So you bought a new knife and you used it a few times, but then you put it away with the tens and hundreds in your collection. It was cool, but didn’t seem to hold a good edge very long or stay sharp, but that old crapper fishing/hunting/kitchen knife you use all the time does. How come? The simple answer is because you don’t use it.
Commercial knives available today are some of the best in history, even the crappy cheap ones. The reason is the steels used in today’s knives are some of the best ever made. The computer controlled foundries are producing higher quality steel with less impurities in greater quantities and therefore cheaper than ever before. So even some of the really cheap crappy knives you pick up have pretty decent blade steel.
Why does my new knife suck though? Because of the grind. Check out this nice illustration at wikipedia. Almost every knife you buy that was mass produced will come with a #3 saber grind because it is the easiest and best grind for all around use that a machine can easily make. It has two precise angles, and blades can quickly be ground to a razor sharp edge. So blame the robots! There is nothing wrong with this, but from looking at the illustration you can see the edge is very thin and can easily be flattened or bent out of shape. Most people continue this grind shape on their knives because they use all manner of angled gizmos to sharpen them. Angled ceramics, electric sharpeners and things you pull along the edge are all designed to keep that straight angle on the blade and give you a razor sharp edge.
If you’re satisfied with this, great! keep doing what you’re doing. The only real difference is you will be sharpening more often, and your edge is more vulnerable to chipping, but you’ll have just as sharp a knife, that’s just as useful. If you want more out of your knife buy some type of whetstone. Before the usual exasperation, (OMG! How do I use a flat stone to sharpen things? There might be math involved!) let me assure you there is less math involved than there is with the other sharpening gizmos – it’s just the other gizmos have done the math for you. You will have to acquire some skill which will mean practice. I will admit I do still use the gizmos for quick stuff and kitchen knives. What you get with a flat stone is an eventual convex edge. That’s #6 on the above chart. The convex edge is just as sharp as the V or saber grind, but it is much stronger and will stay sharp longer, and be less prone to chipping. It’s all in the sacred geometry. OH NOES MATH! Relax, it’s only in the explanation. The convex edge has much more steel backing the edge. Remember from geometry class? Say it with me, circles are stronger than squares and triangles.
So how do you get one? If your knife came with an edge like that you’re in luck, as it was most likely hand ground. If not, you can do it yourself, and you don’t even have to work hard at it. How? Use a flat stone when you sharpen things. This is where we get rid of the math. Your human sense of angles is vague. You try to hold the precise angle on the whetstone, but due to human error you wont get it exactly right each time. You will however not quit until it’s sharp. Over time you will round the angle that the machine ground at the factory until it becomes convex. This happens a little even when you use the sharpening gizmos as long as you’re using them often. That’s why the old crappy bait knife and kitchen knife I mentioned earlier always seem to stay sharp.
My dad showed me how to use a whetstone when I was young and I’ve been practicing ever since. There are plenty of videos on youtube that show how to use a flat stone so I won’t go into that here. The problem is in the beginning when you’re not so good at it YOU WILL most likely scratch the blade. Start with a knife you don’t really care about the finish on until you get the hang of it. Once you get it down you’ll have no problems with scratching finishes. It just takes practice and best of all once you get the technique there’s nothing for you to do, just keep using the flat stone and you’ll get that convex edge. So get practicing!