First post and a sharpening question

[CowryX]

Greetings,

What an awesome forum! I have been reading and learning from so many people around these parts.


I was lucky enough to buy a bunch of whetstones from a person who abandoned honing straight razors. I have been learning to sharpen knives for about 6 months. I have been enjoying the learning and experience, thoroughly!

I have Chosera 400, 1k, 3k, 5k, and Shapton 8k. I don’t use a strop. I strop on each stone before moving on to the next. The edges on my knives are super sharp. I love them. But I noticed that a tiny bulge (convexing) happens close to the cutting edge. I searched on the forum and saw a comment about micconvexing and Chosera stones. Is this something I’m doing or is it the nature of these stones?

 

[daveb]

Welcome

 

[stringer]

Greetings,

What an awesome forum! I have been reading and learning from so many people around these parts.


I was lucky enough to buy a bunch of whetstones from a person who abandoned honing straight razors. I have been learning to sharpen knives for about 6 months. I have been enjoying the learning and experience, thoroughly!

I have Chosera 400, 1k, 3k, 5k, and Shapton 8k. I don’t use a strop. I strop on each stone before moving on to the next. The edges on my knives are super sharp. I love them. But I noticed that a tiny bulge (convexing) happens close to the cutting edge. I searched on the forum and saw a comment about micconvexing and Chosera stones. Is this something I’m doing or is it the nature of these stones?

Welcome to the forum. Hand sharpening without a jig will naturally convex the edge bevel a little. Just because you aren't a machine so you don't exactly hit the apex every time. And if you use Japanese style scrubbing motions there will be some wobble when you change directions. Softer stones and/or dished stones can amplify this affect. I don't believe that the Choseras are considered to be soft although I don't own any. I have the SG 8k and it's definitely not soft. The stones wouldn't have much to do with it. Just the nature of doing stuff by hand.

However, it's not always a bad thing. The best kitchen knife grinds in my opinion are thin behind the edge with convexity on the side that faces the food that's being cut off. This aids food release. At or near the apex, some microconvexity will further aide food release, even in very thin laser knives. But it will also add strength. So thin behind the edge with a more conservative and slightly convex final cutting bevel is a nice balance between thicker grinds that wedge in hard produce and thin grinds that sustain damage easily. You sacrifice a tiny bit of ultimate sharpness

That's just my general strategy. There are other ways. But mostly if you're hand sharpening a little convexity is unavoidable and not necessarily a negative thing. I used to like to sharpen on a wobbly table at work because I thought it improved my edge stability. Don't really know if it did. But the table was usually free.

If you do searches for microconvexity asymmetry grind, etc on the search bar or adding the term site:kitchenknifeforums.com to a Google search you will find lots of old threads.

 

[CowryX]

@stringer Thank you so much for the detailed explanation. I now need to find a wobbly table

 

[Benuser]

Welcome, aboard!
As a Chosera user, I can't say I'm that surprised — but still aren't sure it has to do with the stones or your technique, and if it isn't desirable. I'm always looking for a convexed bevel, at least for the dominant side. I know from the Naniwa Pro 3k compared to the Shapton Glass 4k it has a much wider range of abrasives: when I first used the SG on a well-maintained edge I noticed it took a lot of time and took away the convexity at the very edge, what a user here could explain as I did. This doesn't mean it is true for all Choseras or Shaptons, Pro or Glass. At this level all stones within the same series have a very own character and different properties.
You may considering choosing for edge leading instead of stropping at the end of the sharpening. I can't believe it will make such a huge difference where the convexity is concerned: it anyway improve your edge and add stability. It helped me a lot and even if it wasn't that simple to change habits after tens of years, it was well worth it. It skips the formation of a new burr wile abrading the old one. The edge leading motion is exactly the opposite one of the traditional stropping one that starts with the tip at your closest left stone edge, ending at the heel on your right, provided your a right-hander.
If you want to see whether you really touch exactly the very edge, use a sharpie and a 10x loupe. You will be surprised how much difference a loupe makes.

 

[Se1ryu]

Welcome to the forum @CowryX
You have a lot of good whetstone there.

 

[CowryX]

@Benuser Thank you for the advice. I'll try the edge leading process instead of stropping.

 

[CowryX]

Welcome to the forum @CowryX
You have a lot of good whetstone there.

Now I want t buy other stones! I'm not sure why. These stones I have are superb.

 

[Se1ryu]

Now I want t buy other stones! I'm not sure why. These stones I have are superb.

Yup, we always wanna buy new stuff. Buying more stones and knives
NP with that and it's a great because we can try other stones and knives that will fit our needs.

 

[ian]

What @stringer said. Also, are you stropping at a higher angle than you’re sharpening?

 

[CowryX]

What @stringer said. Also, are you stropping at a higher angle than you’re sharpening?

Yes! I did a few tests with lowered stropping, it helped in reducing the convexity. Thank you.

But the best tip is from @Benuser. It is brilliant! Edge leading stropping seems to remove burr much quicker than more traditional stropping motions. I now have almost no convexity on the knives.

I do like the micronvex effect, though, not on all my knives.

 

[Benuser]

Yes! I did a few tests with lowered stropping, it helped in reducing the convexity. Thank you.

But the best tip is from @Benuser. It is brilliant! Edge leading stropping seems to remove burr much quicker than more traditional stropping motions. I now have almost no convexity on the knives.

I do like the micronvex effect, though, not on all my knives.

Great! You may now check with your nail whether both bevels are equally smooth. A little warning here: not only for cutting, but it does have social consequences: if you're a construction worker nobody will care, but as a dentist...
If needed a few very light longitudinal strokes at a slightly highly angle, flying over the edge, may grasp the last burr remnants. Not edge leading, or trailing, but along the edge.

 

[WilliamDallas]

Welcome to the forum. Hand sharpening without a jig will naturally convex the edge bevel a little. Just because you aren't a machine so you don't exactly hit the apex every time. And if you use Japanese style scrubbing motions there will be some wobble when you change directions. Softer stones and/or dished stones can amplify this affect. I don't believe that the Choseras are considered to be soft although I don't own any. I have the SG 8k and it's definitely not soft. The stones wouldn't have much to do with it. Just the nature of doing stuff by hand.

However, it's not always a bad thing. The best kitchen knife grinds in my opinion are thin behind the edge with convexity on the side that faces the food that's being cut off. This aids food release. At or near the apex, some microconvexity will further aide food release, even in very thin laser knives. But it will also add strength. So thin behind the edge with a more conservative and slightly convex final cutting bevel is a nice balance between thicker grinds that wedge in hard produce and thin grinds that sustain damage easily. You sacrifice a tiny bit of ultimate sharpness

That's just my general strategy. There are other ways. But mostly if you're hand sharpening a little convexity is unavoidable and not necessarily a negative thing. I used to like to sharpen on a wobbly table at work because I thought it improved my edge stability. Don't really know if it did. But the table was usually free.

If you do searches for microconvexity asymmetry grind, etc on the search bar or adding the term site:kitchenknifeforums.com to a Google search you will find lots of old threads.

Thanks for that! Learned a lot from that post