Black oxidation (?) spot on A2?

[y53p]

Recently bought this knife in A2, had a black stain on it, which the previous owner probably tried to remove, as the area around it is clearer than the rest. I tried flitz and it did nothing. I don’t wanna resort to sand paper as that would ruin the overall grind of this knife, which was pretty expensive to begin with. Any chemical or substance that will get rid of it without excessively furthering some kind of mirror effect on the targeted area?


You can see it in the picture, in the center top.

 

[Obsessed with Edges]

If it were just black oxide on the surface, Flitz should've cleaned that up. Since it didn't affect it, the dark spot might be microscopic pitting of the steel left after (possibly) a rust spot was previously cleaned up. Pitting will appear dark against a bright & shiny backdrop on the blade. If it is pitting, then sanding/grinding would be the only way to remove it completely. Any chemical means used to remove rust or oxide may itself cause additional oxidation and/or pitting of the steel, so I'd avoid that.

If you're not wanting to alter the overall finish of the blade, I'd leave it be. Alternatively, some very light mid-high grit sanding done in very small measure over some time might eventually diminish or remove the pitting (if so), without significantly altering the grind profile of the blade. Choosing the right grit to emulate the overall satin finish on the blade is key, unless you're willing to use the same grit on the blade overall, to blend it all in. Most brushed satin finishes on factory blades can be emulated by anything from ~220-600/800 grit in SiC sandpaper. Anything much higher in grit will start to look more polished against the satin backdrop.

Again, having said the above, I'd likely leave it alone if it were mine. Or you might inquire about sending it back to the maker for a refinishing job, if they offer that service (likely for a fee).

 

[Tjstampa]

I would have to agree with obsessed with edges but would add that you can get some higher micron diamond laping compoud on a microfiber cloth to sand the area out. I used an 18 micron paste given to me from a jeweler. It was fast cutting but even that high a micron left my blade shineyer than i wanted.

 

[y53p]

I would have to agree with obsessed with edges but would add that you can get some higher micron diamond laping compoud on a microfiber cloth to sand the area out. I used an 18 micron paste given to me from a jeweler. It was fast cutting but even that high a micron left my blade shineyer than i wanted.

Probably gonna send it back to the maker or to a local knifesmith. Don’t wanna further ruin this knife’s finish. Thanks for the advice.