how i achieve a Hamon

[KHalverson]

here is a knife blank forged from a piece of recycled buzz saw blade.
I have made several knives from this steel and have done some testing to make sure my methods are sound with this steel.
your mileage may vary with what ever steel you choose to use.
here the blade is shaped and the bevels are rough set.



next I sand longways to a nice 120 grit finish and leave a radius on the cutting edge to reduce stress risers.
the edge is ground to about .050 thick.


next i apply my refractory cement in the desired area for the hamon.
i also add just a tiny amount to the cutting edge just to help stack the deck against cracking.



the cement is only applied .060 to .090 thick.




here the canola oil is being preheated with a hot piece of rebar.
the oil only needs to be warmed to maybe 100degrees or slightly higher.



here i am speed drying the refractory cement .



next the knife is in the forge slowly coming up to critical temp.

[KHalverson]

here we are .
up to temp and ready to quench.

[DC]

You do both sides, right? Does the pattern have to match side to side for any weird reason?

[KHalverson]

You do both sides, right? Does the pattern have to match side to side for any weird reason?

Correct.
I have found that trying to keep it even. Seems to keep the blade straighter.

[ssgtchad]

Does your clay/refractory puff up while being heated?

[KHalverson]

Does your clay/refractory puff up while being heated?

yes.
i had some imperial brand that didnt.
it doesnt seem to effect things though.
i have let it air dry over night and it will still puff up.

[KHalverson]

next I quench the blade in a vertical position.
I move the blade back and forward to help speed cooling.
never stir the oil  from side to side with the hot blade .
this can cause warping.



here it the blade coming out of quench.
it is not uncommon for some of the refractory to fall off as the blade cools.




here the blade is cool and with most of the refractory removed with a putty knife.



i then use dish soap a small wire brush to scrub off the residual oil and refractory cement.

[KHalverson]

after degreasing I like to clean the blade up with 120 grit paper .
then off to temper.



here is the blade after 2 hours @ 375F .
if you look the hard portion of the blade is a slightly different color than the softer steel.
this tells me we have a hamon of some sort.

[KHalverson]

next step is to sand to a 320 grit.thats just my personal preference you can go higher if you so choose.



here we are @ 320 the little lightening bolt looking thing is the hamon being exposed by sanding.




next we get out the vinagar and insulated coffee cup.
this will be used to etch the blade giving it a patina while exposing the hamon.



next i heat the vinagar to just boiling and add it to the coffee cup with the knife already in it.
i use a piece of wire for a handle.
the vinagar will start to fizz.
dont be alarmed its just doing its job etching.

[Pappy]

Thanks Kevin, how long do you leave it in the vinegar ? I did the one you talked me through about the same but didn't put anything on the edge as you did, is that a real problem ? also didn't heat the oil, I use burnt motor oil. That blade looks really nice, just beautiful.
  Pappy

[KHalverson]

pappy

 i'd ditch the used motor oil.
i used it many years ago when i got started.
canola works so much better.
warming the oil up speeds the quench.
most shallow hardening steel like whats in files and saw blade steel require a fast quench to harden properly.
thats why they get so hard in water or brine but for a larger piece of steel like a knife its too fast and cracks them.

the tiny amount of clay on the cutting edge is just a little insurance.

[KHalverson]

here is the blade after 4 minutes in the vinegar.
it takes about a minute for the hot vinegar to start etching well so this is about a 3 minute etch.



next I rub out the blade with ultra fine steel wool and tooth paste.







the blade can also be polished further by rubbing out with pummice or buffing.
i know there are other ways to do this but this is how i do it.
i hope it helps some people.
Kevin

[DC]

That turned out nice. What happens if you leave it in the vinegar longer?

[KHalverson]

That turned out nice. What happens if you leave it in the vinegar longer?

.

Deeper etch.
Pits in the steel.

[osage outlaw]

Very nice!   Thank you for posting this