Sharpening knives is shrouded in mystery and confusion. Everyone knows someone who claims to have the perfect answer to the thorny question of how to get a good edge. Most of us simply imitate what we see those that should know how to sharpen a knife, doing it - generally with a steel rod (commonly called a steel) - on TV, in the butchers / fishmongers or in other similar environments. My experience is that in most homes, where it is not necessary to sharpen knives frequently, the person sharpening rarely gets the best possible result. There are lots of reasons for this.

That's why I have written this guide. Sharpening knives at home and enjoying the benefits and pleasures of using sharp blades is not difficult and can be mastered by anyone with a little practice. However let me warn you now that once you are proficient in the 'art' you will forever be getting requests from family and friends to sharpen their knives for them!

So lets begin - First you need to understand a little about knives as well as why & how they blunt, then I can explain how to sharpen.

A little information about knives and knife-edges

The cutting edge of a knife, by definition, has to be very fine. The shallower the angle of the edge the sharper the blade - see Diagram 1. Also, the thinner the blade, the sharper it is or the sharper you can make it - for example, a single sheet of paper can cut you even though there is no 'angled' edge on it merely because of its thinness. Therefore, the thicker the blade, the blunter it is or the harder it can be to sharpen.

Diagram 1

The most common reasons why a knife blunts:

First, the surface you cut on.

The ideal surfaces to cut on are wood or high-density plastic boards (which are very hygienic, dishwasher proof and available at all major supermarkets). If you cut on glass, kitchen tiles, china, marble, metal or any hard surface the knife will blunt EXTREMELY quickly.

This is because with a hard surface there is no 'give' or softness that the blade edge can cut into, so when you 'push' down on the blade the edge simply bends over rather than staying straight and cutting into the surface.

Diagram 2

Second, cutting technique.

If you tend to push down heavily to cut rather than slice with just a little downward pressure your knife will blunt a lot less because you don't put as much pressure on the edge and so it does not bend as much or as fast.

If you chop by lifting the whole blade off the cutting surface and bring the blade down heavily onto the cutting surface to cut through whatever it is you are trying to chop, then the edge hits the cutting surface with hard impact and it will either bend or flatten. The best way to chop is by keeping the tip of the blade on the surface all the time, and simply using the very back part of the knife to perform the cut, that way the impact on the blade edge is less and therefore less damage or wear is caused.

If you need to perform heavy chopping as you may do when preparing large pieces of meat or cutting into bone etc. a cleaver should be used. This should never be extremely sharp as a very fine sharp blade will simply break off (or chip) if it hits anything very hard. As I explained before in order for a blade to be razor sharp, by definition, it has to be very thin or the angle very shallow so that the cutting edge is very thin.

Diagram 3

Third, the material the knife is made from.

The softer the material the quicker the blade will go blunt. Stainless Steel is very soft and so goes blunt very quickly whereas High Speed Steel is very hard so blunts very slowly. Everything else, as far as steel is concerned, falls between Stainless Steel and High Speed Steel.

Adding or filtering certain elements promotes hardness; this produces a better grade of steel for knife making. Carbon and Vanadium are the most commonly used such elements.

Therefore, the higher the percentage of these additives the better the steel for knife making. Furthermore, adding Carbon also causes the steel to become more brittle which makes for easier sharpening. Adding Vanadium, when combined with Molybdenum, helps with the anti corrosion/discolouring properties.

As current fashion and consumer demand requires stainless finishes, and Carbon does oxidise very quickly if left wet, most knife makers who use High Carbon steel add Chromium to make their knives stainless. Unfortunately, in my experience, the addition of Chromium makes the knives harder to re-sharpen.

I have made an approximate guideline chart of the various materials that are generally available below and their relevant capabilities.

Material	Carbon content	Edge retention Capacity	Initial / First sharpening	Frequency of re-sharpening	Ease of sharpening
Stainless Steel	Less than 0.5%	Poor	2/3 Months	After every use	Difficult
Stainless Steel with Molybdenum Vanadium	Less than 0.5%	Adequate	3/4 months	Every week	Difficult
High Carbon Stainless Steel	Less than 0.8%	Good	5/6 months	Every 4/6 weeks	Moderate
High Carbon Steel E.g. AUS 8	Less than 0.8%	Good	5/6 months	Every 2/3 months	Easy
High Carbon Steel E.g. Yasuki Steel	More than 1%	Very good	6/8 months	Every 2/3 months	Very easy
High Speed Steel E.g. HRS 15	More than 1.5%	The best	12/18 months	Every 4/5 months	Moderate
Zirconium Ceramic	Not applicable	Very, very good	12/18 months	Every 6/9 months	Moderate
Titanium	Not applicable	Questionable	Variable*	Every 4/6 months	Very difficult

 

Please note that this chart is made from my personal experience and so the timescales will vary according to your personal style and usage.

Finally, wear & tear.

All good knives will blunt over a period of time simply through regular use. The knife edge which starts off with straight and accurate angles will eventually round out and therefore not be sharp.

The speed with which this happens will again depend on the material used and its hardness see the chart below that also indicates the advantages and disadvantages as well as availability of the various qualities of knives.

* I have experimented with Titanium blades (which by the way can vary in price category from very cheap - £6.99 - to very elite - ~ £150.00) and have found them to be light, not razor sharp but quite sharp and very difficult to re sharpen.

I have illustrated below the various ways a knife generally blunts:

Diagram 4

Availability and advantages & disadvantages of various materials:

Material	Availability	Sharpness	Durability	Ease of resharpening	Advantages	Disadvantages
Stainless Steel	Everywhere	Medium edge	Poor	Hard	Should be cheap to buy Looks clean	Looses edge very quickly Difficult to sharpen.
Molybdenum Vanadium Stainless Steel	Quality stores and specialist cook shops JKC Classic & Classic II	Good	Sufficient for most domestic uses	Hard	Looks good with a reasonable edge	Difficult to resharpen after the factory edge has gone
Traditional High Carbon Steel	Specialist shops only JKC Best Clad Collection	Very good	Very good	Very, very easy	Fantastic edge, edge retention and very easy to resharpen	Discolours as result of oxidisation
High Carbon Stainless Steel	Quality stores and specialist cook shops JKC New Tradition Collection	Very good	Good	Not difficult with practice	Good edge that can be sharpened with practice and remains relatively stainless with a little care	Harder to resharpen than traditional high carbon and more expensive
High Speed Steel	The JKC Artisan is the only range I know of available at present	Unbelievable - the best	Unbelievable - the best	Requires a little practice	The best and long lasting edge I know of and remains stainless	Expensive
Titanium	Specialists shops only	Adequate	Very good	Very hard	Looks - if you like blue blades. Good edge retention	Expensive and hard to resharpen
Ceramic	JKC Ceramic collection is widely available and on this site	Very good	Very good	Needs special sharpener and technique though the JKC ones can be sent back for free re-sharpening for 5 years	Non-metallic won't discolour food like lettuce. Won't influence the flavour of food. No cross contamination of smell or flavour between cuts with just a light clean. Edge retention is good. Free sharpening	Expensive. Can be chipped if misused. Can loose tip I misused. No flexibility so can break if used for any kind of prising.

How to re-sharpen

In order to make the knife sharp you need to get the edge back to a nice even angle on both sides if the blade.

If the edge is simply rolled you can realign it easily with the minimum of effort by simple placing the edge onto a sharpening system harder than the knife and stroking it back into line. This is effectively what the butcher and fishmonger or the guy in the kebab shop is doing when he 'puts' the knife onto 'steel' in between each use. This very frequent 'realigning' is required because they are using relatively inexpensive knives made from soft steel that means that the edge itself, which is very fine, is easily rolled over.

If the knife has a flattened edge then it needs to be gently ground out and realigned. This requires a more aggressive action with more pressure to regrind and realign. I personally do not like to use a 'steel' for this, as with the speed and pressure required it is very difficult to maintain an even and regular angle across the entire length of the blade. You invariably end up with a blade that is sharpened at different angles in different parts of the edge. This 'wave' makes the knife feel like it is struggling through a cut rather than slicing smoothly.

If the edge is worn it needs a proper regrind and this can only effectively be done on an abrasive surface like a whetstone or grinding wheel. This is just like using sandpaper - the rougher the abrasive surface the rougher the finish, and the smoother the surface the smoother the finish. And just like sandpapering the smoother the abrasive the surface the harder you will have to work to get the edge. This is why it is easier to use a rough abrasive first to do most of the grinding work and then simply finish off with a smoother abrasive to achieve a polished edge.

As most knives are blunt from a combination of all of the above reasons the best method of sharpening is to use the stone. Second is some device that makes Method 2 easy and last is the 'steel' that has to be done very frequently and with great care to maintain the angle.

Using a 2 sided stone - JKC Whetstone Kit:

1. Place the Whetstone into cold water so that it is completely submerged and leave until the air bubbles stop (approximately 1 hour). The stone must be thoroughly soaked before use.
2. Soak a small towel in water, wring out the excess liquid and place on a flat waterproof area like the side of the sink. Place the pre - soaked Whetstone vertically, smooth side down on the centre of the mat. The wet mat will prevent the stone from slipping during sharpening and also collect the excess dirty water.
3. Keep a small jug of cold water handy to lubricate the blade edge during sharpening.
4. If you are using one, carefully slide the angle guide with the plastic protector fitted onto the centre of the back of the blade. When the blade (sharp side facing away from you) is placed on the stone the guide will automatically provide a perfect angle to sharpen your knife at.
5. If you are not using an angle guide then place the spine of the knife against your thumb and grip the knife firmly with two fingers of the other hand on the side of the blade to give you control.
6. Run water over the entire length of the blade. Now rub small sections of the blade up and down along the full length of the rough side of the stone until the whole blade length is sharpened. If you are using a guide, keep a part of the guide on the stone all the time to maintain an even angle. If you are doing the sharpening freehand then ensure that you maintain an even angle THROUGHOUT this rubbing process. Keep pouring a little water, as required; to keep the abrasive surface and the sharp edge wet ALL the time. This 'grinding' is the most important part of the sharpening process and should be carried out with accuracy. Continue sharpening for between 2 and 4 minutes and, if you are able, until you hear a change in the sound of the grinding from a coarse to a soft note.

   

   You may chose any angle between 12º and 15º so long as it is constant throughout the sharpening. The shallower the angle the sharper the result. DIAGRAM SHOWS EXAGERRATED ANGLE

   

   It is essential to keep the side of the blade at the same angle to the surface of the stone ON BOTH SIDES of the knife. If it varies you will not get a good edge.

7. The re-honing is now complete and the blade edge needs to be polished to get rid of any excess burr or loose metallic particles.
8. Turn the stone over so that the smooth side is now on top, and repeat step 5 on the smooth surface for between one and two and a half minutes. Once again the angle of grinding should be the same ands held even as during the original sharpening in step 5/6
9. Wash and dry the mat whilst allowing the stone to dry NATURALLY before storing.

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