Historically, there are three broad grades of Japanese sharpening stones: the ara-to, or "rough stone", the naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone, the nagura, which is not used directly. Rather, it is used to form a cutting slurry on the shiage-to, which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". As an indication, ara-to is probably (using a non-Japanese system of grading grit size) 500–1000 grit. The naka-to is probably 3000–5000 grit and the shiage-to is likely 7000–10000 grit. Current synthetic grit values range from extremely coarse, such as 120 grit, through extremely fine, such as 30,000 grit (less than half a micrometer abrasive particle size).[citation needed]
Manual sharpeners fall into two basic categories: those that use a V-shaped cutting notch, often made of ultrahard tungsten carbide, to carve a new edge onto a blade, and those that use fixed or rotating abrasive elements (either an abrasive ceramic or diamond-impregnated steel) to grind a new edge. In general you get what you pay for with both kinds. Cheap models under $20 get a lot of complaints about sharpening performance, ergonomics, and durability. Move into the $40 to $50 range, and you begin to see more solid results. The cheap V-notch sharpeners, in particular, get terrible marks from most knowledgeable reviewers; such models remove huge amounts of metal, rapidly wearing knives into toothpicks, and they leave uneven edges that cut poorly and dull quickly. (I used one of these for about a week in the ranch kitchen and can attest to their awfulness.) However, as you’ll see below, when done right a V-notch sharpener is an attractive option.
After you have completed a few passes over the stone on both sides, you can move to the final stage. This time it is P1 pressure, just enough pressure for you to control the knife. Ensure your stone is wet and now repeat the motions but with very very light pressure. You really need to focus here and ensure you are reaching the edge of the edge and again, just a few sweeps on both sides of the knife.
Edges lose their sharpness for the very purpose they cater to. Cutting acidic fruits and vegetables like lemon, tomato causes corrosion in the blades. Knives are often used to accomplish tasks they’re not meant to perform, like scraping or opening tin cans. Blade buckling is also a very common kind of damage your knife faces every now and then. It happens due to slicing items heavier than the knife itself or crushing ice. Keeping the knife in high temperature or washing it with harsh chemical based detergents also has havocking effects on the sharpness. Taking proper care of your cooking combat hunting knife is the only way to prevent it from fraying. Always select a suitable knife for the task, avoid heavy wooden cut boards and wash it immediately with cold water right after using.