Sharpening Santoku knives for home use

Is it the power of word-of-mouth among housewives? Sharpening and repair requests are flooding in one after another. Many come with a time request: ‘Please have it done by evening (for dinner)!’—so I’m working hard, haha.

And then, it happened… A Santoku knife that I could already tell would be tough to sharpen! Even before the customer pulled it out of the bag, I could just feel it, like, ‘Oh, here we go!’ Sure enough, out came a stainless steel one-piece knife. ‘I’ll be back this evening to pick it up!’ the customer said before heading off for shopping.

With these kinds of knives, I feel like there’s a very specific angle—the “absolute angle”—that the blade edge needs to match. The absolute angle is the ideal edge angle, and in simple terms, it’s more obtuse. The knife may have been sharp at first, but now the edge is just not there.

To deal with this, you have to find that absolute angle, or you won’t get it sharp again. Most new knives have sharpening marks running straight down to the edge, so I positioned the knife at a right angle to the whetstone and sharpened it with a medium grit stone, like I was sharpening a hand plane.

And guess what? It worked! I was in a good mood, thinking, ‘Yes! Got it!’ But, of course, I got greedy and went for the finishing stone. That’s when things went downhill… the edge stopped cutting! What happened?

Turns out, a thin convex edge had formed, and it was messing everything up. Wiggling the blade back and forth on the stone didn’t help. I was getting stuck in a downward spiral until I decided to check the packaging the knife came in.

Sure enough, there it was: ‘Use a synthetic medium grit stone.’ Following the instructions, I sharpened the knife with the synthetic stone, and while it wasn’t perfect, it did bring the edge back to a decent cutting condition.

It was a bit of an anticlimax, but I guess this is one of those ‘matching the stone to the knife’ situations. I’m still a bit puzzled by the whole thing, but hey, it’s another trick up my sleeve, haha.

By evening, the store’s counter was like the checkout line at a supermarket with housewives waiting to pick up their knives. I’m sure tonight’s dinner was a fun one for everyone！

• 2012-07-20