on with the steel and why it is darkening in this way? Especially the difference in the darkening of the soft steel.
2. Is etching in ferric chloride an option or is it impossible to bring out the hamon in this blade and should I go for another type of steel?

 

 

I'm a beginning knifemaker and this is my first post to this forum but I hope some of you people can share their knowledge with me. It would be great if I can still manage to get a nice hamon. And if not I really would like to know what I'm doing wrong so that I can gain new knowledge about this craft. Thanks in advance!

 

 

 

 


 

 

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I'll preface by saying that I am by no means a hamon expert.

 

I would say that your blue area hardened up nicely, but my gut feel tells me that your green area hardened a bit as well, especially compared to the red area.  My guess is that there was inconsistencies in the thickness of the Satanite that caused the green area to get hotter than intended and harden a bit more than you wanted.

 

That's just a guess, I'm also going to very interested in what the hamon experts have to say.

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With my limited experience, I think the blue zone has a high % of martensite, the red zone probably partially hardened so it may have around 20-30%, while the green zone is dead soft. 

 

The steel under the clay generally hardens a little bit, unless it didn't reach aus temp that is...

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What you are seeing is what that steel is capable of giving you.  The chromium and manganese levels make it a very deep-hardening steel, so while you can get a basic line, you will not be able to get the wispy cloudy look of true hamon with that alloy.  The dark part is fully hardened, the muddy part is not quite hardened, but not capable of showing the mixed microstructure of ferrite/pearlite/martensite that is the cloudy part of hamon, and the part that stays bright didn't harden at all.  

Also, you can try rubbing with loose abrasive powders above the fully hardened part to try and bring up any microstructure there is.  The uniform pressure of fine sandpaper on a hard backing tends to wash out any differences that may exist.  A little experimentation with abrasive metal polishes like Flitz or Simichrome may surprise you.  

If I were you, though, I'd find another alloy.  You want no chromium at all, and manganese below 0.35% for best results.  The silicon doesn't hurt anything.  Your alloy would be an excellent spring steel or large blade steel.  

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The previous responses are from folks who know more about creating hamons than I do, so I won't pretend to have better input.

 

One thing that I think you may be asking about that they didn't cover is why is your hard steel turning black as opposed the soft steel.  I actually can't answer that precisely.  I believe different etchants have different effects.  Also, etching a hamon will results in a different look than one that is traditionally polished.

 

I'm mostly posting to prompt someone else to answer the question that I think you asked :)

 

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21 minutes ago, Brian Dougherty said:

The previous responses are from folks who know more about creating hamons than I do, so I won't pretend to have better input.

 

One thing that I think you may be asking about that they didn't cover is why is your hard steel turning black as opposed the soft steel.  I actually can't answer that precisely.  I believe different etchants have different effects.  Also, etching a hamon will results in a different look than one that is traditionally polished.

 

I'm mostly posting to prompt someone else to answer the question that I think you asked :)

 

 

Indeed! What I've read is that the soft steel should darken with lemon and the hard with vinegar (usually). But all the different acids and methods have the same effect.

 

 

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When you use acid to etch steel there are a couple things that come into play:  Chemistry and energy.  When we etch pattern welded steels, the chemistry difference is the big obvious difference.  When you are etching things like a hamon (or other such hardening line, thin or wispy), you are looking at the energy difference.  Martensite is a stressed lattice, and therefore is attacked first by the etchant, all other things being equal.  So as others have mention with the different microstructures: your fully hardened (100% martensite) edge was readily attacked by the acid, the semi-hardened (mix of martensite, bainite, and pearlite - probably, but not the right ratio for a wispy hamon) section was next to be attacked, and your softer (pearlite/ferrite) section attacked slowest.  

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Ii should also add that the aggressiveness of the acid used plays into things a bit, too.  Generally speaking, a less aggressive acid is desired because it will be better able to show the differences for its preferred attack (you'll really see it eat at the martensite more than ferrite).  If you get too aggressive of an acid then you won't really see the difference as much because it attacks everything quickly.  Best analogy I can come up with is this:  Imagine sitting next to a road.  When you see a car go by at 90 miles per hour, then an hour later the same car passes at 100 mph.  Could you tell the difference?  Not too easily at least, they were going REALLY fast both times though.  Now imagine a car goes by at 11 mph, and an hour later again at 1 mph.  You can really easy differentiate between the second two passes.  

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40 minutes ago, Brian Dougherty said:

why is your hard steel turning black as opposed the soft steel.

 

This will happen with any acid etch, for the reason Jerrod mentioned. When people use etching on hamon, what they often don't tell you is to either re-polish the edge OR only apply the etchant to the area above the line.  And use the powdered abrasives on a soft backing.  Traditionally it was ground iron oxide scale in clove oil.  

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1 hour ago, Alan Longmire said:

  You want no chromium at all,

I believe this is debatable, at least to a certain point. This 26c3 stuff I've been using for my last kitchen blades produced what I believe to be good hamons and it has 0.3% chromium. 

 

https://youtu.be/y25e2qi71lA

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One can want no Cr, but tolerate a certain level.  

But generally speaking you want a shallow hardening alloy, and there are many viable chemistry options that will achieve this goal.  It is just that a little carbon goes a long way for depth of hardening.  

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@Alan: I have overlooked your first response, but thank you for the information. I have been trying to polish the blade with mothers mag but it just didn't came out the way I wanted. And I was already considering to finish this blade without darkening/polishing the hamon and keep that on the to-do list for a later attempt.

 

And thanks to all others who responded as well!  If anyone still wants to add something to this thread, please do. I'm really appreciating this feedback.

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1 hour ago, Jerrod Miller said:

One can want no Cr, but tolerate a certain level.  

Yeah, just don't discard a candidate "Hamon steel" because it has a pinch of chrome. That was my point ^_^

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Just now, Joël Mercier said:

Yeah, just don't discard a candidate "Hamon steel" because it has a pinch of chrome. That was my point ^_^

 

Point taken! B)  and duly noted.  

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It would be useful to see an unedited pic to see what you have, but there is nothing inherently wrong with this in a hamon - basically the part that doesn't darken wasn't brought up to critical (it is basically a form of utsuri), which shows good temp control. There maybe activities in the actual hamon which could be brought out, but this steel is finnicky and needs a lot of normalization to show much of anything...

 

That said, you would probably have better luck with ferric or even nitol...

Edited by jake cleland
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7 hours ago, jake cleland said:

It would be useful to see an unedited pic to see what you have, but there is nothing inherently wrong with this in a hamon - basically the part that doesn't darken wasn't brought up to critical (it is basically a form of utsuri), which shows good temp control. There maybe activities in the actual hamon which could be brought out, but this steel is finnicky and needs a lot of normalization to show much of anything...

 

That said, you would probably have better luck with ferric or even nitol...

 

Here some additional photos of the polished blade were you can see the area of the hamon a bit:

Hamon_03.jpgHamon_04.jpg

 

Can it still be an option to soak it in vinegar for example (for a couple of hours?) to get i really dark? And then try to polish it to a nice result with mothers mag? Or will this be a process with a lot of room for error and/or an ugly looking hamon at the end? If anyone still has a good option that I can try I'm more then willing to give it one more go!

 

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I think you have taken that particular piece of steel, with the specific HT done, to the point of what you see is what you get. Additional acid or polishing treatments might make a difference, but I doubt it will change as significantly as you are hoping it will. Quite frankly, what you have looks pretty good for your first try with a less than nominal steel for the intended outcome.

 

You have a few options at this point.

1. Chalk this one up to learning and experience, finish the handle out, and make another knife, using some of the suggestions above.

2. Fiddle around with another acid soak, further polishing/sanding as mentioned above until you grow tired of it or get a result you are satisfied with, and then move to option #1

3. Normalize that knife  and do HT again. You already know that what you did this first time did not provide the results you wanted, so try a different method. At least try some of the suggested methods above to further optimize the process.

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Excuse my ignorance but I fail to see the problem here.....

 

Are you simply unhappy with the "quality" of the hamon?

 

I got pretty much the same result with my first 4 blades in 1070, I've been using one in the kitchen for a few weeks now and I had it in vinegar for a while but it's picking up patina from use, the edge is dark and the spine/tang light grey

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Gerhard has a very good point. There is ample evidence of the hamon in the photos, and the top photo shows ample ashi that may be brought out over time or with further polishing, Which brings me to another option. Get a really big potato and stick the knife in it for a day or two. See what a good patina reveals.

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1 hour ago, Joshua States said:

3. Normalize that knife  and do HT again.

I'll add here, only try this one or 2 more times at most.  Dave Lisch, MS did a hamon polishing demo recently with a bowie that he had to HT 3 times in order to get the hamon activity he wanted, but in the process, he unexpectedly turned the bowie into a recurve.  He explained that during the multiple differential heat treating, while maintaining a soft spine, caused the edge steel to shrink enough, and pull the tip down.  His lesson was to re-do the quench if you're not happy with the hamon, but don't do it more than 2 or 3 times unless you're ok with changing the shape of the blade.

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5 minutes ago, billyO said:

I'll add here, only try this one or 2 more times at most.  Dave Lisch, MS did a hamon polishing demo recently with a bowie that he had to HT 3 times in order to get the hamon activity he wanted, but in the process, he unexpectedly turned the bowie into a recurve.  He explained that during the multiple differential heat treating, while maintaining a soft spine, caused the edge steel to shrink enough, and pull the tip down.  His lesson was to re-do the quench if you're not happy with the hamon, but don't do it more than 2 or 3 times unless you're ok with changing the shape of the blade.

That isn't going to be anywhere near as much of a problem on a kitchen knife cross section...

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5 minutes ago, jake cleland said:

That isn't going to be anywhere near as much of a problem on a kitchen knife cross section...

Good to know, thanks.

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I've been working on hamons for close to 20 years, and get the result I'm hoping for maybe 1 in 10. That looks perfectly fine to me - you're not going to get anything flashier with that steel. There looks to be plenty of activity that could be brought out, so you can use it for polishing an etching practice, but there's no mileage in going for a full art polish on a kitchen knife that's going to get used, in my opinion. If it were me, I'd give it a longish soak in ferric to get some contrast and just let the natural patina develop from there.

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Allright thanks for the additional feedback everyone. Maybe my expectations of the hamon were a bit too high. Im going to finish this one as it is and give it to the friend for who I'm making it. I'm curious to see how the patina wil develop over time. If I get some good pictures of it in the future I'll share it in this thread. 

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8 hours ago, jake cleland said:

I've been working on hamons for close to 20 years, and get the result I'm hoping for maybe 1 in 10. That looks perfectly fine to me - you're not going to get anything flashier with that steel. There looks to be plenty of activity that could be brought out, so you can use it for polishing an etching practice, but there's no mileage in going for a full art polish on a kitchen knife that's going to get used, in my opinion. If it were me, I'd give it a longish soak in ferric to get some contrast and just let the natural patina develop from there.

This

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