Thread: Knife sharpening for different tasks

Yeah like that, if it pops hairs it’s good to go. I have one of those small Falkniven diamond stones in my hunting kit but I don’t think I’ve ever had to use it on my own knives in the field, just mates ones. A quick strop and it will usually still shave hairs.
I had watched a few butchery vids to learn a bit more and noticed how often they will run their knife along a steel. Most of their knives seem to be a general meat works knife and wondering if any butchers are starting to use better steel for their knives as some of the new stuff has far better edge retention. If you take it to its conclusion it seems to make sense to sharpen less often. I have a couple of very good steel blades and heaps of cheaper ones and the edge retention is night and day.

If your eyesight is good enough, and the sunlight is on par and playing nicely - once you have the knack you can hold the knife in the sun and get a very good idea if it's sharp or not just by the way the light plays the edge as you hold the knife.

The paper test is also a good one, although a paper towel is a bit better I think than something fine-grained like printer A4 which tends to cut really cleanly. Paper towels are much more fibrous and coarse-grained, as well as more loosely bound so they will rip and tear easier than cutting cleanly. Knife is sharp if it cuts a paper towel without catching!

Mjc/Mark your level of sharpness, I think, is good for processing game. For those wondering, Mark uses good steels (incl magnacut) and will slice a hair length ways by only holding one end. It's impressive. Keep knives sharp and just strop them to keep them that way, then jump onto a stone when you need to.

Re the toothy edge theory, I've also heard this from people who know their knives and do it professionally, but I don't really get on board with it. Due to preferring to do lots of different tasks with a knife, I think the hair-popping sharpness is best.

Originally Posted by Mjcbows

Yeah like that, if it pops hairs it’s good to go. I have one of those small Falkniven diamond stones in my hunting kit but I don’t think I’ve ever had to use it on my own knives in the field, just mates ones. A quick strop and it will usually still shave hairs.
I had watched a few butchery vids to learn a bit more and noticed how often they will run their knife along a steel. Most of their knives seem to be a general meat works knife and wondering if any butchers are starting to use better steel for their knives as some of the new stuff has far better edge retention. If you take it to its conclusion it seems to make sense to sharpen less often. I have a couple of very good steel blades and heaps of cheaper ones and the edge retention is night and day.

Most ive worked with just still use the old known soft stuff. Ive done a few boning knives for commercial use but all for chefs rather than butchers.

In reality boning/butchery work isnt very hard on an edge in the hands of an experienced butcher as meat doesnt dull an edge and they are good at not smashing bones.

Originally Posted by Pistol

Re the toothy edge theory, I've also heard this from people who know their knives and do it professionally, but I don't really get on board with it. Due to preferring to do lots of different tasks with a knife, I think the hair-popping sharpness is best.

Look up the Victorinox Paring Knife, they do a wavy edge version for that reason. Very popular with commecial fishermen.

Yeah like that, if it pops hairs it’s good to go. I have one of those small Falkniven diamond stones in my hunting kit but I don’t think I’ve ever had to use it on my own knives in the field, just mates ones. A quick strop and it will usually still shave hairs.
I had watched a few butchery vids to learn a bit more and noticed how often they will run their knife along a steel. Most of their knives seem to be a general meat works knife and wondering if any butchers are starting to use better steel for their knives as some of the new stuff has far better edge retention. If you take it to its conclusion it seems to make sense to sharpen less often. I have a couple of very good steel blades and heaps of cheaper ones and the edge retention is night and day.

I find that if I polish my edge too far it doesnt slice as well as if I leave it a bit rougher. I prefer my kitchen knives off a 1000grit stone rather than taking them up to 8000grit.

Below is a video of a guy who agrees with me For a slicing knife he only goes to 600grit and then lightly strops it, with the goal of being a 'polished but toothy' edge that has some 'stick' when dragged along the back of his fingernail. For a chopping knife like a cleaver or machete he will use a buff and polishing compound to get up to a mirror finish.

https://www.youtube.com/shorts/MDsBWkRWHmg

Originally Posted by MichaelB

I find that if I polish my edge too far it doesnt slice as well as if I leave it a bit rougher. I prefer my kitchen knives off a 1000grit stone rather than taking them up to 8000grit.

Below is a video of a guy who agrees with me For a slicing knife he only goes to 600grit and then lightly strops it, with the goal of being a 'polished but toothy' edge that has some 'stick' when dragged along the back of his fingernail. For a chopping knife like a cleaver or machete he will use a buff and polishing compound to get up to a mirror finish.

https://www.youtube.com/shorts/MDsBWkRWHmg

Polishing is an art form - it's really not easy to keep the edge 'alive' and get it nice and shiny. Thats why the japanese knives are so incredibly sharp - they have mastered the art of polishing without rolling the point of the edge over to one side.

With a polished edge, you know it's good when you can't removed wood off a block on either side of the knife when scraping it backwards over the wood, laying almost flat and the opposite to trying to cut. If there is any sort of roll on one side of the edge it will remove the faintest hint of timber - and it won't cut. Leaving the edge a bit rougher or unpolished is (for those of us that are normal mortals and not at the japanese level of mastery) a far easier way to an acceptably sharp edge.

Originally Posted by No.3

Polishing is an art form - it's really not easy to keep the edge 'alive' and get it nice and shiny. Thats why the japanese knives are so incredibly sharp - they have mastered the art of polishing without rolling the point of the edge over to one side.

With a polished edge, you know it's good when you can't removed wood off a block on either side of the knife when scraping it backwards over the wood, laying almost flat and the opposite to trying to cut. If there is any sort of roll on one side of the edge it will remove the faintest hint of timber - and it won't cut. Leaving the edge a bit rougher or unpolished is (for those of us that are normal mortals and not at the japanese level of mastery) a far easier way to an acceptably sharp edge.

That's just a burr not really a rolled edge. Finish with some alternating edge leading deburring strokes at the end of your course grit stone then problem solved. Can polish as high as you like and won't have any issue with the burr. Raising a burr is the best way to ensure you have full apexed the edge.

The main reason japanese knives are so apparently sharp is the geometry. They are way thinner with lower edge angles, all leads to better cutting performance.

I was given this by an American hunter.
The first job I did with it was head skin a Sika.
Sika have quite tough skin up the back of the neck, and this thing went through it better than anything I've used before. And I have skinned quite a few.
It's a slow process sharpening it with a round stone though.
As a general purpose skinning and meat cutting knife I have a hard time getting my head around the serrated cut feel.
A bit like when I drop a knife and ding the edge. Every stroke sends a bad thought through my head.

Originally Posted by No.3

Polishing is an art form - it's really not easy to keep the edge 'alive' and get it nice and shiny. Thats why the japanese knives are so incredibly sharp - they have mastered the art of polishing without rolling the point of the edge over to one side.

With a polished edge, you know it's good when you can't removed wood off a block on either side of the knife when scraping it backwards over the wood, laying almost flat and the opposite to trying to cut. If there is any sort of roll on one side of the edge it will remove the faintest hint of timber - and it won't cut. Leaving the edge a bit rougher or unpolished is (for those of us that are normal mortals and not at the japanese level of mastery) a far easier way to an acceptably sharp edge.

Freehand sharpening with a stone can be an art form, sure. But there are plenty of guided systems these days that take the angle error out of the equation so that a rolled edge is pretty hard to come by. I find a 1000 grit edge will cut a chicken breast better than a 8000 grit edge, but the 8000grit will last longer

Originally Posted by Nick-D

That's just a burr not really a rolled edge. Finish with some alternating edge leading deburring strokes at the end of your course grit stone then problem solved. Can polish as high as you like and won't have any issue with the burr. Raising a burr is the best way to ensure you have full apexed the edge.

The main reason japanese knives are so apparently sharp is the geometry. They are way thinner with lower edge angles, all leads to better cutting performance.

Up to a point - not just geometry its the steel and heat treatment as well. The thinner edge is more prone to rolling and burring on most production 'western' blades - so they go for a coarser angle to give the edge more strength.

The burr is the result of dragging the edge over the sharpening surface - not really what I'm meaning with the polished edge and the roll to one side that is way more regular than a burred edge. Kinda needs the microscope treatment to see what's going on - the burred edge is almost like mini serrations where a properly polished and straight edge is damn dangerous it's that sharp. Very hard to get a mirror polished edge right without good kit. The confusion there I think might be with the folded edge from use which gets called the 'rolled' edge as well - or I guess a 'rolled over' edge. It's a bloody art form all right, the old polished edge job!

Angle is critical. At the local freezing works they have a knife sharpening robot that is set at 18 1/2 degrees I think. Laser checks/scans the knife, through two sets of belts then a buff wheel. About 30 seconds I think. Unless it needs a another go. Then boners look like serial killers when they are steeling it. Avid concentration, maybe 2 slow deliberate strokes with the diamond steel and good to go lol. Although they do have a hand held unit for knifes that the robot can't do, or maybe just don't want to use the bot.
That angle seems to be a great compromise for most things at the works.
And also handy as if my knives are a bit naff I go and see the knife sharpener and he sharpens them for me haha.

Originally Posted by No.3

Up to a point - not just geometry its the steel and heat treatment as well. The thinner edge is more prone to rolling and burring on most production 'western' blades - so they go for a coarser angle to give the edge more strength.

The burr is the result of dragging the edge over the sharpening surface - not really what I'm meaning with the polished edge and the roll to one side that is way more regular than a burred edge. Kinda needs the microscope treatment to see what's going on - the burred edge is almost like mini serrations where a properly polished and straight edge is damn dangerous it's that sharp. Very hard to get a mirror polished edge right without good kit. The confusion there I think might be with the folded edge from use which gets called the 'rolled' edge as well - or I guess a 'rolled over' edge. It's a bloody art form all right, the old polished edge job!

A burr formed on a fine grit can be very even. Corners stone create a large more ragged burr.

Japanese sharpening absolutely is an art form, but its actully more focused on the polish and finish, rather than about absolute edge sharpness. Traditionally its not uncommon for the knife to be delivered unsharpened or only with a very basic edge bevel allowing for the owner to set there preferred edge angle and stone finish.

The sharpener is also generally the person who sets the knife geometry and does the bevel grinding etc. There are makers that do both, but its very common to have a pair of blacksmith and sharpener. Its a pretty cool rabbit hole as there are even mystery sharpeners sharpening under pseudonyms to be able to do a different grind or style than the one they are known for.