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The S-grind is a modern application of the age-old technique of fullering, as applied specifically to kitchen cutlery, in order to improve food release (anti-stick) or put another way, reduce food “striction” (food items sticking to the blade) and reduce cutting resistance (anti-wedge).
Food striction is most notable when cutting vegetables like potatoes, onions, courgettes, carrots and the like. The slices tend to stick to and stack up on the side of the blade, which knife users find annoying, takes time to clear, and reduces the precision of cuts.
Most production knives are fully flat ground, which food just loves to stick to. To solve this the production knife industry (Wusthof, Shun, etc) has been marketing “Graton” or scalloped bevels. These are the scalloped dimples you would have seen on the side of the blade, which aims to create an air pocket between the food item and the blade, thus breaking the surface tension and allowing the newly cut food item to fall away. While functional it does reduce the life span of the knife because as you sharpen the knife, you’ll eventually raise the edge up into the scalloped area of the blade.
Traditional Japanese bladesmiths use hammered, kurouchi or Nashiji textures on their bevels to add artistic beauty and the dimpled texture aids somewhat in alleviating the sticky problem above. Read my post on Advanced Chef Knife Grinds.
Wedging is most notable in tall and hard ingredients like butternut, pumpkin etc where the friction on the knife blade increases as more of the blade’s surface comes into contact with the foodstuff. Wedging can also be audible, which is common if you hear the food “crack” apart as the thickness of the blade’s shoulders (shinogi) forces the food apart faster than the edge can cut down.
Enter the S-Grind:
The Japanese makers Takeda, Shigefusa and Kohetsu are well known for hand forging in wide hollows/”s-grinds” into their bevels for presumably a good long while. The s-grind as we know it today was arguably popularised by Robin Dalman of Stockholm, Sweden in or around 2015 (as far as my internet searches have been able to ascertain) and has since taken over the world of high-end custom chef knives, especially knives by western makers.
Many makers well know western makers like Mareko Maumasi, Salem Straub (to name but a few) have also used their own interpretation or variation of the s-grind to good effect in their knives.
Essentially the s-grid facilitates a blade that is both lightweight and strong (usually as thicker stock is needed), as well as producing great food release.
The blade has a convex ground primary bevel and then has two hollow grinds running the length of the bevel (one on each side) to reduce the surface area above the blade road so there is less blade for the food to stick to. This results in a concave/convex cross-section (pictured right).
There are subtle variations to this though. Robin Dalman (pictured above) uses a double concave on the primary bevel, and then again in the blade bevel (concave/concave).
The hollows are typically inlaid with a 72″/2m, 48″/1.2m, 36″/1m or similar radiused platen that simulates a large circumference wheel. Some makers will use a large wheel if their grinder can accommodate one. Japanese makers will still either hammer the hollow in during forging or grind the subtle concavity in with large water grinding wheels.
As with many things in life, the following saying remains true, “There are many ways to skin a cat“.
The s-grind promises excellent food release, low striction when cutting food items. This does need to be fined tuned to perform at its best, as the hollow doesn’t guarantee all food will magically fall to the board. The user’s cutting technique also plays a key role in popping the food off the blade as well.
Another benefit that is also found in convex grinds is the ease of cutting or in other words, minimalising wedging in harder food items like carrots, or butternut. Full flat grinds tend to wedge and then crack the food apart and you can definitely hear, feel and see this in action. By purposefully providing relief to the initial cutting edge, convex and s-grinds allow the blade to keep cutting all the way through the food. It almost drops or accelerates through without any effort.
A good chef knife will be tapered both from the handle to the tip (distal taper) and from the spine to the edge. Knives that are considered “laser” class are gound incredibly thin for increased cutting performance. This can introduce a bit more flex than you may like. By having the hollow in the blade, the resultant peak creates a stiffening ridge that allows the thin blades to be both light and stiff.
The first s-grind I attempted was in 2019 for a custom-ordered santoku chef knife. A little bit of testing in the kitchen confirmed most of what I read and heard from other makers. My knives usually surprise people who pick them up at a knife show for how light they are and that’s just because of how thin I can grind them, along with the distal tapers. In combination with the s-grind, I can use thicker stock (4mm) and still achieve excellent cutting performance and balance.
I have a custom-made 2-meter equivalent radiused platen that produces very subtle hollows. It allows me not to grind through the middle of the blade and to “blend” the hollow during the final hand sanding phase. In the right light, you can see it, but I like the fact it’s not obvious.
I’ve done some rudimentary testing in my own kitchen on some test knives (aka knives that didn’t make the grade), so for the most part, yes, the s-grind is worth using. It certainly takes more effort and time to make, but the results, when done well are worth it. You’ll notice a big difference not with just food release, but with reduced wedging, especially if all your current knives are full flat grinds.
That said, just because a knife has an s-grind, doesn’t mean it’s going to be a great performer in the kitchen…
The main thing to look for in a high-end kitchen knife that has an s-grind is the thinness behind the edge. That thinness combined with the s-grind will translate into a fabulous cutting tool that you simply can’t buy outside of the custom knife world.