Re: How to obtain a mirror edge?

[Jende Industries]

Thanks for the answer Leo! So do you think that the harder and high-tech steels like ZDP-189 are better with diamonds, and the more conventional steels are better with water-stones? Or is it more complicated than that?
Doug

Thanks for the intro, Leo! B)

Basically, you can make it as easy or as complicated as you like! :woohoo:

The grit comparison is by microns, which is the most mathematically correct way to present them without too much confusion. The size of the particle equals the size of the scratch.

Well, yes, and no. You need to take into account the friability (rate of break down) of the abrasive and binder, the action of the paste/swarf/slurry, if any, and the biggest variable – technique.

Technique first – heavier pressure is good for stock removal since it pushes the abrasives deeper into the steel, but light pressure is best for obtaining the best finishes that won’t cut through the ever thinning edge of the edge. What is heavy and what is light has some defining parameters, but is ultimately different for everyone.

Action of the paste/swarf/slurry – Diamond plates are subjected more to wear-down meaning that diamonds start off with sharp jagged and pointy edges that cut aggressively. For simplicity, imagine the diamond is in the shape of a pyramid, the tip of the pyramid is sharp and pointy, but as the diamond wears, the pointed area becomes wider, with a larger surface area as time passes that doesn’t cut as deeply. This is advantageous on finer grits. The dust from sharpening will also clog the surface on the plates, making less of the abrasive stick out, therefore slowing down the action as well while making it perform at a finer grit. The WEPS ceramic stones follow this same premise, only without diamonds.

Diamond paste is a different beast – it has the freedom to roll around and scrub the surface more than to scratch at depth, like the fixed diamonds on the plates. In other words, the pastes are “less” aggressive, and are better suited for polishing surfaces rather than stock removal. That’s a basic answer to why the higher grit diamonds are in paste form. On leather, the softness allows for a cushion that will round the edge of the edge over, but on something a little more solid, like balsa, the pastes are more aggressive.

Choseras work on several levels – They start off using the actual grit to scratch, but as this happens, abrasive and binding agent gets released and mixes with the abraded steel particles and breaks down, forming a paste. This paste, when worked correctly can actually produce a finer grit edge than the number on the stone. Also there are burnishing effects from the metal in the paste scratching the knife’s edge, creating a shinier surface. The binder is also a softer abrasive, which tends to “polish the grooves”, and adds to the smoothness of an edge.

Shaptons are somewhere between the Diamonds and Choseras – they have a hard binder which scratches deeper, but they don’t load up as readily (in fact, using them clean is the best). The abrasive does not get released, and there is no interaction with the binder, which leaves perfect little scratches all lined up in a row, but without polish to make it “smoother”.

SO….

Diamond plates tend to make edges that are rather toothy and somewhat serrated. They pass hair cutting tests because the grooves cut into the edge are clean due to no breakdown. These edges are more aggressive.

Diamond pastes will still give your edge of the edge little serrations, which make it more “toothy”.

However when you switch over to Choseras, you still get some serrations due to the large grit size breaking off the bits of the thinning edge, but the overall surface is much more consistent. These edges are smoother.

Shaptons abrade things without polishing, so you get a very cleanly defined edge with grip.

The WEPS ceramics are similar to the Shaptons, but because of the loading up, will tend to polish the grooves more, leaving a clean, but not necessarily perfect edge.

Here’s a progression I did[/url] using the stock WEPS and the Choseras. You can see the differences between the diamond scratches (which are still good, mind you!) and the Chosera.

Here’s one using the WEPS 600 and the Shaptons[/url]. You can see the differences between the Choseras and Shaptons here (lighting is different, though.)

I hope this helps!
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