what is this staining?

[paranoid123]

I purchased this Tsukiji Masamoto Honesuki described to be SK carbon steel. It has this staining on the both faces of the blade. Looks like a water stain, but won't wash off with soap and water, I can't really take it off with a rust eraser. Is it oxidation or patina? What is the best way to clean it off without scratching it? I do use the knife so I don't need to baby it.

 

[M1k3]

Hard to see in the picture. But you mentioned it being SK steel, which is not stainless.

 

[kayman67]

Patina should be an easy job for a rust eraser.

Try some auto grade polishing compound and see what happens.

 

[inferno]

I purchased this Tsukiji Masamoto Honesuki described to be SK carbon steel. It has this staining on the both faces of the blade. Looks like a water stain, but won't wash off with soap and water, I can't really take it off with a rust eraser. Is it oxidation or patina? What is the best way to clean it off without scratching it? I do use the knife so I don't need to baby it.


View attachment 64225

its completely impossible to see anything from your picher unfortunately. however either its sk5 clad in stainless or simply unclad sk5 or lower sk series steel, which is like 1095 carbon steel, or so.

either way. if you have a stain that you cant remove by scrubbing or rust eraser or similar you will have to resort to more effective abrasives. such as:
(in increasing order of fun)
metal polishes for cookware and similar pastes such as green chromium oxide
cbn/diamond/aluminum oxide/silicon carbide pastes/sprays
sandpaper
sharpening stones
belt grinders
angle grinder (this is my favorite, i used flap discs for mine, cubitrons)

i have had weird stains on steel too. i once just let some pasta sauce dry up on a polished stainless clad akifusa blade for a week or so. and now it has a stain there that simply cant be removed without scratching/refinishing the blade. you know what i did about that?? nothing.

 

[Furminati]

It’s carbon steel. That’s patina setting in. I’d let it build personally, it will be more stable with use. If you clean it off it will just keep happening. If you want the patina stripped , bar keepers friend works great