When I used my Naniwa 12000 to finish a blade that I was refreshing, it seemed that the blade actually lost sharpness after the 12000. I tested it after the Norton 8000 before moving on to the Naniwa 12000, and I could swear that the 12000 dulled the edge just a bit. It still shaves great after the 12000, but seems like it was sharper and smoother at the 8000 stage. This isn't the first time I've had this result. Although I have got the Naniwa to work wonders before, it seems very finicky to use.

Also, the Norton 8000 always feels smooth and silky, but the Naniwa has a more coarse feel when I pass the blade on it.

I don't soak either stone. I wet them before use.

Does the Naniwa need to be lapped, maybe? If so, what do you recommend that would freshen up the stone's surface without leaving abrasive stuck in the stone?

I use the Norton flattening stone for the Norton 8000, and haven't had problems with abrasive getting left behind. But something tells me the Naniwa might be different.

I also have one of the (now controversial) C12K/PHIG/Guangxi stones that performs at a level below the Norton 8000. I read somewhere before that they need considerable preparation before use, but I can't remember exactly what that involves.

Does anyone have advice on prepping and using the Naniwa 12000, or also the C12K?