PERSONAL OPINION

Whetstone sharpening

What if I tell you that whetstone knife sharpening is the method that can provide you with the best results, much better than any machine sharpening? It may sound like a lot of effort, which it is at first, but after a fair number of attempts, it will be a no bigger deal than taking a shower in the morning, talking from experience. It takes much longer than a machine sharpening, hands down, but the result that you can get from sharpening on a stone is phenomenal.
I remember my first attempt. It turned out that the knife that was getting sharpened got duller than before! One of the issues was that I could not maintain a consistent angle. My hand motions were swinging the knife on the stone rather than keeping at a precise angle. That led to an uneven, wavy cutting edge. The practice helped me learn to maintain a certain angle that fits the type of knife I'm sharpening.

Each knife category has a type of sharpening. Let's take a chef knife as an example. Most European chef knives have a bulky bolster that continues into the finger guard. These knives work the best with the V-type of sharpening. Utility knives, another example, have a thinner, flexible blade that works the best with the high flat type of sharpening, so far and so on. I talked more about different types of sharpening in the Knife bevels article. Each type of sharpening requires an even angle across the whole edge, it cannot change to ensure proper cutting. Otherwise, it may lead to unpredictable knife behaviour cutting through foods.
In this article, we will be sharpening a knife that is in rough shape, while proving that whetstones is the way to go. Let's do it.
Side by side
This is what we are dealing with
After the cutting edge is shaped, we should continue sharpening using a 3000-grit stone
First of all, let's remove all chips from the cutting edge. It is possible to remove all the imperfections from the blade using a stone but using an electric grinder to shape a new cutting edge has approximately saved me about 30 minutes.
After the grinder, I bring both sides of the new cutting edge together on a stone, so I use a 1000-grit whetstone to start the process. Do not mistake a rough edge with a sharpened edge. A 1000-grit stone leaves a coarse edge that works like a serrated knife on a microscale. You would think that it is what we wanted, a knife that can cut, but if you stop sharpening after using a 1000-grit stone, it will get dull quicker than the knife would with a 6000-grit stone. The reason is that after the 6000-grit, the edge has a smoother finish that provides you with a good cut, and this is what we want. Also, a rough serrated edge would get duller faster because a burr on the cutting edge easily gets chipped off after each strike as the knife cuts through foodstuff. On the other hand, if a knife has a smooth finish, it would slide through the cutting product. You can see the burr in the picture and how the light reflects from the unjointed cutting edge.
I think that the optimal results achieved with a 6000-grit stone. A knife should not take more than 10-15 minutes to get sharpened if it is in good shape. So, why the window between 1000-grit and 6000-grit? Look at it this way: say, you have a set of five knives that you need to get tuned. This set has been used for 3-4 months, and it has a few minor chips on the blade and a U-shape edge on all five of them. A 1000-grit stone is a perfect start for that case because it would not be too aggressive to the blade, and it won't take off too much material from it. After the 1000-grit stone, you have a re-shaped edge with a burr.

To remove the burr and the scratches from the 1000-grit stone, you should switch to a 3000-grit stone. This step is to refine the edge and make it a clean V-shape. In the picture we can see that the cutting edge is much cleaner and has a smaller burr.
After that, a 6000-grit stone will get light scratches from the previous stone off and make the cutting edge smooth. Don't try to jump through a step, as you would spend more time removing the burr and scratches from the first step if you skip through the second stone. I have made that mistake before.
I have seen people go crazy up to a 10,000-grit tone and use leather to get a mirror-like cutting edge. But it requires too much time and patience to achieve such result. I do not think it is rational to do with a daily kitchen knife. Maybe with a collection knife.

See that light reflection right on the cutting edge?
How can I say that is a knife or scissors sharpened? The answer is in a reflection. I discovered that by holding a knife vertically, edge up, under a lamp, under a closer eye, we see if the cutting edge has a burr or a chip. This way, we determine if we need to continue sharpening. Any chips or burrs will reflect the light from the lamp and reveal every imperfection of the cutting edge. It works the best if you use a lamp with 6000k and cooler light colors. Warm light colors are not as visible. I assume the blueish light reflects better from a metal surface than a warm-colored light.
If you ask me to choose between a synthetic stone and a natural stone, I pick the synthetic option. The reason is that the synthetic stones are ready to be used out of the box. They are easier to maintain, and you do not need to guess the grit number, as each stone has a mark on a side. We talk more about the difference between natural and synthetic stones here.

I have tried quite a few methods of sharpening in terms of hand movements: strikes from the center to the side of the stone; one-way and both ways strike; I have tried to split the cutting edge into sections and work on each separately; I even tried left-hand sharpening (miserably failed on that one). Of course, each method leaves a specific set of scratches that facilitates the shape a whetstone gets. I believe I have made enough mistakes and wrong decisions in this craft, so I have something I can share with you.

When I take a new stone and visually separate it into two sections. They are upper and lower sections. The upper section is for the right side of the edge, and the bottom is for the left side of the cutting edge. I try to make the same movements on each side, making the edge identical from both sides.
Practice, practice, practice. You will get there.
Here are some tips:

The right angle is the key. You can have a perfect cutting edge on one side, but the other is too high/low. Eschew it due to uneven cutting pace after sharpening. It may even seem that some parts of the knife feel sharper than others.

As you work with a new stone, remember that each knife strike shapes it. If you see that certain parts of the stone get worn quicker than others, you can try to adjust the positioning of your hands and the knife. You should get a clean U-shape without any low or high spots. I do not utilise any tools to get a stone resurfaced, as I believe it is a waste of the stone material that could be used for sharpening. Knife sharpening is an art. Practice and patience get it perfect, just like everything else.