How to remove scratches from a new Makoto Kurosaki

[JoseMartinLopez]

I bought a "used" Makoto Kurosaki 270mm sujihiki to try and compare to a Suisin Inox Honyaki 270mm gyuto, Raicho No Ren 270mm sujihiki, and some other very thin slicers. It was supposed to be practically new and just tested by the previous owner.

However, it seems the previous owner wiped it off several times with the dark green side of a normal Scotch Brite. There are long superficial scratches that are parallel to the spine, from the tip all the way to the edge, then curving up to the tang. It's almost like someone deliberately wiped the blade from edge to heel with long strokes and a lot of pressure, creating long, consistent scratches that run the length of the entire blade (and it's a 270mm sujihiki).

They are cosmetic but I keep thinking "poor knife" every time I see it. The knife was hardly used but not cared for. No kind of use could have created the scratches I am talking about. (The knife was poorly packed when it was sent to me, sent in only the knife box wrapped with a single layer of bubble wrap and placed in a polybag. But the scratches were definitely not from shipping.)

Makoto Kurosaki knives have a smooth matte finish. Is there some easy way to remove the scratches I describe? Metal polish, sandpaper, send it to a store with a buffing wheel...?

[Chappychap]

Pictures? I'll defer to others more experienced than I but FWIW I managed to reduce scratches on a new gyuto tip sufficiently with high grit sandpaper. Wasn't perfect but enough to make it so that it didn't catch my after.

[Jeff B]

You'll never reproduce the factory finish. You can start with a high grit sandpaper(~1k) to remove the scratches and if it isn't course enough drop down in grit until it is. You can progress back up from there until you get the finish you like. You'll have to do the entire blade to get a uniform look.
You can also polish it with natural finger stones to polish and remove the scratches.

[ronnie_suburban]

You'll never reproduce the factory finish. You can start with a high grit sandpaper(~1k) to remove the scratches and if it isn't course enough drop down in grit until it is. You can progress back up from there until you get the finish you like. You'll have to do the entire blade to get a uniform look.
You can also polish it with natural finger stones to polish and remove the scratches.

Just curious . . . dry or wet on the sandpaper?

[Jeff B]

You'll never reproduce the factory finish. You can start with a high grit sandpaper(~1k) to remove the scratches and if it isn't course enough drop down in grit until it is. You can progress back up from there until you get the finish you like. You'll have to do the entire blade to get a uniform look.
You can also polish it with natural finger stones to polish and remove the scratches.

Just curious . . . dry or wet on the sandpaper?

I use wet but either will work. It's more preference than anything like so many other things...

[branwell]

Chances are this wont work but.......If the blade has a scratch pattern from its manufacture, something you might try is to use a "rust eraser" running in the same direction as the manufactures scratch pattern. Try a medium or a fine.

[ken123]

Pics would definitely help. You can closely duplicate the original finish with the right tools or even exceed it. I just recently did this on a Nubatama knife that was originally done by a sword polisher. Send me a message for more details. Most sandpaper finishes are too rough.
Ken

[ken123]

This example uses diamond bars on a variable speed buffer. Very controlled system for precise scratch removal.

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Ken

[ken123]

This uses a more powerful buffer.

[michael1778]

This uses a more powerful buffer.

This is what came to mind!

[Nochop!]

You'll have to recreate an entirely new scratch pattern. I would start around 220 grit. Progress to 320, 400, 600, 800 or so. Having access to belt grinders, I would finish with either cork or a fine scotch bright. It's impossible to create that hazy blasted matte finish. Some would use finger stones. I have no real experience with that, though.

[Jeff B]

This uses a more powerful buffer.

Did you video the time you impaled your foot?

[ken123]

"Did you video the time you impaled your foot?".

No. Too much bleeding to use a camera. However if you want to volunteer....

My foot is doing well. Thanks for your concern.

Ken

[ken123]

The diamond bars come in grits from 80 microns to tenth microns. I do have 200 and 300 microns but rarely use these, so yes you need to use a sequence of grits. Sometimes I use other compounds in a sequence with the diamond bars depending on the scratch depth. (Separate topic)

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Ken

[PaulME]

Change wheel for each compound - right
You can get to mirror ish finishes with wet sanding paper, around 2000 grit, can go higher. The real issue with polishing like this is that actual scratches from wiping etc will show up so I have never bothered on knives.

[ronnie_suburban]

I'm curious. Are scratches like these merely a cosmetic issue or do they affect performance and durability?

[ken123]

"Change wheel for each compound - right"
Yes. Similar to other sharpening stones. In this case you can go WAY past 2k grit to 160k grit if you wish. I often find 2 micron bars (8k) more than adequate
Ken

[ken123]

I'm curious. Are scratches like these merely a cosmetic issue or do they affect performance and durability?

I think they do. I often use these for cosmetic work including removing patinas and rust but for rough scratches and preparing kasumi finishes, I go for diamond bars. For real deep scratches I use other compounds and wheels ( a longer topic).
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Ken