how do you get blade surface look darker?

H

hammerfall

Joined
Oct 2, 2010
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221
how do you make a mirrior polished blade look darker? for example like those japanese blade with darkened spine and white edge.

i had tried 5%HNO3(room temperature), 20%FeCl3(60°C), and some fresh lemon juice. they did darken the spine but once mirriored polished it go back to the original metal color.

so how do you keep the mirrior finish with darkened color? any suggestions are welcome.
 
I think they only get that as a result of coating the spine of the blade with clay to differentially harden the blade. And what you may be referring to is a hamon.

Someone please correct me if I am wrong.
 
There are several methods of darkening a blade.
Parkerizing
Hot Bluing
Cold Bluing
Etching

They must be applied after the polishing is done, as they would be removed if the blade is re-polished. Some folks give the surface a light buffing with 4-0 steel to brightens the blade up a bit without removing the darkness. I use a 4000 grit polishing paper ( 3M pink) to brighten the surface.
 
I polish the blade somewhat, etch it in dilute FeCl and then boil it in a strong baking soda solution to set the oxide, water alcohol rinse then oil it.
that is how I get these blacks
_DSC5101small.jpg


1095-nickel-dag1.jpg


The steel in both cases was Aldo's 1095 with nickel for the white

_DSC5118small.jpg


this one is cable

-Page
 
Thanks for the boiling tip Page. How much more resistant does it make it? will it stand up to regular use?
 
Hammerfall, on many Japanese swords the blade is brought up manually to a very high stone polish, then one of the treatments they use is "nugui" to darken the back area of the blade. This is finely ground and filtered iron oxide, I've not tried it yet but want to.

You want to mirror polish first, darken with something that does not affect the quality of the surface, and then as Stacy says, follow with a very fine abrasive to bring back some sheen. Some of the metal polishes such as Flitz may help re-shine while retaining darkness as well.
 
Ummmm what type of steel are you using? That pretty "dark color" in a Japanese style blade is due to either the difference in etching resistance in the hard and softer states of metal OR the difference in etching resistance in the hard and soft states of the san mai lamination.

If the entire carbon steel blade is hardened you're not going to show much difference in "darkening" after an etch because the entire blade will react to the etchant in the same manner.

Stainless steels I have no idea.

Recommend you study up on "differentially hardened" blades, hamons, temperlines, differentially tempered blades.... can't think of what else. There's a guy on youtube that has some good videos on semi-traditional sword polishing.
 
Mirror polish w a darkened color is easy to do, I used to do it To pistols all the time when I was a pistol smith.
First mirror polish, degrease, next hot blue and your done.
Cw
 
thank you every one, i will try all these methods.

and yes, i did differential hardened blade. i used a type of chinese version of carbon steel similar to aisi W2. normalize, anneal, then differential hardened it. etching did make a lighter edge and darker spine, but once mirrior polished the color difference went away.

and i want a finish looks like this one

darkened%20blade.png


darkened%20spine.png


those pictures are downloaded from http://www.sword-art.com/web/33/HTML/20080130003.htm
 
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