Very simply put, the data presented above indicates that when stressed under only 150gf, with a starting sharpness of 150-170, a RHC 60-61 blade is no more resistant to rolling, (dulling), than a RHC 55-57 blade until the edge has rolled to a sharpness reading of 500+. I think we would all agree that 500+ sharpness is a dull blade in need of maintenance.
To put it another way, as far as resistance to initial dulling goes, a $45.00 Henckel performs as well as a $150.00 Shun until the blades have dulled to 500+ sharpness.
To put that in perspective, 150g is not much force. I placed a small potato (maybe 2” diameter) on a scale and cut it with a ~200 sharpness blade. The pressure needed to cut the potato was ~4.5lb (2,041g) or ~93% more pressure than the SET (Structural Edge Test) applies to the edge.
But wait! There’s more! A harder steel blade may actually be a disadvantage, not only because it’s more difficult to sharpen, but also more prone to chipping. From the Shun website FAQ: https://shun.kaiusaltd.com/faq
“WHY DID MY KNIFE CHIP WHEN I WAS JUST CHOPPING VEGETABLES?
Chips can happen due to improper cutting technique. Shun Cutlery is designed to be used in a smooth, slicing motion—and never in a forceful, up-and-down “chopping” manner.”
Um, hmm… Jump to 2:45 into this video and watch:
https://www.youtube.com/watch?v=nffGuGwCE3E
I realize this data runs contrary to established wisdom and even common sense. After all, it only makes perfect sense that a harder blade would be more resistant to dulling, right? Right! Absolutely right. But, one of the reasons why it is not relevant to knife edges is because our blade edges are so thin and the amount of force applied to edges during normal use far exceeds the differential hardness advantage between RHC 57 and RHC 61 steel.
In other words, one brand of wet toilet paper may support the weight of 1 quarter dollar coin, while another will support 5 quarters before the dreaded tear through occurs. 5X as much weight! But neither can a support a 5lb bag of sugar. If the goal is to support a 5lb bag of sugar, the difference in strength in this case is irrelevant.
There very well may be an advantage to a harder steel edge sharpened to a toothy 300+ sharpness with a thick 20° bevel angle compared to a similar edge of softer steel. But, the presented data clearly shows no advantage with a harder steel blade at 150 sharpness and an acute bevel angle compared to a similar blade of softer steel.
Our esteemed Exchange member Thomas (Edgepal) has often stated something to the effect that no edge should be sharper than is needed for a particular task, and that the task at hand determines the blade used. Great wisdom there methinks.
For me, this is causing reconsideration of the 150 edge that I have always held so dear. I’m starting to think that for a general purpose blade, a 300 toothy edge will be far more useable, durable and require less maintenance. After all, what is the point of sharpening to 150 if after cutting a bag of carrots the blade dulls to 300?
I think this offers a huge opportunity for both knife makers and sharpeners. The key will be in understanding what steel, bevel angel and edge finish produces edges that perform the best for the task the blade will be put to.
To put it another way, as far as resistance to initial dulling goes, a $45.00 Henckel performs as well as a $150.00 Shun until the blades have dulled to 500+ sharpness.
To put that in perspective, 150g is not much force. I placed a small potato (maybe 2” diameter) on a scale and cut it with a ~200 sharpness blade. The pressure needed to cut the potato was ~4.5lb (2,041g) or ~93% more pressure than the SET (Structural Edge Test) applies to the edge.
But wait! There’s more! A harder steel blade may actually be a disadvantage, not only because it’s more difficult to sharpen, but also more prone to chipping. From the Shun website FAQ: https://shun.kaiusaltd.com/faq
“WHY DID MY KNIFE CHIP WHEN I WAS JUST CHOPPING VEGETABLES?
Chips can happen due to improper cutting technique. Shun Cutlery is designed to be used in a smooth, slicing motion—and never in a forceful, up-and-down “chopping” manner.”
Um, hmm… Jump to 2:45 into this video and watch:
https://www.youtube.com/watch?v=nffGuGwCE3E
I realize this data runs contrary to established wisdom and even common sense. After all, it only makes perfect sense that a harder blade would be more resistant to dulling, right? Right! Absolutely right. But, one of the reasons why it is not relevant to knife edges is because our blade edges are so thin and the amount of force applied to edges during normal use far exceeds the differential hardness advantage between RHC 57 and RHC 61 steel.
In other words, one brand of wet toilet paper may support the weight of 1 quarter dollar coin, while another will support 5 quarters before the dreaded tear through occurs. 5X as much weight! But neither can a support a 5lb bag of sugar. If the goal is to support a 5lb bag of sugar, the difference in strength in this case is irrelevant.
There very well may be an advantage to a harder steel edge sharpened to a toothy 300+ sharpness with a thick 20° bevel angle compared to a similar edge of softer steel. But, the presented data clearly shows no advantage with a harder steel blade at 150 sharpness and an acute bevel angle compared to a similar blade of softer steel.
Our esteemed Exchange member Thomas (Edgepal) has often stated something to the effect that no edge should be sharper than is needed for a particular task, and that the task at hand determines the blade used. Great wisdom there methinks.
For me, this is causing reconsideration of the 150 edge that I have always held so dear. I’m starting to think that for a general purpose blade, a 300 toothy edge will be far more useable, durable and require less maintenance. After all, what is the point of sharpening to 150 if after cutting a bag of carrots the blade dulls to 300?
I think this offers a huge opportunity for both knife makers and sharpeners. The key will be in understanding what steel, bevel angel and edge finish produces edges that perform the best for the task the blade will be put to.