Thread: Fin: fact or fiction?

The first one was better. I have sigmoid rumbling below the beltline and it probably is caused my too much gas so they may be on to something after all.

Originally Posted by tpoof

Sorry there Bart, Its just that particular statement was way over my head!
I can you see you believe in what you are saying, but in my observation under microscope power mostly 100 power to 450 power I can see no fin and especially no burr of any sort being formed by honing or stropping. (straight razor)
no plastic deformation or debris deposits...
sounded funny is all... sorry if I offended...
I use a burred cabinet scraper for doing my woodwork projects ink:

Tpoof, if you didn't intend to hurt me, I shall not feel that way.

I am more than aware that you don't need to know anything about this stuff, in order to put a great edge on a razor. You don't need to know anything about the Maillard Reaction, Strecker Degradation and Caramelisation to make a decent cup of coffee, but it sure is interesting to dive into the exciting world of organic chemistry. http://www.jimseven.com/2006/06/20/m...aramelisation/
If that qualifies me as a nerd, so be it. Former barkeepers don't care about such qualifications.

Now, about the core of the matter: of course you don't see any differences at the edge of a razor under magnification. For starters, there's the issue of optical resolution. With optics that regain some depth of field, such as present in a decent stereo microscope, there is a serious limitation of the smallest objects that can be seen. I quote Wikipedia: "Great working distance and depth of field here are important qualities for this type of microscope. Both qualities are inversely correlated with resolution: the higher the resolution (i.e. the shorter the distance at which two adjacent points can be distinguished as separate), the smaller the depth of field and working distance. A stereo microscope has a useful magnification up to 100×. The resolution is maximally in the order of an average 10× objective in a compound microscope, and often much lower."
For this reason, most of us can't discern objects smaller than 1 micron, regardless the magnification factor. Few of us have access to a Scanning Electron Microscope, a device that offers resolution far beyond that of optical microscopes.
I have posted a picture of a honed and stropped straight razor, as observed with a SEM, by professor Verhoeven, earlier in this thread. Guess what? It does show a bur. It's even folded over a bit, probably especcially for us, so we could end all discussion. http://straightrazorpalace.com/advan...tml#post301950

Another thing that all SEM pictures of highly polished edges always strikingly display, is something they don't show... A sawtooth pattern at the very edge. It's never there, and still, it should be there, at least if we presume that honing is only abrasion. If that was true, the scratches, left by the hone, would end in a jagged line. And yet, they do not. We always see a fluent line. According to Verhoeven, abrasion is not the only contibuting factor to honing. He quotes two other factors: debris deposit and plastic flow. The first does exactly what it says: honed away steel piles up, inside scratches and on top of the original steel. It happens mostly in the honing direction, but not exclusively. The second is a bit more difficult to understand: it's they same process that makes steel bendable and rollable. This is called "plastic deformation" Elastic/Plastic Deformation If the same principles are only occuring on the surface of a steel object, they are called "plastic flow".
Burs exist of steel that was shaped by one or both of those two non-abrasive factors. They have to, because abrasion cannot allow something to grow. Debris deposit and plastic flow can.
I don't think such steel looks different. If you look at the burred edge of a cabinet scraper under magnification, you can't see any difference between the bur and the original steel, other than the bur being a part that's bend over. For those that not know about "sharpening" scrapers: the scraper is first honed to a perfect 90° corner, a tool called a "burnisher" is used to push the 90° corner into a bur shape. It requires surprisingly little force.

My point is that the final part of the edge is much more formed by plastic flow than by abrasion.
Here's a quote from another document: http://www.public.asu.edu/~smurshed/...operations.pdf
"Buffing is a smoothing operation which is accomplished more by plastic flow of the metal than by abrading. The abrasives are generally finer than those used in polishing and instead of being firmly cemented to the wheel are merely held by a "grease cake" or similar substance." That sounds very similar to pasted stropping to me. Scientific studies about the durability of plastically deformed steel exsist. I have linked to one in this post: http://straightrazorpalace.com/basic...tml#post298259

I think stropping on leather is more about pushing (actually drawing or folding) the edge (back) into shape than it is about abrasion. In my mind, I think about the part of the edge that can be influenced by stropping as "the fin".

I hope you had fun reading this. I really do, because otherwise I fear you might be asleep by now.
Bart.

Tpoof, if you didn't intend to hurt me, I shall not feel feel that way.

No harm intended friend, sometimes I just like to get a rise out of a poster for more info..

I hope you had fun reading this. I really do, because otherwise I fear you might be asleep by now.

Whooo Hoooo.... Now there's a mouthful!!

and a very interesting mouthful indeed!
Excellent post!

" I once was blind but now can see"
information appreciated!

Another thing that all SEM pictures of highly polished edges always strikingly display, is something they don't show... A sawtooth pattern at the very edge. It's never there, and still, it should be there, at least if we presume that honing is only abrasion. If that was true, the scratches, left by the hone, would end in a jagged line. And yet, they do not. We always see a fluent line. According to Verhoeven, abrasion is not the only contibuting factor to honing. He quotes two other factors: debris deposit and plastic flow. The first does exactly what it says: honed away steel piles up, inside scratches and on top of the original steel. It happens mostly in the honing direction, but not exclusively. The second is a bit more difficult to understand: it's they same process that makes steel bendable and rollable. This is called "plastic deformation" Elastic/Plastic Deformation If the same principles only occuring on the surface of a steel object, they are called "plastic flow".
Burs exist of steel that was shaped by one or both of those two non-abrasive factors. They have to, because abrasion cannot allow something to grow. Debris deposit and plastic flow can.
I don't think such steel looks different. If you look at the burred edge of a cabinet scraper under magnification, you can't see any difference between the bur and the original steel, other than the bur being a part that's bend over. For those that not know about "sharpening" scrapers: the scraper is first honed to a perfect 90° corner, a tool called a "burnisher" is used to push the 90° corner into a bur shape. It requires surprisingly little force.

My point is that the final part of the edge is much more formed by plastic flow than by abrasion.

THAT alone was worth the price of admission!
gives my knowledge of whats happening just a little more clarity

But there's more..

"Buffing is a smoothing operation which is accomplished more by plastic flow of the metal than by abrading. The abrasives are generally finer than those used in polishing and instead of being firmly cemented to the wheel are merely held by a "grease cake" or similar substance." That sounds very similar to pasted stropping to me. Scientific studies about the durability of plastically deformed steel exsist. I have linked to one in this post: http://straightrazorpalace.com/fo...tml#post298259

I think stropping on leather is more about pushing (actually drawing or folding) the edge (back) into shape than it is about abrasion. In my mind, I think about the part of the edge that can be influenced by stropping as "the fin".

Once again, Thanks Bart for taking the time to make the unclear a little more clear! appreciated!

Some of you guys need to find a woman...

Originally Posted by kelbro

Some of you guys need to find a woman...

One who shaves her legs with a straight razor.

Originally Posted by kelbro

Some of you guys need to find a woman...

I already have enough "debris deposits"