The Burr

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Paul57

Joined
Apr 23, 2023
Messages
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When sharpening a knife do you need to create a burr with each progression of stones? Seems to me that could take quite a bit of time especially in the higher grits.
 
Put simply, you really only need a burr for your initial grit. The most important part of sharpening is making sure that the burr goes across the entire length of the edge. This means you have successfully apexed the entire edge. If you do this part properly with your lowest grit, the following grits are used to remove the burr and refine the edge. You shouldn’t feel a burr at all with a properly finished edge.
 
Sharpoholic said:
Put simply, you really only need a burr for your initial grit. The most important part of sharpening is making sure that the burr goes across the entire length of the edge. This means you have successfully apexed the entire edge. If you do this part properly with your lowest grit, the following grits are used to remove the burr and refine the edge. You shouldn’t feel a burr at all with a properly finished edge.
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Thank you for your quick response, I wasn't totally sure about the remaining grits as for as a burr.
 
I see it a little differently.

Once the apex is reached, the burr will form almost instantly -- if you hold the right angle.

The size of the burr is dependent on how much metal you move/remove. A 100-grit stone passing over perfect apex will move/remove a lot more metal than an 800-grit stone, so the burr will be bigger.

Likewise, heavier, longer strokes will move/remove more metal.

I look for the burr at ever change of grits. With the finer grits, the burr is much smaller and more difficult to feel. It doesn't take any time to create a burr after the original burr is started. You may not be noticing it, because it becomes so fine.

You might also be changing the angle of your stone to a slightly more acute angle, meaning the stone is hitting the shoulder, not the apex, so you don't create a burr at all.
 
Sharpoholic said:
You shouldn’t feel a burr at all with a properly finished edge.
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You won't feel it with your fingers or see it with 60x loupe but small burr could stil be there. This burr will cut paper towel but as soon as you cut something harder it will fold and there it goes the sharpness.
How can you be sure you removed all the burr?
 
Burr at every step. Otherwise, you have no idea if your grit has crossed over at the apex and removed previous scratches.
 
DeadboxHero said:
Burr at every step. Otherwise, you have no idea if your grit has crossed over at the apex and removed previous scratches.
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I use a change in the angle of strokes to "cross out" the previous grit, as even fine scratches from other angle become visible through the reflection of light. Do you believe this is insufficient? Why if so?
 
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Back in March 2023 I ran a in person freehand sharpening competition.

What was noticed was when people went to the 3k polishing stone from the 800grit and they still had 800 grit scratches at the very tip of the apex because they were just going off of the look of the bevel and not a burr. Removing all of the 800 quit scratches without over convexing the edge could have improved their sharpness score. We were able to double check this by looking under the microscope.

However, in their defense there was a lot of pressure in the heat of competition and they were also under a tight time limit.
 
DeadboxHero said:
What was noticed was when people went to the 3k polishing stone from the 800grit and they still had 800 grit scratches at the very tip of the apex because they were just going off of the look of the bevel and not a burr. Removing all of the 800 quit scratches without over convexing the edge could have improved their sharpness score. We were able to double check this by looking under the microscope.
Click to expand...
What kind of steel?
 
DeadboxHero said:
What was noticed was when people went to the 3k polishing stone from the 800grit and they still had 800 grit scratches at the very tip of the apex because they were just going off of the look of the bevel and not a burr. Removing all of the 800 quit scratches without over convexing the edge could have improved their sharpness score. We were able to double check this by looking under the microscope.
Click to expand...

Which stones were these?
 
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