Yikes! Unsharpenable Steel? / Beware of cheap Kanna

[Luke Dupont]

Hi guys.

So, I've had fairly good experiences with cheap Japanese tools in the past. As such, I picked up a 2000yen ($20) kanna at Tokyu Hands the other day. And, all seemed well until I decided to flatten the back and sharpen it...

The blade is apparently of laminated construction, but the steel on the back is insanely hard -- so much so that I suspect it wasn't meant to be sharpened(!).

There was a bit of a buffed bevel on the back which was almost impossible to get out, despite being very shallow. I ground and ground and ground, and wound up wearing out my new 150 grit diamond plate on the sides. I finally got it more or less flat, but it left the blade all chipped.

So, I decided to try to remove the chips by grinding down the bevel side. I was at it for hours on my coarsest synthetic stones. My coarse diamond stone was the only one that seemed to really cut the hard steel, but seemed to just further the chipping, and even it was pretty slow. My India stone and all of my other synthetic stones didn't seem to cut anything other than the soft iron lamination effectively. No matter how long I went, no apparent progress was made in removing the chips.

I've never seen steel anywhere near this hard. I know that some Japanese steels can be extremely hard, but surely not as hard as Al. Oxide or Si. Ox? Is this some cheap throw away tool not made to be sharpened, or are some Japanese steels simply so hard as to make repair work when you chip them extremely difficult? My other cheap Japanese tools are extremely easy to sharpen whilst still being on the hard side.

I guess I should stick to better quality Kanna in the future. There might be some good cheap ones out there, but it seems to be hit or miss.

Lesson learned? Whatever money I thought I saved by buying a cheap tool, was not well spent. I ended up with a worn out diamond plate, 4 hours of frustration, and a dull, unsharpenable tool. Either that, or there's a whole other world of sharpening crazy hard steels that I don't know about and probably don't care to be a part of...