Basic sharpening question

[ademjashari]

I’m hoping someone in this community of smart and knowledgable metal freaks can explain (as specifically/technically as possible) why when sharpening you only put pressure on the out/push stroke, i.e. when sharpening holding the knife in your right hand with the edge facing you. If the goal is to remove metal, wouldn’t it be more effective to apply pressure in both directions?

I am particularly confused because I was recently instructed by the longtime employee of a very prestigious knife maker in Japan, and he said when he sharpens the left edge, instead of switching the knife to his left hand he turns the knife around so that the edge is facing away, into the stone, and he applies pressure on the push/out stroke. This contradicted what I thought was commonly held sharpening practice.

What happens to the edge when you sharpen this way, i.e. with the edge facing away? And what's the reason to apply pressure in only one direction?

Hope this makes sense and apologies if this has been answered elsewhere. Thank you.

 

[jedy617]

Maybe I've been doing something wrong for all these years but I do light pressure on each push and pull. I know for uraoshi sharpening for single bevels you only put pressure when pulling back I believe, correct me if I'm wrong

 

[Bear]

I always thought it was to prevent gouging softer stones.

 

[HumbleHomeCook]

I don't stress it at all.

 

[JustAnotherJoe]

Scince of Sharp has a great summery

When honing a blade in the edge-leading direction, steel is removed in two ways; abrasion of the bevel surface and the ‘breaking’ or ‘micro-chipping’ away of the apex. This micro-chipping process prevents the formation of a burr, but also limits the level of keenness that is achieved. In the edge-trailing stroke, the occurrence of micro-chipping is reduced to the point where a burr or foil will almost inevitably be formed.

https://scienceofsharp.com/2015/02/09/the-pasted-strop-part-1/
There he has a few SEM images in that article that show it.

 

[ademjashari]

Scince of Sharp has a great summery

https://scienceofsharp.com/2015/02/09/the-pasted-strop-part-1/
There he has a few SEM images in that article that show it.

This is amazing thank you.

 

[Kawa]

When sharpening, same pressure both ways.
Its hard enough to not change angle (on a microscopic level) between push and pull. Let alone if I also have to switch pressure...

When deburring though, only edge leading, so you end with the best way to remove burr, but not the keenest edge. Seems to deliver the sharpest result for me

 

[ian]

You’ll might find that you naturally press a bit more on the push, because of ergonomics. I don’t think it matters much for bevel setting. The science of sharp business above is more relevant to the final strokes: edge leading helps to reduce the burr, edge trailing is good for ultimate keenness.

 

[gentiscid]

Do as you please, shqipe!
As long as you maintain angle consistency!

 

[Matt Jacobs]

get some cheaper knives and try different techniques. I put pressure both ways but I am more focused on pressure on the push (edge trailing) stroke. Ultimately you will find what works for you and must practice.

 

[jacobwilder5]

get some cheaper knives and try different techniques. I put pressure both ways but I am more focused on pressure on the push (edge trailing) stroke. Ultimately you will find what works for you and must practice.

This ^

I'm naturally ambidextrous so I was actually more comfortable in just switching hands with the edge always facing me vs. flipping the knife and keeping it in my right hand. I tend to put more pressure on the edge trailing strokes as it moves away but maintain decent pressure as I pull it back. I'll deburr with edge leading and finish with light edge trailing strokes. This is just what works for me though! You don't have to pick any one method just find what works for you.

 

[JustAnotherJoe]

I'm naturally ambidextrous

Not jealous, not at all... I just, umm, prefer the feng shui of having to face the knife way. Yeah....

 

[Heckel7302]

In sharpening there is only one rule, do what works best for you.

 

[Matt Jacobs]

This ^

I'm naturally ambidextrous so I was actually more comfortable in just switching hands with the edge always facing me vs. flipping the knife and keeping it in my right hand. I tend to put more pressure on the edge trailing strokes as it moves away but maintain decent pressure as I pull it back. I'll deburr with edge leading and finish with light edge trailing strokes. This is just what works for me though! You don't have to pick any one method just find what works for you.

its funny you say this. I started sharpening by switching hands. I went to one hand and got substantially better. When I felt like I couldnt improve I tried switching hands again and now I am doing my best sharpening that way.

 

[Benuser]

Edge trailing — certainly with pressure — is useful to remove a lot of steel, but raises a huge burr. Holding a steady angle when edge trailing is far from simple. The angle tends to get lower when further away from the initial position.

 

[cotedupy]

Holding a steady angle when edge trailing is far from simple. The angle tends to get lower when further away from the initial position.

Do you reckon that particularly matters in the grand scheme of things? If it was getting a touch higher it might an issue, but marginally lower I can’t see a problem, might even be a good thing...(?)

 

[jacobwilder5]

its funny you say this. I started sharpening by switching hands. I went to one hand and got substantially better. When I felt like I couldnt improve I tried switching hands again and now I am doing my best sharpening that way.

Yeah I feel like most people might benefit from working through the initial awkwardness and give this method a real shot. Not sure how you feel about it, but I feel like it's easier for my brain to mirror and be more consistent with angle and pressure on both sides this way.

 

[Rangen]

Yeah I feel like most people might benefit from working through the initial awkwardness and give this method a real shot. Not sure how you feel about it, but I feel like it's easier for my brain to mirror and be more consistent with angle and pressure on both sides this way.

Agree. Also, it turned out that my off hand is better at finding the angle consistently.

 

[mpier]

Over the years I have changed my techniques now I tend to run up the stone at an angle with no need to put extra pressure in any one direction. I have found this takes a lot of overthinking pressure points out of the equation, holds the angle better, allows for smaller burrs and removes burrs easer and more completely. Switching hands is also much easier running up the stones rather than perpendicular. With that said if I want to drop a knife down to a low grit to add bite then I’ll run perpendicular with edge training light strokes so not to raise a burr

 

[Benuser]

Do you reckon that particularly matters in the grand scheme of things? If it was getting a touch higher it might an issue, but marginally lower I can’t see a problem, might even be a good thing...(?)

Not exactly, I'm afraid. In by far the most cases where the end result is disappointing, it's simply because the bevels actually don't meet. An angle was too low, longer sharpening with the coarsest stone would have been needed, in the case of a new or unknown knife a microbevel was being overlooked. There may even be a burr, but closer inspection — with marker and loupe — will learn only one side has been sharpened. All work will have to be redone, starting again with the coarsest stone.

 

[cotedupy]

Not exactly, I'm afraid. In by far the most cases where the end result is disappointing, it's simply because the bevels actually don't meet. An angle was too low, longer sharpening with the coarsest stone would have been needed, in the case of a new or unknown knife a microbevel was being overlooked. There may even be a burr, but closer inspection — with marker and loupe — will learn only one side has been sharpened. All work will have to be redone, starting again with the coarsest stone.

Ah yeah, I was thinking about it more in terms of the final stages of sharpening or deburring. I can certainly see your point in regards to earlier stages.

I personally find it almost impossible not to set an apex*, but I do like very thin knives, and at work I use a spinning wheel for setting the edge, which is a lot faster for that kind of thing.




* Having said that, I did manage to do it yesterday.