Sharpening Ceramic Knives?

Hi, I accidentally scored a set of five ceramic knives from a thrift shop ($1.00). The brand was Keramikos Kitchen out of Vancouver. The company has gone out of business. So much for the lifetime sharpening and replacement guarantee! Data is hard to come by, but there's reason to believe people paid a lot of money for these.

Anybody have experience sharpening ceramic knives? I looked at all the web tutorials and I have diamond stones, but anecdotes based of field experience would be really helpful.

I went through this with a cryogenically tempered knife. The trick is to not use gritty/coarse sharpeners. You want to take off a fine layer, not chip/scrape like you get with hard diamond or sandpaper.

This guy used a high RPM MDF stropping wheel with some kind of buffing compound.




I think the reason for this is ceramic is hard but brittle so it chips when using diamond or stone on it so the edge doesn't last long. Whereas steel will have material rolled off in layers in a more forgiving way. Ceramic needs very thin layers (~3 microns) removed like peeling bark or knapping obsidian. That's my understanding at least.

I just use diamond hones. They have worked fine for me with no special consideration that I can recall.

Normal sharpening methods will work but you won't get anywhere near a factory edge that lasts very long. The factories use high-rpm wheels that get the edge white hot when sharpening.

Interesting -- the video guy had to go to a 3 micron and then 1 micron diamond paste to get any results. I do like the MDF power hone idea though -- I just scrounged a bunch of commercial density stuff.

I wonder if some ceramics are hard enough to abrade other ceramics.

Aha! I  hit the mother lode of information (and sharpening nerd delight).

This guy tried various techniques and equipment on ceramic blades (cheap and expensive) and documented the results using a scanning electron microscope (!).

https://scienceofsharp.com/2018/02/24/ceramic-blades/

Summary: Best result (affordable) was with Mothers Mag polish on a hanging denim strop. Better than diamond. Go figure!