Those oval scallops down the side of a santoku have a name, a patent, and a sales pitch. The pitch is that food won't stick to the blade. I've owned a few of these knives over the years and I can tell you the potato doesn't read the pitch. On most knives the dimples do close to nothing. On a couple of specific Japanese knives they genuinely work, and it's worth knowing which.

Where they came from

Not Japan, for a start. A Sheffield firm called Granton Ragg patented the scalloped edge back in 1928, which is why old hands in the trade still say "Granton edge" and why Granton carving knives still have it. The Germans call it kullenschliff. Same thing either way: shallow hollows ground into the face of the blade, staggered left and right, sitting a little way above the edge.

It was made for ham. Long thin carving knife, big wet slab of meat, and the hollows trap a bit of air so the slice drops off instead of wrapping itself round the blade. For that one job, fair enough, it helps.

The santoku version, the one you're picturing, came along much later. Early 2000s or so, when Wüsthof and Henckels and then Shun worked out that American home cooks wanted something that looked Japanese. The santoku shape was new to most of them. The scallops made it look engineered. Together they sold by the pallet, and still do. Walk into any department store and I'd bet the santoku facing the aisle has dimples.

Do they do anything?

A bit, sometimes. On a thick Western blade cutting something wet and starchy, potato, cucumber, you might notice slices dropping off a touch sooner. Onion, no. And nothing you do with the front third of the blade changes, because the scallops run out before the tip.

On a thin Japanese blade I'd say they do nothing, and the reason is dull. Food sticks because a wet slice sits flat against a wet steel face and surface tension holds it there. A scallop can only break that if the slice actually reaches it. Measure a hollow-edge santoku and the lowest dimple starts maybe 5 to 8mm up from the edge. Your potato slice is 2mm thick. It never gets near the dimples. It's stuck to the flat strip of steel underneath them, same as it would be on a knife with none.

What actually stops food clinging to a good Japanese knife is the grind. A convex face, thin right behind the edge and swelling gently toward the spine, gives the slice a curve to peel off from. That's why a properly ground 180 santoku with a plain face sheds potato better than a dimpled one from the department store. Nothing to do with scallops.

The two exceptions

Glestain. This Niigata maker does it differently. The hollows on a Glestain are big, deep, oval, and only on one side, and crucially they run nearly all the way down to the edge. The whole right face (for a right-handed cut) is covered in them. Food pressed against that face does let go, noticeably, and there's a real following for these among Japanese restaurant cooks who slice all day. It works because the hollows are where the food is, not where they look nice in a photo.

Tsuchime. The hammered finish on a lot of Sakai and Echizen blades does roughly the same thing by accident. Hundreds of small uneven dents across the upper blade break up the flat surface. Not as effective as a Glestain. Better than nothing, and on a thin blade the dents often sit close enough to the edge to matter. The finishes page covers tsuchime and nashiji and the rest if you're curious.

The downsides nobody puts on the box

Each scallop is steel that isn't there anymore. On a thin blade that leaves a weak band, and I've personally seen a hollow-edge santoku go in the bin after a drop onto tile cracked it straight through a dimple. Rare. But a plain blade can't fail that way.

The other problem is slow. Sharpen a knife for fifteen or twenty years and the edge creeps upward as steel comes off. Eventually it reaches the scallops and you get a wavy, scalloped edge line, which is every bit as annoying as it sounds. If the knife's a five-year purchase, who cares. If it's one you mean to hand down, it matters.

What I'd actually do

Ignore the dimples. Buy on the grind, the steel, and the handle, and if the knife you end up liking happens to have scallops, fine, they're mostly harmless. If what you really want is a knife food doesn't stick to, buy a Glestain or a hammered blade. Not a scalloped one.

And if you've already got a dimpled santoku and potato still sticks to it, you're not doing anything wrong. The dimples were never going to fix that. A thinner edge, a wet blade, and a quicker stroke will do more than any scallop ever did.

Andrew Kuzmin · Editor-in-Chief, Okami Blades