Count Steer wrote: ↑Wed Aug 30, 2023 7:52 pm
Next question....what does a leather strop do to a blade edge.....?
There are effectively three stages in sharpening an edge.
Creating the bevel
Polishing the edge
Stropping
The bevel is set by the factory to complement the steel type/hardness, thickness of the blade and its intended purpose. Typically you will have a bevel on both sides which meets at the cutting edge. More rarely you might have a single bevel, such as a Chinese Chef Knife which is flat (ish) on one side with a single angled bevel on the other. Yes, you could write a book on this topic so I have skipped about ten pages of disclaimers here...
You can only sharpen a blade so much before it will be so thin it will bend, like tinfoil. Depends on the material and the bevel angle but since you are allowing two angles to meet, inevitably the cutting edge wanders off to infinity. Reality gets in the way here (there's no such thing as infinity!) and long before then the very edge of the blade will form a burr. The super thin edge will simply fold over.
Once the bevels meet and start to form a burr, you want to start polishing the edge with ever finer stones. You have reached the limit of your blades geometry to hold an edge. Polishing is important because the lovely shiny bit means the surface is so precisely aligned, even light bounces off it in the same direction. It will still form a burr and it is vitally important to maintain that and not try and grind it off. The burr is telling you the edge is as good as it gets where the bevel meets thin air.
Stropping is where you remove the burr which should be a continuous thin wire representing the ultimate ability of the blade to hold an edge. Rubbing the blade along a strop causes the burr to fold over to the other side. Rubbing the other side causes it to fold back. Keep doing that and sooner rather than later, the wire edge will suffer from fatigue and detach leaving you with the ultimate thinness of edge possible.
Stropping does also help with the polish but is not how you achieve a polished edge. Likewise, using a "steel" will strop the edge by flexing the microscopic contour alternately one side then the other to keep the edge keen. I think it is more like "burnishing" which realigns any imperfections and also work hardens the cutting edge. I believe the most effective way to strop the edge with a steel in between "sharpening" is to apply as much pressure as you dare with as much speed as you can muster consistent with removing as few fingers as possible.