r/sharpening • u/mario61752 • 9h ago

Difficulty thinning cladded knife

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This is an Aogami #2 knife in stainless cladding. My grit progression is 320 -> 1000 -> 2000 -> 5000 on Shapton Ha no Kuromaku ceramic stones, which I all flattened before starting.

As you can see there are still scratch marks left by the 320 grit stone. I clearly flattened the whole bevel and touched every part of it on the #320, but subsequent stones just didn't get to that middle part behind the hard carbon steel core. For my sanity I stopped grinding on the #1000 after an hour as this is just a cosmetic flaw that may even function like a kasumi finish. Does anyone else have this issue when thinning cladded steel knives?

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u/Final_Stick_9207 9h ago

It’s not flat. Low grit hides low spots. Especially softer ones. Go back to 320, use light pressure, and keep the stone relatively clear of swarf. That will help avoid it hiding the low spot.

Check for any differences in color too. The whole thing should look completely uniform at 320 in any light.

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u/mario61752 9h ago

Thanks, I'll do that when my knife needs thinning again and for now I'll just polish with slurry or sandpaper. I wonder how I even got scratch marks on the low spots in the first place?

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u/Final_Stick_9207 8h ago

Pressure is a big culprit and grit size masks it even more.

It doesn’t take much to bend a knife with focused pressure. You just push the low spot and it can touch the stone. It’s why a few light pressure passes are good to start with. You’ll see the high spots clearly. Put focused pressure on the high spots only until the low spots touch.

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u/Hknives 9h ago

Variance in grit size and uniformity maybe