It is largely accepted that you should pull a knife but there are instances when pushing is better. It really depends on the type of sharpener you are using.
You should push the sharpened edge toward/across the stone,not pull it backwards. Often the reason knives seem dull is because the microscopic edge of the blade has curled over on itself (a kitchen steel corrects this and is often overlooked in favor of unnecessary sharpening).
Using the Wrong Pressure or Angle
It's important to maintain a constant angle when sharpening and to also make sure you're applying the right amount of pressure. Too much, and you could end up with damage to your knife. Not enough, and it's not going to get sharp like you want it to.
It's crucial not to sharpen your knife too frequently or apply excessive pressure, as this can cause the blade to become thin and brittle.
Sharpening Angle Too High
Essentially, if you are working at too high of an angle, you may be blunting your edge. In practice, an angle that is only slightly too steep will not dull the edge. Only very high angles will create edges that feel dull.
Begin honing: Gently pull the knife down and back across the sharpening steel, going from the heel to the tip of the knife. Repeat: Once you've begun, repeat this motion five to ten times. Change sides: Switch to the other side of the blade and steel, and repeat the same motions.
While some stones – like those made of diamond or ceramic – can be used dry, they still usually benefit from a little water. Soaking the whetstone is important because it helps protect the stone from damage and wear. Sharpening your knives with a dry stone won't hurt the knife, but it will damage the stone over time.
Even the adjustable ones are not well suited to all knives. Electric pull through sharpeners remove way too much metal and shorten the life of your knife by years.
We recommend 6–8 pulls through the sharpener (tip up). If you need that extra degree of sharpness, polish the edge with a few strokes back and forth.
3/8 pitch uses 7/32 file. .
To sharpen your knives at home, you can use an electric sharpener or a whetstone (also called a sharpening stone). Electric sharpeners require little effort on your end, but stones are generally the preferred choice since they're gentler on blades, relatively inexpensive, and easy to use.
The file will cut away unwanted metal and leave a sharp edge sufficient to cut down trees and branches. Files only cut on the push stroke. Don't apply any pressure on the return, or pull, stroke. Pressure on the return will shorten the lifespan of a file used on metal.
Over-sharpening a knife can actually damage the edge and make it duller. It's important to sharpen a knife only when it needs it, and to sharpen it to the correct angle.
Most pros would agree that pulling the blade edge across the whetstone produces the best results. Not only will it bring the knife to its sharpest but it's also a much more effective way to remove chips and imperfections from the blade.
Common mistakes include twisting, pressing down or pausing the stroke of knives as you pull them through the sharpener slot. This can cause oversharpening (the loss of too much metal) or result in an uneven edge.
So what's the difference between honing and sharpening? Sharpening removes material from the blade to produce a new, sharp edge, while honing keeps the blade sharp by pushing the edge of the knife back to the center.
Short answer is whatever feels comfortable and works for you. I tend to do back and forth while gradually moving up and down the blade. On my cheap utility knives, this works fine all through the grits, then I finish with edge leading on the steel.
The answer is fairly simple. Yes, old knives can be sharpened as long as they are in okay shape.
Never cut on glass, ceramic or countertops. Those surfaces are harder than a knife's edge and will quickly dull the blade. It's what you cut on that dulls knives, not what you're cutting.
A sharp knife has lesser surface area than a blunt one. So, a sharp knife applies a greater pressure when used for cutting. This is why it cuts better.