Selective tempering, achieving a hamon

[RainsFire]

so, I have attempted at making a temper line 3-4times now with no success. I use 1050 steel, and satanite. I leave the steel coarsly finised at about 100grit.. I rinse/scrub it with water and a rag, then I wipe it in windex with a clean paper towel.. so the cement does not come off..
I heat it up to above critical.. (almost orange) and quench in a trough of water edge first with a few dunks. I check for straightness (perfectly straight because I normalized so cool!!) and quench it again to completely cool it.
I chip off excess satanite carefully so as not to shatter the hardened blade.. and tempered it at a blue tapering to straw color from spine to blade.
I then polish with a coarse stone, tapering down through finer and finer stones/papers.. I usually get to about 400, and realize there's no hamon.. so I etch it in vinegar for about 15min.. and still no hamon..
what the heck?
please help me guy's.. thanks.

[EdCaffreyMS]

It could be several things. From what you mentioned, my first thought is that the tempering to blue is destroying the temper line. The line itself is a delineation in the grain structure. When you temper the whole blade to blue, your likely taking away that abrupt change in the grain which shows up as the temper line. The water might be an issue too. My opinion is that any carbon or tool steel should be quenched in oil. In this case a very light oil like mineral oil or peanut oil is called for. With 1050 you would only achieve an Rc hardness of around 55-57 as quenched, and in theory you should not have to temper, maybe just a stress relieve at 350F. If you try it, and an edge does crack, that is usually telling you that you need to sand to a finer grit prior to quenching. I usually got to at least 120 grit to prevent stress risers from forming along the scratch/grinding marks.

The whole idea behind "clay hardening" is that the area covered with clay never gets hardened, while the exposed edge does, and the temper line that shows in the end is nothing more than the transition zone where the blade goes from hard to soft.
You can can achieve the same thing by just edge quenching the blade, rather than quenching the whole thing. I do it on most using knives I make.

Try just stress relieving the blade after quenching at 350F for two hours and see if that makes any difference. When I clay quench, I can normally see the temper line as soon as I knock off the clay.

[RainsFire]

Thats the thing, I can see the line just fine its just, after doing all the finish work it's gone.. I dont just mean where there is clay residue vs where there is not, its an actual line in the metal (hamon) but it polishes out lol..

you're probably right about the tempering part, I dont know what I was thinking..
Thanks!

[brucegodlesky]

Try using a stronger etch.
And sometimes varying the etch will give a better look. By that I mean, etch in vinegar, then a quick etch in FeCl. bruce

[Lamey Knives]

EDITED TO ADD: Can you post pics?? If the hamon is there when you start polishing it shouldnt go away... as suggested try a stronger etch and less aggressive polish media.

Are you testing the blade for hardness after quinch? Your either jumping the clay and hardening the entire blade or your not getting a conversion at all and the blade simply isnt hardening.

With great respect to Ed, tempering to blue/tapering to straw should have no effect on the hamon IF it was there to begin with.

You would be well served to have some sort of pyrometer to accurately check your tempature, and when using clay let the blade soak for enough time for the clay to pick up color and go from "black" to "orange" along with the blade. Keep in mind when doing this you will generally jump the clay line some, but still achieve a very nice and active hamon pending on your clay thickness and application.

Another thing to consider would be steel type, I get much better results with 1095 over anything else ive tried. W2 is a close second but reacts much differently to clay thickness than does the 1095.

I never go over 400 grit when finishing, just dont have the time. Here are a few photos of hamons using the following method-
Soak temps. at 1450-1500 (at 1450 you get more of a direct transition where the clay is applied, at 1500 you get a transition line that has jumped the clay a bit, and get more overall "activity" in my experience).

Make sure your clay is applied and sticks well.
heat to and soak (until the clay also pick up color) at 1450-1500
quinch in proper quinchant, Parks 50, Texaco Tuff quinch etc.
remove excess clay, straighten blade QUICKLY while still hot (if needed)
temper @ your favorite temp.
take to 400 grit
etch with ferric chloride mix
polish with your favorite media

Here are a few pics using the above method-

[Tyler Murch]

1050 is a very shallow hardening steel. Each time the steel is normalized, the grain becomes finer, and the finer the grain is, the shallower hardening the steel is. Perhaps you are getting only a very very shallow hardening and are taking it off from polishing. Try one normalization, maybe two. Three is overkill. Also, when going into the quench, go at the lowest temp you can manage while still being fully austenized. Less heat going into the quench means that less heat must be removed in the quench.... 1050 must be quenched very quickly in order to harden.

[kbaknife]

Phenominal work, Matt.
I'm a BIG fan of your hamon activity.
What are your post-forging techniques?
1 normalize?
2?
Any sub-critical anneal on those?
Full finish on the blades prior to quench?
Satanite?
Parks #50 @ 100 degrees or so?

[ApprenticeMan]

WELCOME Matt! Gorgeous work those hamon are to die for!

[RainsFire]

Wow, Lamey those are beautiful!
amazing!!

I normalized on my last one twice, the edge was hardened but I did not check the spine. (whoops..) there will probably be a difference even now after the tempering right? I'll go out and give it a polish to see whats going on.
pictures up possibly tonight at 400grit and etched whether there is a hamon or not..

[RainsFire]

ugh, just gave it a quick polish by hand up to 400grit, and no hamon not even a hint of one. I think the whole blade was hardened because there is no difference between spine/cutting edge as far as I can tell for hardness.
can I bring it up to critical a few times and recoat? or should I sand it back down with a coarse grit?