19

I have a knife and a whetstone. One side of the whetstone is rough and the other is finely grained.

I occasionally sharpen my knife but I'm not 100% clear if I'm using it correctly. I normally move the knife in a circular motion trying to hold it at an angle.. o_O

I usually use the rough side first then polish it with the finer side.

Is this correct? What is the best technique for knife sharpening in general?

  • 2
    It depends a bit of the grain sizes of the stone, whether you need the rough side at all. Basically such two-sided stones often come in two versions: one with a rough and a semi-rough side (grain sizes around some hundred grit) and one with fine and super-fine side (grain sizes in the thousands). With the rougher version, the rough side is normally only needed if the blade edge was damaged and has to be rebuilt by grinding bigger amounts of material until it is free of notches. – Benedikt Bauer Dec 4 '14 at 11:17
  • I'm not sure TBH @BenediktBauer. I bought the thing years and years ago. Is there anyway to tell? – user2766 Dec 4 '14 at 12:05
  • 2
    If you rub some metal over the roughest stone, the metal will have scratches that can easily be seen with the bare eye. To see the scratches left by the semi-rough side you will have to look very carefully, maybe with a magnifying glass. Both of them will make some scratching noise when worked with a metal. With the fine and super-fine one will at first glance not guess that it is able to do any harm to a metallic blade. Their noise is more dull, like rubbing two very smooth surfaces on each other. – Benedikt Bauer Dec 4 '14 at 12:19
  • It's a whetstone. Make sure you use some oil! – Unknown Coder Dec 4 '14 at 16:46
16

My advice is to always use the entire length of the the stone, to make sure wearing is even, and it's easier to be slow and steady.

Also, some good information on cooking.SE.

How often you sharpen depends on how often you use them and the type of steel. I use Globals and Mundials and the Globals require much less sharpening Mundials.

Here's a video from Chefs Armoury https://www.youtube.com/watch?v=0TPDgdo7jfM

1. Prep your stones

Depending on what stones you use, you may need to soak or not. I use the Naniwa stones that just need to be wet and don't require soaking. I keep a spray bottle for this. I use 400, 1000 and 3000 stones.

2. Make sure your stone is flat

You want a flat stone so that the angle between your knife and stone is stye same along the entire length of the stone. If your stone has a curve in it, get it flattened first. If there is a noticeable curve, ask a professional to flatten it. After this, maintaining a flat stone is easy.

3. Decide your angle

Usually 15-20 degrees. I find the Japanese knives are usually at around 15 degrees and European knives are around 20 degrees based on a bit of trial and error. You'll know if your angle is too low since you won't make progress after a few strokes.

4. Holding the knife & stroke

One hand on the handle (of course) holding the knife at the desired angle. The other hand, fingers on the flat of the blade. Wrists straight. The sharpening stroke is when the knife moves away from the edge.

So if the edge is facing towards you, push into blade as you push your blade away but release the pressure as you pull the blade towards you.

If the blade is facing away from you, push into the blade as you pull towards you and release as you push away.

Make sure you maintain the same angle on both strokes and always use the entire length of the the stone. If you only use part of the stone, that area wears away more quickly and you can't be sure of the angle.

5. Sharpening

Start with the coarsest stone. Pick a side, say edge facing towards you. I start at the tip of my knives. The tip is usually curved, so your hand position changes slightly. After a few strokes, move down the edge and take a few stokes. Keep doing this until you have done the entire edge applying water as needed.

Now pick up the knife. On the side that is not being sharpened, run a thumb or finger across the flat of knife from the spine to the edge. On the edge, you should feel a burr. When you can feel the burr along the entire length of the edge, that side is done, otherwise it needs more work. Now sharpen the other side until you can feel the burr on the other side. We'll address a complete lack of burr later.

 _  <- Burr
  \
  /\  
 /  \
 |  | Just sharpened side
 |  | 

Once you have done both sides, go up to your next stone and repeat.

As the stones get finer, the size of the burr gets smaller and harder to feel. On a 3000 stone, it gets very fine. If you cannot feel it, wash the blade of any material that you removed. This can sometimes help you feel the burr. I also find that dry hands work better than wet hands when trying to detect the burr.

6. Finishing

When you get to your final stone and have done both sides, you need to remove the burr. Just hold the knife at the same angle as you've been using with the burr side in contact with the stone, and pull the edge of your knife across it to remove the burr.

You can also strop your blade, but it is not necessary.

7. Reflatten your stone

You can do this with a special flattening stone, or a bit of very fine sandpaper. I wet some 600 grit sand paper and put it on my bench (flattest surface in my home). Then sand the stone down. It only needs a few strokes if you do this regularly.

Don't feel a burr trouble shooting

If you have been working at if for a while and cannot feel the burr here are a couple of suggestions.

Wrong angle

Your angle may be too low. Increase the angle slightly and try again. On a coarse stone, you should be able to feel the burr after only a few strokes.

Knife is too blunt

Detecting the burr only works if the knife is close to being sharp. If it is too blunt, you need to remove a lot of material before you are close to a sharp edge again. Don't do this. If you do, you'll end up with an asymmetrical edge.

  _            
 / \                                      /\
/   \  Keep working one side and you get /  \
|   |                                    |   \

Instead, give a few strokes across the entire length of one side. Flip it over and do the other side. Make sure you do a similar amount of work so that the edge is symmetrical. The idea is to try and meet in the middle. Check after working each side and eventually you will get a burr.

  • That is exactly the type of stone I have! Very useful – user2766 Dec 4 '14 at 16:00
  • @Liam, great that I could be of help :) – Viktor Mellgren Dec 5 '14 at 8:04
  • I've cut and pasted a summary of the linked answer as I think it's the most useful. – user2766 Dec 8 '14 at 17:17
10

You are right about using the rough side first and then some polishing with the finer side. Holding an angle is a real tricky part and needs some stability and skill.

To prevent the blade from getting damaged, you can run an ink marker over the cutting bevel. This way you'll have a reference to manage the amount of tilt you need to have. The typical angle should be between 15 to 20 Degrees.

Check if it is okay to lubricate the stone with water or edible oil before you go ahead.
Make slow strokes rather than faster strokes. There are 2 basic reasons behind preferring the lubrication:

  • That gives you more control over the angle.
  • Removes the metal powder left out of when you sharpened a knife last time around, so that the stone remains clear and efficient as the grain-pattern remains clean.
  • Acts as a cooling agent where the friction takes place.

As you proceed to polish it, all the ink should go off. Once the ink is gone, you can take a look at the knife with the blade edge in line with light and tilt the knife around a bit, slowly. If you see any glint on the edge, that part needs some work with the finer side of the stone.

Once done, clean off the stone!

  • 2
    Inking the edge is a good idea! – user2766 Dec 4 '14 at 10:57
7

Ray Mears has produced videos on sharpening knives. In particular, sharpening them in camp and in the field.

The teqhnique is pretty much as @WedaPashi explains it, but it's good to see a video of the correct approach.

6

Honestly it's pretty tricky. The other answers have good info but I thought I'd add a tip:

Once you think you've found the correct angle, you can use your thumb on the back of the blade as a guide to keep it at this angle against the stone. Rest the bottom of your thumb on the stone as you move the knife across it and it will keep the knife at a fairly constant angle.

Run the knife across the stone a few times this way and you should be able to see where the stone is grinding, by which part of the knife is shiny. If it's along the cutting edge and is approximately covering the whole of the existing bevel (and not just one edge of the bevel, which would indicate that you are at too sharp or too shallow of an angle) then you know what angle you're aiming for.

Don't be discouraged if it takes you a few times to get right. It can be better to start with a cheap knife before using your favourite one. Also generally speaking, don't expect to get a razor sharp edge with just a whetstone as you typically need either a really fine diamond stone or a leather strop to finish a blade to that standard.

  • 2
    Nicely put. +1 for "...Don't be discouraged if it takes you a few times to get right. It can be better to start with a cheap knife before using your favourite one" – WedaPashi Dec 5 '14 at 6:13

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