Polished edge vs mirror polished edge?

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monk3yfist

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Mar 24, 2009
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I see a lot of posts about how a mirror polish improves cutting performance. I take my edges through the grits and end with a leather strop with compound then plain leather. The edge is polished but not exactly a mirror. How much more would I get out of a mirror edge? Thanks.
 
uhhhhh elaborate a bit more please? I got a mirror polish on all of my knives they cut waaaaay better than any other edge i had i feel like a regular edge "saws" more than cuts through
 
A "polished edge" does not have the same meaning to everyone. To me its when the wavelength of light is larger than the scratch therefore you are unable to see any scratches. If you sharpen to 1k then polish with 50k strop compound then you have a 1k edge that's been stropped with 50k compound and not a 50k edge. It's "polished" but far from mirror polished.

The review by Steven was not bad but I'm a bit confused considering his original feedback was much different. Maybe he would like to comment?
 
RokBoks said:
uhhhhh elaborate a bit more please? I got a mirror polish on all of my knives they cut waaaaay better than any other edge i had i feel like a regular edge "saws" more than cuts through
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As with many things, it depends on what you are doing and how you do it.

If you push cut everything, I would agree that higher polish level generally performs better. However, very few people push cut everything, and not all steels will support a high level of polish. Many of the modern "super" steels are rich in carbides and excel in slicing cuts (more like a sawing motion).

A lot of variables to consider here...and it has been considered HEAVILY in the past here (hopefully this time it will not spiral into a grudge match).

Different strokes, different folks. There is no one clear winner, there is only a best approach to a particular task or set of tasks...and even that may change over time as new materials become available.
 
In my experience (and I only did a serious study of this once) polishing finer than a 1 micron scratch will degrade the last bit of draw-cutting from an edge. If you're shaving with the thing, you'll notice a big improvement polishing beyond this level. For any kind of utility use, you'll notice the last of your edge's (already diminishing) ability to draw cut with good results and you might as well be pressure cutting everything. In my tests it was not subtle - the edge lost a lot of efficiency due to the very last of its grind pattern being removed. It did pressure cut better, but actually required more pressure to cut some materials because there was no advantage to lateral blade movement in the cut - no friction or minute changes of cutting surface angle.
YMMV.
 
I guess what I'm asking is if you sharpen to an 8-10k grit edge then strop how much more performance would you get going to say a 20 k grit then stropping? My gyess would be better push cutting but is it that noticable?
 
I hope no grudge match occurs, as I am very curious to hear what all you experienced sharpeners may have to add. I though I was ok at sharpening...but as I read more, I think I kinda might suck :).

polishing finer than a 1 micron scratch will degrade the last bit of draw-cutting from an edge. If you're shaving with the thing, you'll notice a big improvement polishing beyond this level. For any kind of utility use, you'll notice the last of your edge's (already diminishing) ability to draw cut with good results and you might as well be pressure cutting everything. In my tests it was not subtle - the edge lost a lot of efficiency due to the very last of its grind pattern being removed. It did pressure cut better
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I just ordered an EP and am considering getting the 6000 grit tape (supposedly 1 micron) and glass tape blank. After hearing about draw cutting vs. push cutting and the give/take of that balancing act...I might just stick with their 3 micron tape and strop on bare leather for my EDC.
 
Gunsnknives said:
I hope no grudge match occurs, as I am very curious to hear what all you experienced sharpeners may have to add. I though I was ok at sharpening...but as I read more, I think I kinda might suck :).



I just ordered an EP and am considering getting the 6000 grit tape (supposedly 1 micron) and glass tape blank. After hearing about draw cutting vs. push cutting and the give/take of that balancing act...I might just stick with their 3 micron tape and strop on bare leather for my EDC.
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It might be a good idea to experience for yourself what is best for you and your uses. I have developed my preferences after experimenting with bevel angles and edge finishes. I do have different preferences for different blade profiles and steels which to my mind do better with a certain set of bevel angle and edge polish.

Besides it's fun to experiment and discover what works for you and the never-ending search for sharpening knowledge is what draws a lot of us to the dark side. And even more, the Edge Pro is such an excellent laboratory for experimenting with angles and finishes that it would be wasted if you just went directly to one configuration for all your edged tools.
 
monk3yfist, i have sharpened knives with a coarse grit and had them treetop armhairs after using a medium grit polishing compound. i dont think there is a need to go real fine unless all you plan on doing is cutting hair and newspaper.
 
Gunsnknives said:
I just ordered an EP and am considering getting the 6000 grit tape (supposedly 1 micron) and glass tape blank. After hearing about draw cutting vs. push cutting and the give/take of that balancing act...I might just stick with their 3 micron tape and strop on bare leather for my EDC.
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Experiment away. The break point for my experiment was 2000 grit wet/dry and .3 micron polishing tape. Both edges were stropped on green CrO - presumably .25 to .5 micron. I've noticed the same reduction in efficiency in my tests following the Spyderco UF though to a lesser degree. In my experience draw cutting drops way off at higher than 800-1000 grit.

Try different stuff and do some cutting tests, just make sure you cut a range of materials.
 
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HeavyHanded said:
Try different stuff and do some cutting tests, just make sure you cut a range of materials.
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I agree with this advice, but would add that your "range of materials" should be limited to what you ACTUALLY cut in your life.
 
Darn you guys and this forum! Costing me more and more money :).

This morning as I lay awake, I was even thinking about how well the Endura in ZDP189 would do as a straight razor. With the incoming EP I was envisioning running the angle way down (not sure what the lower limit is, but I think it's around 9 deg each side?) just to see what happens.

Is it bad that I think of sharpening in my waking/sleeping moments?
 
Gunsnknives said:
Darn you guys and this forum! Costing me more and more money :).

This morning as I lay awake, I was even thinking about how well the Endura in ZDP189 would do as a straight razor. With the incoming EP I was envisioning running the angle way down (not sure what the lower limit is, but I think it's around 9 deg each side?) just to see what happens.

Is it bad that I think of sharpening in my waking/sleeping moments?
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Here is a ZDP Stretch that is a bit lower than you are discussing and I'd suggest that you could certainly shave with it (I have) but it is far from the ideal straight razor.
 

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Which compound do you use Richard? the green compound seems too fine.......or i only do few light passes on it.I used to over polish all my knives but as Richard J.says its only good for slicing newspapers and shaving! Jerry Fisk does the same when he sharpens and hes a legend!His method is what I like the most!Plain old Norton fine india stone work wonders!
 
i used to finish knives off with a super fine translucent white stone that would give me a mirror finish. a few guys complained about the edge sucking badly and going dull real quick. they told me to go back to what i was doing. i used a medium grit india stone and finished off the very edge with a ceramic stick. it would shave hair and cut just about anything out there that you needed to cut.

i use the medium grit white compound from lee valley which is what comes with the wheels. i was talking to ken onion a few weeks ago about sharpening. he said to get some tormek paste and try that on a coarse edge. he likes his paper wheels.
 
On the knives I use and sharpen, polished edges seem to give me the best performance. I look at it like this, a polished edge that is free of micro deformities will last longer than an unrefined edge with an already degraded edge.

Also, a lot of people confuse a polished bevel with a polished edge. On some of my knives, I have a mirror polished bevel, but I will leave the apex of the edge a little toothier, say 1200 grit. Some steels, like Vanax75, seem to hate a polished cutting edge - yet they excel with a polished bevel and a toothy edge.

When you get down to it, it's all personal preference. I honestly don't see enough of a disparity in performance to illicit such strong feelings on either side. I say do what you like, and leave it at that. :)
 
Extremely fine edges are not conducive to cutting a large variety of materials efficiently.

In many cases, they simply slide across material rather than cut it.

Even on my full mirror polished blades, I always go back with a fine ceramic stone to give the edge a very fine "micro serrated" edge.
 
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