What is the better goal when sharpening? I've heard and experienced when you've sharpened your knife on a well used whetstone with all kind of bumps in it, you're edge will look like this vwwvvwwvv under a microscope. With all these different sized and directioned spikes in it, similar like a T-rex jaw, it still gets the job done.
When a new knife or a knife with a "repaired" edge gets sharpened by a professional it should have an edge like this right ____________? Straight, without any spikes. Is it worth the effort to learn how to sharpen your knife like a professional knife maker?
You have opened a big subject. I'll try to contain myself to your questions. Firstly, knifemakers grind their edges with belt grinders, something few of us have at our disposal. They are the same machines they use for grinding the entire blade blank to its final shape. Some use whetstones to finish the edge but most are content with what the grinder produces.
When a stone becomes dished from wear, the edges it produces will also be dished. That may not be a problem but it is better to have a flat stone. Cooks who use waterstones grind the stones flat from time to time. There are flattening stones available for the purpose. Concrete blocks work pretty well also.s The striations to which you refer result from the abrasive grit, not the condition of the stone.
I've sharpened knives to a thin polished edge that, unfortunately stick to the cutting board which is inconvenient so you can oversharpen a knife as well. Unless you are a sushi chef, a medium or fine grit edge is all you need. A 1000 grit medium abrasive makes an edge as slick as it needs to be for most culinary purposes. Yes, under a microscope the striations caused by the abrasive are readily visible. Don't worry about microscopes, they aren't necessary or even used for knife sharpening.
The idea is to get the edge at as fine an angle as you can without having the edge collapse under pressure. For most kitchen knives 20 degrees per side is fine. 30 degrees for cleavers. Hard Japanese blades do just fine with 15 degree angles. The edge angle should be consistent from tip to tang and laterally straight. When the edge becomes laterally wavy from contact with the cutting board, you can use a steel to straighten it with a couple of light swipes.
So how do I do it? I use a guided manual sharpening system called the Edgepro. It holds the abrasive stones at a fixed angle so you can achieve that good performing angle consistency and the angle is adjustable. While I can get a blade perfectly sharp with a bench stone, the guided system makes it far faster and easier because I don't have to watch out for the angle or even think about it as I grind the edge.
I will leave you with a tip. As you grind the edge, it will eventually turn over to the side away from the abrasive. We call it a burr. You can feel the burr by resting the edge at an angle on your thumbnail. When you have a consistent burr along the edge, grind the other side of the blade. You will notice that, as you progress through finer grits, the burr will become smaller and sharper. When you have achieved the sharpness you desire you can remove the burr with a leather strop by pulling the blade against the strop rather than pushing it as you would using a bench stone for sharpening. Or you can ignore it. The burr is the guidepost for grinding the edge Learn how it feels and you will be on the way to being a great knife sharpener.
Traditional Japanese knives with thick blades and single bevels are another matter. We can get into that if you wish.
