1075 hamon

So, I actually had the same thing going on with 1084 that I got from aldo. I ground through the decarb, hand sanded changing directions up to 1500 grit, but still had streaking in my hamon. I just got some 1075 thinking that it may be better, still waiting on that order. But that is disheartening. Not to hijack the thread, but if anyone has any recommendations here.. Feel free to DM -I use a forge to HT
 
Because of 1084's manganese content, hamons won't have the character that other lower alloy steels allow...you can get a line, but for the majority of us that's all we're gonna get.
 
I’ve gotten this with aldo’s 1075 a bunch. Been using it for a few years and it’s been a consistent thing. For a long time I thought it was due to my errors, but a while back I re ground a few test blades and made a new tanto. Still have those streaks in/above/below the white of the hamon. I’ve just accepted it as part of the steel. Didn’t have this issue at all with a white steel #2 blade and a 26c3 blade.

Also I got it from both forged and stock removal blades. The newer tanto I made started as 1/4” stock and I forged it down to 1/8” as practice before making the blade. Still had those streaks. It also frustrates me because I hate the look of them, gives the hamon a “lazy” look (at least to me) as if grit progression wasn’t done properly.

I love the activity I get from his 1075 but it bums me out when I can see that there’s more detail/activity being distorted/covered up by those streaks. From now on when I know I’m going to go for a higher finish on a hamon I’ll just use 26c3. but if I need more toughness in a blade and only going to the 400-800 grit range then I won’t worry about it and stick with his 1075.

I can post pictures up later if needed as examples

Kevin
 
polish avenger said:
What is your procedure for cleaning the blade before placing it in the etchant? I know that I get affects like that sometimes that go away when I re-sand and re-etch.
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I use dawn dish soap, hot water and a toothbrush and i scrub it really good. I dry it off with a clean paper towel and right into my etchant, which I believe is a 4-1 or 5-1 ferric solution. I have gone back to the grinder, I have resanded, refinished, recleaned and re-etched so many times. It's something in the steel, I am sure of that. There are quite a few posts about this and it seems like its mostly happening with steel from NJSB. I haven't seen any consensus on the cause or the solution. Most responses are similar to yours- suggestions around etching or finishing- which is not the issue.
 
One issue with a knife that was hardened for a hamon is that you are skirting around a full hardening. Various structures are created that may or may not look good. Added to that is the use of a steel with alloying that works against a hamon (like 1084). The final issues may be in using less than perfect hardening temperatures to get a better hamon.
Some of the problem may be in the steel manufacturing at the foundry, and some may be in the HT procedures you did.

One way to decide which is the issue is to sand the blade clean, do a full thermal cycling to dissolve carbides and refine the grain, and fully harden with a standard quench in an appropriate oil (I use Park's #50 for 1084). Do a double temper at 400°F and clean off to 400 grit. Etch and clean up with steel wool. This should give you a look at the steel in a normal hardened state. If there are still blotches and streaks in the places they were before, it is most likely the steel. If the surface looks good and clean, it was most likely the hamon quench and procedures.
 
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