This article is not about how to sharpen a knife, check this article instead, but briefly, a coarse stone is critical, it has the potential to raise a Burr quickly and make a dull knife sharp quickly. The correct use of pressure enables us to form a burr, remove the burr and then do some coarse stone refinement and thus create a very sharp knife. This sensation is motivation, it is a confidence builder and will enhance your sharpening experience, so believe me when I say that a coarse stone is your first priority. I recommend a 400, 600 or 800 grit. After that, depending on the knives you are sharpening strive to obtain stone combination, such as a 400 – 1,000 – 5,000 grit three stone combination is going to allow you to achieve knives sharper than most people have ever seen.
When attempting to choose a whetstone for sharpening your favorite knife, the number of choices can be mind boggling. In fact, sharpening stones are divided into four distinct categories consisting of natural whetstones and manufactured whetstones which, in turn, are divided into two other categories consisting of oil stones and water stones. Then, there are numerous different varieties of natural whetstones consisting of several different materials that are quarried from different places around the world as well as several different types of man-made whetstones!
Over the course of two days I re-sharpened nearly a dozen old blades, including removing the secondary bevel on an old stainless Ontario saber-grind Navy diver's knife, convexing the edge on flat ground 1095 Schrade 55 that also came with a secondary bevel, and fixing a broken tip on an old Kershaw folder. These stones made quick work of the Schrade and Kershaw. Both had completely new edge geometry within 30 minutes apiece. The Kershaw looked like-new, as if the tip had never broken. And the Schrade cut much better than it's secondary bevel would previously allow, regardless of how sharp I got it with a ceramic rod and strops. The Ontario took a little more work, as it had been abused a little the last time I'd held it, over 25 years ago and was as dull as a case knife - one of the reasons I decided to go ahead and do a full saber grind - well, a slightly convexed saber, I suppose would be more accurate. But within under an hour of using the two stones and a couple leather strops (one with black compound, another with green), the Ontario was shaving sharp again too.
Sharpening on the other hand is reupholstering the furniture or telling the hair stylist to give you a new look. Material is going to be removed from the edge of the blade. There’s no way around it. How much is removed will be a function of just how dull the knife has become or whether you’re sharpening to compensate for a chip in the edge or because the tip has broken off. If your knife is not damaged and you have it sharpened twice a year very little material will be removed each time, yet it may still be enough for you to notice just by looking carefully with the naked eye.
Your task as a sharpener is to remove that fatigued metal and expose the steel underneath, the fresh strong steel and bring side A and B of the knife together at the Apex precisely, sounds easy doesn’t it? Like peeling a layer off and having a fresh start, over and over. Of course there is much more to it than this but in very basic terms, you want the abrasive properties of the water stone to abrade the fatigued metal away, like an eraser.
Whichever method you choose, be it a waterstone (also known as a whetstone), or a pull-through (either V-shaped or ceramic wheels) it's important to regularly hone your knife with a honing steel, which we'll also cover below. You'll be pleased to hear that you won't have to reach for the stones too regularly – once every two or three months should suffice.
Different knives are sharpened differently according to grind (edge geometry) and application. For example, surgical scalpels are extremely sharp but fragile, and are generally disposed of, rather than sharpened, after use. Straight razors used for shaving must cut with minimal pressure, and thus must be very sharp with a small angle and often a hollow grind. Typically these are stropped daily or more often. Kitchen knives are less sharp, and generally cut by slicing rather than just pressing, and are steeled daily. At the other extreme, an axe for chopping wood will be less sharp still, and is primarily used to split wood by chopping, not by slicing, and may be reground but will not be sharpened daily. In general, but not always, the harder the material to be cut, the higher (duller) the angle of the edge.
A: Like cars, knife sharpeners run the gamut from basic to luxury and like cars the price can vary from extremely affordable to more than some people might want to spend. You can get a high quality sharpener that will put your knives through a 2 or 3-stage process which will result in an incredibly sharp edge for less than $20. Or you can buy a mechanical sharpener that will produce a virtually flawless edge for $200+.