Accidental Hamon Line?

johnnyjump

johnnyjump

Well-Known Member
I’m working on a series of five knives from the same pattern, and applying the same heat treat with each knife. The blades are 1095, and were brought up to 1475 degrees in the kiln and quenched horizontally in an electric turkey fryer and peanut oil that had been preheated to 120 degrees.The attached photo shows the two blades after etching in a 70/30 mix of ferric chloride and apple vinegar and handles fitted. The edge retention and hardening on both blades is very good. My theory is that the horizontal quench caused the blade to harden differently, with the thicker part showing the Hamon line. Any other ideas? Thanks.
 

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What thickness is the material? It looks like the peanut oil was fast enough to cool the thin sections of the knife but not the thick parts by the ricasso. How many blades did you quench before these 2? Maybe the oil was too warm to through harden.
 
Thickness is 5/32" at the spine. You'll notice the line starts at the thick part of the ricasso and ends at the beginning of the false edge where it's definitely thinner. I heat treated each blade separately, with a few hours in-between, while the electric fryer was set at a constant 120 degrees. It's possible the oil may have gotten hotter with each blade, but I believe I checked the temp of the oil with each blade.
 
Did you use a thermometer to check the temp of the oil or just the dial on the fryer? It looks like your oil wasn't fast enough to harden the thicker parts of the blade. If you used the dial I wouldn't trust it. If you used a thermometer you can test it's accuracy by making up a glass of ice water, and let it sit for 15 minutes. Your thermometer should read between 31 and 33 degrees.
 
I used a thermometer, but i’ll double check it for accuracy. Do you see any problem with the overall durability of the knives? Actually, I kind of like the lines as they add some character to the knives. Thanks for your input.
 
Check this info out and if you can't determine the answer for yourself.
http://www.cashenblades.com/steel/1095.html

If Kevin is available he will answer and he is going to give the straight up truth of it!! If I ever get to where I know half of what he knows, understands and has proven. Why hell I would feel like I had arrived!!

By the way I like the look of the knives! Not sure exactly the why of the lines but I don't think it hurt the knife. It just may not be up to it full potential!!
 
johnnyjump said:
I used a thermometer, but i’ll double check it for accuracy. Do you see any problem with the overall durability of the knives? Actually, I kind of like the lines as they add some character to the knives. Thanks for your input.
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No I don't think your performance is going to suffer. I used to use canola oil for quenching and had that happen a couple of times. I finally bought some parks 50. What a difference it made in the ease of quenching and getting repeatable results. It seems like a lot of money but the heat treat is the heart and soul of a knife. Not saying you're doing anything wrong but it definitely makes life easier.
 
[QUOTE=" My theory is that the horizontal quench caused the blade to harden differently, with the thicker part showing the Hamon line. Any other ideas? Thanks.[/QUOTE]
That's just 1095, its a shallow hardening steel. I get that sometimes too, really shows up on a sand blasted finish.
 
Of any of the natural oils, that I have done testing with, peanut oil has about the slowest cooling curve, it has a higher flash point and that is why it is preferred in these deep fry units, but it will not through harden 1095. Canola is faster but, as has been mentioned, something likes Parks#50 is fast, consistent and stable. When doing a horizontal quench I always try to hit the oil spine first to five the thicker blade portions a head start in keeping up with the edge in hardening effects. It can avoid reverse sori (curvature) and some of the hamon effects.
 
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johnnyjump said:
Thanks! I think I will need to invest in some Parks 50.
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That is a bullet that is hard to bite, be prepared for sticker shock but, in the end it is worth it and the quench oil will last a long time if you watch contaminates!! The Parks 50 takes all off the guess work out of that end! If you have a problem after going the Parks 50 route then it is somewhere else you screwed up. Been there and done that, too fat to wear the T-shirt, so to speak!!!:p:p
 
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When I said, contaminate, I was more referring to leaving it sitting in the rain! Believe it has been done! I remember some discussion about the furnace cement issue. However at the moment I can't remember what was said about it!! My thoughts would be anything that goes in the oil may break down it that is so, then overtime it would began to contaminate the quench oil.

It is kind of like this, if you have ever noticed an asphalt parking lot. Where the vehicles park you will begin to notice that the asphalt is deteriorating. Asphalt is bound together by asphalt cement, a product of crude oil. However where the oil leaks out of a vehicle or the occasional overflow or leak of the antifreeze gets on it begins to break down the asphalt.

The same thing may be happening with the Parks 50. I will dig a bit more and if I can't answer that I know someone who probably will!! Either way I will get back to you on how much of a problem it might be!!

EDIT:
OK I found this, http://www.getottenassociates.com/pdf_files/Quenchant Fundamentals Quench Oil.pdf

It is a bit technical but, not that hard to understand and it was written up by one of those engineers in the white coats I would guess. However it does deal with contamination and where that may come from and how to deal with the contamination!!

On the flip side of this I have sent a message to one who should know and when I hear back I will share that info as well!!
 
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Moisture and shop dust are the worst contaminants. There could be some elements of cement or clay that may have an effect over time, but for the most part I believe it is insoluble in the oil, and I have not noted a significant difference. There will be chunks that will inevitably fall off and fall to the bottom of the quench tank, these should not be allowed to accumulate since agitation could break them up small enough to become a suspension over time. Simply drain off the oil to clean out the bottom before putting it back into the clean quench tank.
 
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C Craft said:
On the flip side of this I have sent a message to one who should know and when I hear back I will share that info as well!!
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So there you go. When you need a drink, you go to the well!!


Kevin R. Cashen said:
Moisture and shop dust are the worst contaminants. There could be some elements of cement or clay that may have an effect over time, but for the most part I believe it is insoluble in the oil, and I have not noted a significant difference. There will be chunks that will inevitably fall off and fall to the bottom of the quench tank, these should not be allowed to accumulate since agitation could break them up small enough to become a suspension over time. Simply drain off the oil to clean out eh bottom before putting it back into the clean quench tank.
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