Is polishing compound necessary on a leather strop?

[Lagrangian]

Something I keep noticing, when searching the web for 'answers' to many of the mysteries of steel, sharpening, abrasives, etc., is there are a lot of very scant, vague references to technical documents that might have more insight, but often one is required to purchase the doc as a whole, to read more. That gets me to wondering, and it wouldn't surprise me if some truly advanced methods or technologies exist, but may either be proprietary to a corporation or patent-holder ('trade secrets', in other words), and may not be readily available to the public at large. I used to work in the semiconductor industry and, in that sector, new manufacturing technologies were zealously protected by the companies holding the patents, and they were likely patenting new ones at the rate of thousands per year. Companies that manufacture tools, steel, abrasives and other technologies related to our 'hobby' here might not be sharing everything they know about materials & methods either. Assuming something really is a game-changer or takes it to a whole new level, I can't really blame the inventor for playing it close to the vest, at least until they figure out a way to get rich off of it (that's my cynical view of such things, anyway).

Hi Obsessed with Edges,

There are a LOT of extraordinarily advanced abrasion and polishing techniques, and I would expect many of them to be either patented, proprietary, or both. Here are just a few examples that I have heard of myself:

(1) Ion-Beam polishing is used to sharpen some diamond-coated razor blades until they are literally ten times (10x) sharper than conventional razor-blades. Conventional razor blades are sharp to about 0.4 microns, while these diamond-coated blades are ion-beam sharpened to 0.05 microns.
http://www.technologyreview.com/computing/25988/
http://www.google.com/url?sa=t&rct=...-oDgDA&usg=AFQjCNH31y8vOooTMt01DaDjb9NgmPtjmg
http://en.wikipedia.org/wiki/Figuring
http://en.wikipedia.org/wiki/Ion_milling_machine

(2) Diamond microtome knives are honed and polished until they are literally a hundred times (100x) sharper than conventional razor blades. Conventional razor blades are sharp to about 0.4 microns, but these diamond microtome blades are sharp to 0.005 microns. As you might expect, the cutting edge is accurately aligned with specifical crystal axes of the diamond. btw, you can buy one for only around $4k, and it comes with a free wooden box!
http://www.tedpella.com/diamond_html/diamondk.htm

(3) Computer chips have extraordinarily precise surface polishes, both before and during lithography. For example, in order to lay the layer of interconnects in some CPU's, the surface is first polished flat so that additional layers of interconnects can be applied. This polishing is extraordinary in that it does not damage the layers underneath, while flattening the surface.
http://www.research.gov/research-po...ardDetailEvent_rsr&awards_1_fedAwrdId=0620428
http://jes.ecsdl.org/content/138/11/3460.abstract

(4) Magnetorheological polishing: A magnetic fluid is used as a carrier-medium for abrasive particles, and is controlled with magnets. Being researched for ultra-precise and ultra-smooth polishing of optical lenses and mirrors.
http://www.opticsexcellence.org/SJ_TeamSite/RS_mrf.html

(5) X-ray telescope mirrors are polished until atomically smooth. For conventional materials, you can't get more polished than this.
http://www.mpe.mpg.de/xray/wave/technologies/mirror.php

(6) Special burnishing and polishing techniques were used to make the rotating spheres in one of the most precise gyroscopes ever manufactured.
http://einstein.stanford.edu/TECH/technology1.html

(7) Standard optical polishing of glass lenses is often done with cerium oxide. The polishing is both mechanical and chemical, and often the surface of astronomy mirrors are accurate to within 1/10th wavelength or better, with some optical flats being accurate to 1/60th of a wavelength of visible light. Visible light is around 0.38-0.74 microns.
http://www.edmundoptics.com/optics/...-100-single-surface-optical-flat-mirrors/2746

(8) Needles used in atomic-force-microscopy (AFM) and scanning-tunneling-electron-microscopes (STEM) can be as sharp as a single atom. I forget, but I think these are sharpened using ion-milling/ion-beam polishing.

Hope this was fun, if nothing else.

Sincerely,
--Lagrangian

 

[stitchawl]

Hi Stitchawl,

Thanks for your advice!
I didn't know what "shell cordovan" is, but I think I got it here:
http://en.wikipedia.org/wiki/Shell_cordovan

Sincerely,
--Lagrangian

That's it. Wiki got it right for a change. Well, right but a little confusing too. It's correct for 'shell cordovan,' but not quite for 'shell.' You're probably familiar with cowhide is divided for use; bellies, shoulders, sides, double shoulders, etc. Well, horsehide is sold in different cuts, such as butts, shells, culatta, strip, double horsefront, etc. You can see the locations here, and see one of the reasons why 'shell' cordovan is so pricey! The shells are pretty darn small!

Stitchawl

 

[stitchawl]

There are a LOT of extraordinarily advanced abrasion and polishing techniques, and I would expect many of them to be either patented, proprietary, or both. Here are just a few examples that I have heard of myself:
{Incredible sharpening stuff removed only for the sake of brevity. Amazing information!}

Lagrangian, I don't think you should have posted this stuff... Now we're all going to be trying to get our Kabars and CRKTs sharpened to .005 micron... This may lead to a LOT of, if not outright divorces, at least a lot of nights sleeping on the couch!


Stitchawl

 

[Lagrangian]

Hi stitchawl,

Thanks for the link showing the different cuts of leather. Very interesting, and good to know!
As for lots of sleepless nights on the coach, ah, I didn't mean to cause any of that.

Unfortunately, it is very unlikely that our everyday knives could be sharpened to 0.005 microns. The reason is that the sharpness of knives is limited by several factors, including the size of carbides and poly-crystalline grain-structure of the steel. At least it is for conventional sharpening methods.

You can think of trying to sharpen a wood knife by abrasion... It would be pretty darn hard to get the edge of the wood knife to be sharper than the size of a wood fiber. If you try to get the edge sharper, you are likely to simply tear out a fiber. It's more complicated than this, and I don't know all the metallurgical details, but that's the understanding I have. You can read more about it, with links to references, from an article that Cliff Stamp wrote. It includes some references to work done by metallurgist and knife-maker Roman Landes, as well as others.
http://www.cliffstamp.com/knives/articles/edge_stability_review.html

The reason that obsidian flakes can be sharp to 0.003 microns, is because glasses have zero grain structure. So a crack in glass can grow as a super-smooth surface all the way to the edge of a flake. And there is no micro-crystalline grain structure to cause roughness, to break-off, or to tear-out at the edge.
http://en.wikipedia.org/wiki/Obsidian

So this is why glass flakes (concoidally fractured obsidian), diamond microtomes, and diamond-coated razors can get so insanely sharp: They have no grain structure.

Of course, as a sharpening-nut wanna-be, I wish my knife were sharp to 0.005 microns! If I were rolling in money, I would buy one of those diamond microtomes just to experience how crazy sharp they are.

Sincerely,
--Lagrangian

 

[stitchawl]

You can read more about it, with links to references, from an article that Cliff Stamp wrote. It includes some references to work done by metallurgist and knife-maker Roman Landes, as well as others.
http://www.cliffstamp.com/knives/articles/edge_stability_review.html

I've been reading his stuff for years, going back to the days of Usenet newsgroups. He really did some fine studies.

The reason that obsidian flakes can be sharp to 0.003 microns, is because glasses have zero grain structure. So a crack in glass can grow as a super-smooth surface all the way to the edge of a flake. And there is no micro-crystalline grain structure to cause roughness, to break-off, or to tear-out at the edge.

I was a hobbyist 'Flint Knapper' and I'm here to tell ya, that stuff can get pretty darn sharp. We knapp flint, obsidian, etc., and even glass! When learning to knapp, we use the bottoms of glass bottles, which knapp just like obsidian. Thick table-top glass is actually lovely to work with, easier to sharpen than flints or obsidians as there are no flaws in it. And man... it gets sharp! In fact, one of the reasons I stopped knapping was I was getting little micro-cuts too often!

Stitchawl

 

[grizzled gizzard]

Wow Lagrangian, awesome post, man! As usual.

I'm going to keep an eye out for some thick glass to knapp as well, Stitchawl.

 

[stitchawl]

Wow Lagrangian, awesome post, man! As usual.

I'm going to keep an eye out for some thick glass to knapp as well, Stitchawl.

The bottoms of pop bottles and beer bottles are the most commonly used glass. But the recycle centers are reluctant to take back bottles without bottoms so be prepared to give up the the 5 cents deposit...


Stitchawl

 

[Obsessed with Edges]

(...) I was a hobbyist 'Flint Knapper' and I'm here to tell ya, that stuff can get pretty darn sharp. We knapp flint, obsidian, etc., and even glass! When learning to knapp, we use the bottoms of glass bottles, which knapp just like obsidian. Thick table-top glass is actually lovely to work with, easier to sharpen than flints or obsidians as there are no flaws in it. And man... it gets sharp! In fact, one of the reasons I stopped knapping was I was getting little micro-cuts too often!

Stitchawl

That revived a decades-old memory for me. About ~40 years or so ago, when I was a kid, a buddy of mine and myself used to go plinking with our BB guns in the open mesa near our neighborhood. Usually, cans and glass bottles were our favorite 'targets' to shoot at. One of the things we liked to do, was to shoot a BB sort of obliquely at the broken-out bottom of a soda/beer/liquor bottle, and sometimes it would chip out a circular, cone-shaped piece from the center of the bottle bottom. The heavier, thicker glass of large liquor bottles usually made the most impressive ones. We called the chipped out pieces 'cat's eyes', though I have no idea how that term originated. I hadn't thought of that in a very long time, until you mentioned knapping the glass from bottle bottoms.

 

[singularity35]

We also used broken glass to finish our homemade wooden tops when I was a kid. They were the sharpest edges around for us. When they get dull, we broke them again.