How low is it practical to go in microns for stropping?

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yepimonfire

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Nov 7, 2013
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Alright so finally got the chance to strop all the way down to 0.1 microns, and it does indeed take on a new level of insane sharpness. Next step is .05 microns and .025 microns, at least that is the absolute smallest i've found manufactured. Can an edge even get any thinner/refined past .1?
 
How are you getting that small of a micron to strop on? film?

And can you share how you strop or what are your stropping steps? I suppose you can start from the last stone that you use just before stropping.
 
Paste. And I leave off an 8k stone (3 microns) and start stropping with 2 micron paste, down to 1 micron, .5, .25 and finally .1 about -200 passes on each strop and on the 8k stone
 
yepimonfire said:
Alright so finally got the chance to strop all the way down to 0.1 microns, and it does indeed take on a new level of insane sharpness. Next step is .05 microns and .025 microns, at least that is the absolute smallest i've found manufactured. Can an edge even get any thinner/refined past .1?
Click to expand...

I think that below 0.25 micron, you can improve the polish of the bevel, but not necessarily increase keenness.
 
yepimonfire said:
Paste. And I leave off an 8k stone (3 microns) and start stropping with 2 micron paste, down to 1 micron, .5, .25 and finally .1 about -200 passes on each strop and on the 8k stone
Click to expand...

What strop material are you using?
 
yepimonfire said:
Alright so finally got the chance to strop all the way down to 0.1 microns, and it does indeed take on a new level of insane sharpness. Next step is .05 microns and .025 microns, at least that is the absolute smallest i've found manufactured. Can an edge even get any thinner/refined past .1?
Click to expand...

Are you just exploring possibilities or aiming for something with your edge? How polished is the edge on your carry knives? Not being snarky, just curious.
 
Wow .025 micron would pretty refined! Is this for a razor?

In reality, with a knife you're never really going to need anything that refined, unless you're doing something highly specialized with the knife. Also, an edge won't stay refined to that level for very long during most cutting situations. You asked how low is practical? Commercial razor blades have about a .4 micron edge. To go any finer than that would be overkill IMO. Personally I wouldn't go past 1 micron for any sort of a regular knife. A straight razor would be a different case of course.

However, if you're doing this purely for the fun of it to see what an edge is like at .025 micron then by all means go for it!

-mike
 
ToddS said:
What strop material are you using?
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I've used both denim and leather. I think denim does a better job at keeping the angle flat.
singularity35 said:
Are you just exploring possibilities or aiming for something with your edge? How polished is the edge on your carry knives? Not being snarky, just curious.
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This is on my carry knives and kitchen knives. I can peel ripe tomatoes, slice homemade bread with push cuts without smashing it, and my carry knives go through any material I cut like butter. It's worth the time and effort IMO.
 
yepimonfire said:
Yeah but a .1 micron edge can be obtained with 1 micron stropping or a 16k waterstone.
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I understand going to high grits, I once did it myself and loved every minute of it. But, you don't need an 16k edge to shave. When I sharpen Razors I finish with a Naniwa Snow White 8k followed by 10-20 passes per side on a loaded denim strop. I use chromium oxide or Mothers mag polish (don't knock it till you try it) for compounds.

As for practicality,

From about 8k on up you have diminishing returns on your edge retention and cutting ability.
 
yepimonfire said:
This is on my carry knives and kitchen knives. I can peel ripe tomatoes, slice homemade bread with push cuts without smashing it, and my carry knives go through any material I cut like butter. It's worth the time and effort IMO.
Click to expand...

I used to polish everything before too but it gets old fast when you have to cut more than just a little everyday. Then I carried one that was polished and one that was lower finish. Hehehe.

Anyway enjoy what you like. :)
 
ToddS said:
I believe shaving requires an edge width of around 0.1 microns.
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I've shaved (my face) with a paring knife directly off a 4k water stone. Granted it wasn't the cleanest possible shave, although that may have had to do with the fact that it was the first time I'd used anything other than a safety razor. Oh and Dr. john d verhoeven (a well respected metallurgist and scientist) at Iowa state university measured commercial razor blades to have an edge radius of .35-.45 micron; he's done a lot of very interesting research in the knife making and metallurgy fields actually. Not saying a .1 micron or less edge wouldn't shave even better, but you can certainly shave with a .4 micron edge.
 
North Arm Knives said:
... Oh and Dr. john d verhoeven (a well respected metallurgist and scientist) at Iowa state university measured commercial razor blades to have an edge radius of .35-.45 micron; ....
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There is a reference in the Verhoeven manuscript you are referring to:

[4] J.F. Sackman, A Close Shave, Physics in Technology, vol. 9, 208-213(1978)

That paper describes the manufacture of DE blades and contains the following quote:

"The tip radius is measured absolutely by reflection or scanning electron microscopy. Generally it is about 50 nm."
 
I was referring to page 7 of this document; it refers to both a straight razor and commercial blade from a Gillette razor http://www-archive.mse.iastate.edu/fileadmin/www.mse.iastate.edu/static/files/verhoeven/KnifeShExps.pdf

I'm just answering the OP's question; of course it is my opinion and everyone is entitled to their own ;). Also: if cutting ability is the concern one has to start looking at edge and bevel angles as well as they play a significant role.

ToddS said:
There is a reference in the Verhoeven manuscript you are referring to:

[4] J.F. Sackman, A Close Shave, Physics in Technology, vol. 9, 208-213(1978)

That paper describes the manufacture of DE blades and contains the following quote:

"The tip radius is measured absolutely by reflection or scanning electron microscopy. Generally it is about 50 nm."
Click to expand...
 
North Arm Knives said:
I was referring to page 7 of this document; it refers to both a straight razor and commercial blade from a Gillette razor http://www-archive.mse.iastate.edu/fileadmin/www.mse.iastate.edu/static/files/verhoeven/KnifeShExps.pdf

I'm just answering the OP's question; of course it is my opinion and everyone is entitled to their own ;). Also: if cutting ability is the concern one has to start looking at edge and bevel angles as well as they play a significant role.
Click to expand...

All of my carry knives have edges between 15-18 degrees. I feel this is a good compromise between cutting ability and edge stability. Kitchen knives are 20 degrees but the blades are already thin and are too soft to support much thinner. I did notice that polishing them down to .5 micron last time increased the time to needing sharpening from 1 week to about two. Previously they were being finished on an 8k stone at 3 microns.
 
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