Poor Edge Retention

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MatthewSB

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Feb 1, 2013
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I've been using my S35VN Sebenza 21 for months now, touching the edge up using a strop loaded with black and green Bark River compound. I start with the black, then finish with the green. My edges are hair popping sharp at first, but seem to dull quickly. I'm pretty sure that I don't have a wire edge, I check both sides with my thumbnail.

I've read that stropping can lead to poor edge retention, can anyone explain why?

Before someone says "use a Sharpmaker, like CRK says to" my knife was ground too obtuse at the factory and the Sharpmaker doesn't even contact the edge. I have a Wicked Edge sharpener, but I'm trying to avoid undoing the factory convex edge for a regular V edge.

I'm getting closer and closer to trying a 40 degree V edge, what do you think?
 
When you say dull do you mean not cutting at all or just going to a "working edge"? Depending on how much you polish an edge it can lose that really high level of sharpness pretty quickly. In my experience with s30 and s35 it will lose its super hair splitting edge fairly fast but keep a decent edge for a very long time.
On a side note- If you have a wicked edge and you are planning on keeping and using the knife I say put your own edge on your knife:thumbup:
 
Ernie1980 said:
When you say dull do you mean not cutting at all or just going to a "working edge"? Depending on how much you polish an edge it can lose that really high level of sharpness pretty quickly. In my experience with s30 and s35 it will lose its super hair splitting edge fairly fast but keep a decent edge for a very long time.
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I have to agree with this. All three of my CRK's get extremely sharp easily but don't stay that way. They stay very very sharp for awhile but that light saber edge doesn't stay long.
 
Resharpen the knife to 20 degrees per side. You may be over stropping the edge, making it too thin which will cause it to dull quicker.
 
If you have a Wicked Edge and know how to use it properly, I think you'll enjoy your knife more with a good V edge. I know I do.
 
I just use ordinary DMT bench hones to sharpen my Sebbie's S35Vn (well, practically all of my blades, too). It takes a fantastic edge and holds it substantially longer than most other steels, in my experience, though not forever, of course. Depends what you're cutting.
 
Alberta Ed said:
I just use ordinary DMT bench hones to sharpen my Sebbie's S35Vn (well, practically all of my blades, too). It takes a fantastic edge and holds it substantially longer than most other steels, in my experience, though not forever, of course. Depends what you're cutting.
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^^This!!
 
Stropping can cause a small burr to form that will shave but once you use the knife will result in the burr folding over.
 
You answered your own question. Too obtuse, put it on your wicked edge. I prefer 25deg each side on all my knives with a blade thickness similar to a sebenza. Once you reprofile youll be able to maintain that edge longer by stropping.
 
Ernie1980 said:
When you say dull do you mean not cutting at all or just going to a "working edge"?
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I mean dull :o

kwackster said:
What is the birth date of your S35VN Sebenza 21 ?
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Early 2015

marthinus said:
Stropping can cause a small burr to form that will shave but once you use the knife will result in the burr folding over.
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I check for a wire edge every time I sharpen.

daisy cutter said:
You answered your own question. Too obtuse, put it on your wicked edge.
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Indeed. Thanks for the thoughts everyone :D
 
Just so I understand correctly...

You strop the blade with compond, it gets very sharp, then the edge quickly dulls to "I mean dull", then you are able to bring it back to "hair popping" with just a "touchup" on a loaded strop?

If I am understanding properly, then you are experiencing something I have never experienced with any knife, and I can only suggest you send it to CRK for assessment. Seriously, there must be something horribly wrong if you are able to sharpen to hair popping sharp from dull with only a touchup on a manual strop.
 
Constant Gardener said:
Resharpen the knife to 20 degrees per side. You may be over stropping the edge, making it too thin which will cause it to dull quicker.
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I agree, except I do 15 degrees with a 20 degree microbevel.

I don't believe CRK puts a true convex edge on their blades, that's why they recommend the Sharpmaker. A true convex knife has to be sharpened with a slack belt, or with sandpaper on a slightly soft surface (e.g. cardboard). I have one knife like that, done by a Mastersmith, and it certainly is not the same edge as on a Sebenza. IIRC, the sebenza edge has a little convex character due to the use of a belt for final sharpening, but you've put your own edge on it by now.
 
You asked why stropping reduces edge retention and I have yet to see an answer to that here, so let me try to explain. When you are stropping the edge, you're bending the steel back and forth to reshape it at a micro level. This puts stress on the steel at the edge. While you're able to knock the edge straight with some stropping, making it sharper and able to cut better temporarily, you are weakening the the edge at it's apex the more you strop it. After a few stropping sessions, its too weak at the edge to retain its sharpness. At this point, since you've stropped it a lot, I'd agree with the others and put it on either the WE or SM. WE will change the profile to a V but it's way easier than trying to spend centuries knocking the shoulders off a very wide edge on the SM.

Hope this helps.

Regards,
 
Thanks for the responses everyone, and sorry for the late reply. I wanted to give enough time to provide an accurate update.

I put a crisp 40 degree edge on my Sebenza using my Wicked Edge. It cuts way better now, at least for my EDC tasks, and I haven't had any edge damage whatsoever. Did I mention how well it cuts now? It's been 2 weeks and it still shaves (barely ;) ) after slicing up a lot of cardboard, a few zipties, and a bit of carpet. I couldn't be happier :D

I know that my knife had a very obtuse edge from the factory because a sharpmaker would only touch the shoulders and wasn't near the edge. I'm guessing that months of weekly stropping further increased the edge angles. Regardless, the knife cuts great now, hasn't needed a sharpening in a couple of weeks. When the time does come to touch up the edge, I'll be using flat stones from now on.

Thanks again, everyone!
 
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