Strange Splintering Effect in Hamon

Jesse WW

Jesse WW

Joined
Jul 8, 2017
Messages
71
Can somebody explain to me what the cause of this may be? I just finished up polishing this blade and the Harmon seems to have this somewhat exploding/splintering effect going on. Everywhere else there are patterns that i would describe as palm prints! I cant wipe them off no-matter what i do though. I’m curious if anybody here would have any idea? Steel is oil quenched 1075.

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Excuse the bad polishing btw, it still needs some touching-up

sCc3kUK

2vtvprs

AVkimQN
 
Those pictures are not good enough to show what the problem may be. All I see is scratches on the surface, and under that perhaps some decarb scratches in the skin of the steel. I see that happen sometimes when blades are quenched with a rough surface finish, the bottom of the rough scratches will decarb deeper than the surrounding steel and so will show up as dark scratch like lines on the surface although the steel is physically smooth. All you can do is grind deeper to get rid of that. There may be alloy banding but it's hard to distinguish from your photos.
 
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No disk sanding (i should get one though).
Before quench i ground (grinded?) to 120. After quench i ground from 120 to 240. I didn't grind a lot though - only enough to clean up the blade (maybe 0.3mm of steel removed, maybe a little more). After that was sanded by hand; so 180, 240, 320, 400, 600, 800, 1500, then 2000.

Ill try to get some better pics of the blade when i get the chance. But none of this seemed to happen to any other blades that i treated in the same manner.

They definitely are not scratches. I have marked in red what i am referring to just in case there is any misunderstanding as to what I'm talking about:

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I ask because I'm not sure whether to think if this is a unique quality of the Hamon, or if its something that definitely shouldn't be there. I have only made a small handful of knives so my experience runs a little thin. I have never seen anything mentioned online referring to this kind of activity in a Hamon. Salem mentioned decarb scratches, but I'm not sure what these look like.

Any ideas?
 
It looks like the blade was sanded too quickly from 120, 220, and 400. I can’t see it looking finer than that. You might have gone up in grits, but you didn’t get the previous grits marks out first.
 
Willie71 said:
It looks like the blade was sanded too quickly from 120, 220, and 400. I can’t see it looking finer than that. You might have gone up in grits, but you didn’t get the previous grits marks out first.
Click to expand...

From looking at the image i can see how the lines i marked in red in the previous post can be interpreted as lower grits that have been left over. They definitely are not a leftover grit though, as they don't reflect light like a typical scratch would and they are 100% smooth.

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I will have to re-sand the blade anyway as i have missed some some of the lower grits, but i am entirely curtain i have removed absolutely everything lower than 600-800 grit. This pic helps to show that the perpendicular lines i am referring to aren't lower grits leftover from the belt.

edit: Is there any possibility that it can be micro-cracking?
 
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In one pic the hamon runs off the edge.

If I had a dollar for every time someone was sure they went through the decarb later, but realized they didn’t, I’d be rich.
 
Willie71 said:
In one pic the hamon runs off the edge.

If I had a dollar for every time someone was sure they went through the decarb later, but realized they didn’t, I’d be rich.
Click to expand...
So it will need a regrind you reckon? How much steel typically needs to be removed to remove all the decarb? It looked pretty clean when i ground it before! What can i do in order to ensure i remove absolutely all of the decarb while grinding?

Josh Rider said:
What did you etch with and go over your process after hand-sanding.
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Pretty much just one coat of fc with a cotton pad. After that i gave it a good Flitz. Before the fc i tried the lemon juice technique but wasn't really getting anywhere with it. The lemon juice just ended up leaving big blotchy streaks in the steel and didn't have any affect on the Hamon. I have a feeling i may have used the wrong kind of lemon juice though.
 
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It is easy to confuse deep pre-HT scratches with the decarb left in them. You may have sanded .3mm off the surface to reach the bottom of the scratch, but there is still a bit of decarb in the surface where that bottom used to be. At this point the surface may be scratch free, but the metal is two types. Go back to 220 grit and take off another .1mm and see if the scratches disappear.

I get this effect sometimes when I did a lot of hogging with a low grit belt and didn't get all the deep scratches out when I went to 120 before HT.
 
This is what Willie71 Willie71 was talking about. Your Hamon goes right off the edge, so that entire section of edge will be soft. I highlighted your actual Hamon in red. All of that other activity going on is probably decarb.

You will have to requench your blade unfortunately.

ea83YjZ.jpg
 
I have little Hamon experience but a lot with Decarb... that is decarb. Pre HT sanding is not just important from a stress riser standpoint but the more uniform the surface is, the more uniform the layer of decarb will be. You are seeing the remains of the "Colorado River", left from the "Grand Canyon" you heat treated.
 
Jesse WW said:
No disk sanding (i should get one though).
Before quench i ground (grinded?) to 120. After quench i ground from 120 to 240. I didn't grind a lot though - only enough to clean up the blade (maybe 0.3mm of steel removed, maybe a little more). After that was sanded by hand; so 180, 240, 320, 400, 600, 800, 1500, then 2000.

Ill try to get some better pics of the blade when i get the chance. But none of this seemed to happen to any other blades that i treated in the same manner.

They definitely are not scratches. I have marked in red what i am referring to just in case there is any misunderstanding as to what I'm talking about:

SiM9BgU.jpg


0g01BeQ.jpg


I ask because I'm not sure whether to think if this is a unique quality of the Hamon, or if its something that definitely shouldn't be there. I have only made a small handful of knives so my experience runs a little thin. I have never seen anything mentioned online referring to this kind of activity in a Hamon. Salem mentioned decarb scratches, but I'm not sure what these look like.

Any ideas?
Click to expand...
I see what you are talking about and get that sometimes myself. It's just a cool thing that shows sometimes in etched blades. Some call it a wutz effect.
 
The hamon is real close to the edge out near the tip, but not sure what you got at the other end? Only shows on one side. Better pics without all the glare might help.
 
Heh, the part you marked out S.Alexander is just the reflection of the side of my head and the top of my shoulder, which is funny because even i had to look twice myself when i uploaded the image - you can just make out my red iphone in the middle of the blade. Comes to show how deceptive photos can be when trying to show off the Hamon! :rolleyes:

Don Hanson III said:
I see what you are talking about and get that sometimes myself. It's just a cool thing that shows sometimes in etched blades. Some call it a wutz effect.
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Interesting! I will need to find a way to make it stand out more because it does look cool. Looks kind of like trees on a mountain, or fur even. I just wasn't sure if it was something i should be suspicious about.

Don Hanson III said:
The hamon is real close to the edge out near the tip, but not sure what you got at the other end? Only shows on one side. Better pics without all the glare might help.
Click to expand...
The stuff happening around the plunge is just my reflection as i pointed out.
Unfortunately as for the tip, that is not a reflection and is actually part of the hamon... sort of. I'm not really happy with how that part turned out.



Seriously, i think its best i get some better photos because we all seem to be interpreting the images differently.:confused: I am unable to at this very moment unfortunately, so i will post back when i get the chance.

Thank you all for your input btw.
 
Jesse WW said:
Heh, the part you marked out S.Alexander is just the reflection of the side of my head and the top of my shoulder, which is funny because even i had to look twice myself when i uploaded the image - you can just make out my red iphone in the middle of the blade. Comes to show how deceptive photos can be when trying to show off the Hamon! :rolleyes:
Click to expand...

Haha oops. I stand corrected.
 
It sure looks like a beautiful knife!
You’ll probably have to etch/polish several times to see every bit of activity in the hamon.
 
I am happy to see i am not the only one being painfully aware of the decarburation effects.
I see to often comments about decarburation being just barely a surface feature; it is, but to really get a grasp on its extent i have had to wait till my Rockwell came in. Gross decarb could be visually spotted, but if you take a sample and have hrc reading while sanding you will find that the target hardness is deeper down than what you can think just by looking at the white haze being sanded away.
 
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