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Sharpening Your Knife

We believe one of the most important things a knife owner can do is learn how to sharpen their blade. There's no pont having a great knife is its blunt.

Blunt knives are harder to use and more likely to cause injury to the user. 

www.AussieKnives.com carries a range of sharpeners.  To view the range click here.

1. What sharpener or stone should I use?

There's a big choice out there from stones, diamond sharpeners, steels and guides.  Ultimately your favourite method of sharpening will based upon your personal preference and how you wish to use the knife.

Although there is no substitute for a good teacher in person and a lot of years sharpening on assorted stones we do recommend that beginners at least have a quick look at video sharing sites such as YouTube which yield a wealth of sharpening videos.  You'll see that a lot of these sharpening "gurus" have dofferent methods. We suggest that you look at many of them and take the good ideas from each and discard the useless showmanship.

The below information is a general guide only. 

A. Oil Stones

Oil stones are the traditional Western stones that a lot of us grew up using. These stones are made from one of three materials (Novaculite, Aluminum Oxide, or Silicon Carbide) and use oil for swarf (metal filing) removal.

The first oil stones are natural stones made from Novaculite. These natural stones are quarried in Arkansas and processed to make what we call Arkansas Stones. These stones are separated into different grades related to the density and the finish a stone produces on a blade. The coarsest of them are called Washita. The finer grades are called Soft Arkansas, Hard Arkansas, and Hard Translucent Arkansas. These natural oil stones can produce a polished edge, but tend to cut more slowly than man-made stones.

The next fastest cutting oil stone is called the India stone. The India stone is made of Aluminum Oxide. These stones can cut fast, and can also produce a fine edge on tools and knives. The grading system for these stones is generally labeled fine, medium, and coarse. These stones are often brown or orange in color.

The fastest cutting oil stones are made of Silicon Carbide. The silicon carbide stones made by Norton are called Crystolon stones. These stones are also labeled fine, medium, and coarse. They are usually gray in color. While these stones will not produce an edge as fine as the India or natural stones, the fast cutting makes them ideal for initial coarse sharpening.

The good overall performance and the modest price are the oil stone’s greatest assets. A set of India or Crystolon stones are the least expensive stones to purchase. These stones are also relatively hard, so the stones rarely require flattening.

The main disadvantage of the oil stone is its slower cutting rate. Of the three main stone types, the oil stone is the slowest. The fact that oil is used to remove the swarf is also messier to clean up than water.

B. Water Stones

Water stones are relatively new to the Western world, but have gathered a large following due to their many advantages. Like the oil stones, the water stones are available in both natural and synthetic materials. However, due to availability, only synthetic stones will be discussed.

Synthetic water stones are generally made of Aluminum Oxide. This is the same abrasive material used in the India stones. However, the difference between the two is the binder that holds the abrasives in the water stone together. Water stones are softer than India stones, which promotes faster cutting because the old abrasive material breaks away and is replaced with fresh sharp material.

Fast cutting is clearly an advantage of the water stone. The other obvious advantage is the use of water rather than oil to remove the swarf from the stone. However, the water stone is not perfect. The softness that promotes fast cutting also wears the stone down more quickly. This tends to wear the stone unevenly, which requires flattening to bring the stone back into shape.

C. Diamond Stones (Plates)

Diamond stones contain small diamonds attached to the face of a metal plate. These small industrial diamonds are much harder than any of the other sharpening stones. However, not all diamond stones perform the same function, nor are they always created equal.

There are two main types of diamond stone styles. The more common style contains holes in the diamond surface to capture the swarf. These stones cut very fast and are very simple to use. The next type is the continuous diamond surface. These stones are preferred when you are sharpening tools with points that might get caught in the recesses of the non-continuous diamond surface. Both types of diamond stones are available in mono-crystalline and poly-crystalline diamonds. The mono-crystalline diamonds are more desirable as they will last longer.

The two greatest advantages of the diamond stone are the very fast cutting that the diamonds provide and the flatness that is retained by the diamond stone. In fact, coarse diamond stones are often used to flatten oil or water stones. The main disadvantage of the diamond stone is its initial cost. While these stones are the most expensive, they will also last a long time, so the long-term cost can be comparable to other stones.

There are good reasons why there are different types of sharpening stones available. There is not one type of stone that is best for everyone. Selecting the right one starts by finding the stone with the best combination of advantages for your particular sharpening needs.

2. The Sharpening Process.

A coarser stone is used when more metal needs to be removed, such as in a nicked or a very dull blade. These coarse stones cut much faster than a medium or fine stone. I have seen beginners try to skip the coarse stone thinking that they can just work on the finer stone longer to save time. Unfortunately, this technique leads to frustration. A coarse stone is an absolute necessity to have on hand because it saves time and sets the foundation for sharpening your edge.

The medium stones are used after the coarse stone and before the fine stone. While skipping this step is tempting, it will cost you a lot of time and wear on your fine stone. The coarse stone leaves a scratched edge. Trying to smooth out the coarse edge with a stone that is too fine will waste time and wear out the finer stone. The medium stone will make the transition from the coarse stone to the fine stone quick transition.

The finest stones are used last to produce the sharpest edge. There are many different levels of fine stones. Any of the stones we carry that are marked fine will produce a good edge for most jobs. However, if you really appreciate an extremely fine edge, look for stones labeled extra fine which will produce an edge as sharp as or sharper than a razor’s edge.

How Sharp is Sharp?

Sounds like a silly question - but once you get into sharpening your blade you'll see there's a differerence between levels of sharp.  What level you need to get your knife to depends on what purpose you want to use your knife... and of course whether the steel you have is good enough to hold an edge of that level.

There are countless ways of testing knives and tools for sharpness. We believe the easiest way to test sharpness is to use the tool or knife for its intended purpose. If it does not cut fast and cleanly and perform its job then it needs sharpening. On a kitchen knife, the knife should be able to cut vegetables with almost no downward pressure. On a fillet or skinning knife, it should be able to cut very quickly without having to saw through the meat.  On a hunting knife it should be able to quickly finish any job with a minimum of fuss.

However - it's no good taking a blunt knife out into the field only to find out it's not sharp enough (although eventually you will know by a quick test if it's ready to go).

So if you want to get down to fine-tuned levels of sharpness there are a few more tests you can use. My personal favorite is to take a piece of paper and hold it vertically. If you try to cut it with a dull knife, the paper will crumple beneath the knife. A sharp knife will cut it cleanly when use a slicing motion to cut through the paper. A razor sharp knife can cut the paper cleanly by just pressing down on the edge of paper without any slicing at all.

Another test is to shave the hair on your arms. While we recommend caution using this method, it can be very useful. A dull or even moderately sharp knife will just fold over your arm hairs without cutting. A well sharpened knife will cut almost all of the hairs in one pass. A very sharp knife will cut all the hairs in its path. This level of sharpness can only be attained using the finest abrasive materials.

Our preferred and quickest test - that you'll be able to use once you've sharpened blades for a while and done the other tests is to simply run your thumb accross the cutting edge.  A sharp blade will have a nice raspy feel and a blunt one will feel dull. NOTE WE SAID ACROSS AND NOT ALONG! Running your finger along a sharp (or relatively dull) blade is silly.  Please also note that the raspy feel should be on the cutting edge and not the side of the edge.  If you get a raspy feeling from the edge - you have a burr that should be taken off by further sharpening.

What's the best angle to sharpen my blade? 

Seems obvious when we say it but the major factor affecting edge sharpness is the angle the blade is sharpened. The lower the angle = the sharper the blade.

Please also note low angle = weaker edge. Very low angle blades include razors or fillet knives where as general purpose outdoor knives and axes will have a higher angle.

As a quick reference we've set out some general angles below.  This is just a general  reference  - once you know how your knife responds to sharpening and know what sort of angle and sharpness you need to get the edge to you can sharpen your blade to the angle you prefer.

Blade Type Recommended Angle
  • Cleaver
  • Machete
  • 30 - 35 Degrees
  • Hunting Knives
  • Pocket Knives
  • Survival Knives
  • Sport Knives
  • 25 - 30 Degrees
  • Chef's Knives
  • Kitchen Knives
  • Smaller Knives
  • Boning Knives
  • Carving Knives
  • 18 - 25 Degrees
  • Fillet Knives
  • Paring Knives
  • Razors
  • 12 - 18 Degrees

    You might also be wondering how you get to a precise angle on your blade.  Well if you're just starting you'll probably find a sharpenign guide or kit from Lansky and other manufacturers very helpful.  Rest assured that once you've being sharpening for a while you'll get a very good "feel" for what sort of edge you are creating.

     

    How do you know if you're done with a stone?
    There are a lot of different stones out there in varying grits and levels of coarseness.  Even different types of stones in the same grit will perform more or less agressively on a blade than others.  Choosing your preferred type of stone and deciding on a favourite will come over time.  For example a lot of people swear by waterstones while others don't like the speed at which they wear.  Ultimately it's as personal a decision as what type of knife you prefer.

    When sharpening you will move from a coarse stone to a finer one and so on until you have the desired edge.  It is important to know when to change stones and move to a finer one.  

    On coarse stones it's very easy. When you sharpen one side you'll notice a burr forming on the opposite side of the edge. This burr is hard to see but is easy to feel. Very carefully feel for the burr by gently running your hand from the spine to the edge. (Do not run your finger along the knife edge from heel to tip, that's only asking for trouble!) A burr if formed when your stone removes material directly at the edge. The burr will move from one side of your knife to another as you alternate sharpening sides.

    Make sure you have felt the burr jump between both sides before you move on to the next finer stone. That will ensure that you have sharpened both sides effectively. The finer grits are done the same way but the burr is much smaller. On the finest grits you may not be able to notice the burr at all. Testing the knife sharpness will tell you when you're done

    3. Using a Guide.

    One more thing to consider before you proceed is if you would like to sharpen your knife freehand or use a guide. Your skill and experience in sharpening will help you decide on the method that's best for you. If you are experienced and comfortable with freehand sharpening, a knife guide may be unnecessary. On the other hand, a knife sharpening guide is an inexpensive and easy way to keep the bevel angle consistent. If you have tried to sharpen before but never achieved the proper edge, we recommend using the sharpening guide.

    4. A Step by Step Guide.

    Now you know about the correct materials to use its time to start the actual sharpening process.

    Step 1: Select the proper coarseness for your bench stone.
    Selecting the proper coarseness for your bench stone is an important first step in sharpening your knife. Not every knife needs to start at the coarsest stone you have, on the other hand a very dull knife can not be sharpened on only your finest stone. Starting with the proper coarseness will ensure that you achieve the edge you need quickly. If your knife is very dull or has a nicked blade, start with your coarsest stone. The coarse stone removes material quickly so a poor edge can be refined quickly. However, the coarse stone must be followed up with your finer stone to refine the edge. If your knife is only slightly dull and just needs a quick touch up, starting at a medium or fine stone can save you time. Starting on a fine stone requires fewer steps but must only be used on an edge requiring little work.

    Step 2: Select the right bevel angle.
    Selecting the right sharpening angle is the next step in sharpening. Regardless of the method of sharpening, a bevel angle should be selected. This angle doesn't need to be exact but following some general guidelines is a good idea. Most knife manufacturers recommend a roughly 20 degree angle. Depending on the use of your knife, you can move up or down from that angle. A fillet knife is never used on anything hard so an angle a few degrees less will produce a sharper edge. On the other hand, a survival knife with various uses can benefit from a more durable edge a few degrees larger.

    Step 3: Apply water or oil to stone.
    Some stones need water, while other stones need oil for floating the swarf (small metal filings created when sharpening) away. Simply apply a few drops of either oil or water directly to the stone. (We recommend using an inexpensive spray bottle for applying the water.) The lubricant you need is determined by the type of stone you are using. Water stones and diamond stones require water. Oil stones such as India, Crystolon and Arkansas stones use oil for a lubricant.

    Step 4: Sharpening the knife.
    Starting with the coarsest stone needed for your knife, you will progress through each finer stone until you have reached the desired level of sharpness.

    Rest your knife on the stone at your chosen bevel angle. An easy method for determining the angle by eye is to visualize a 45 degree angle and then take half that amount. That will give you a ballpark estimate of the angle and then you can adjust accordingly up or down. With a slicing action bring the length of the knife across the stone with a motion that starts with the heel of the knife on the stone and ends with the point of the knife. The motion should resemble a sweeping arc pattern across your stone. Be very careful to maintain the angle of the knife on the stone. Longer curved knives provide additional challenges but as long as you can maintain the angle you will be sharpening very effectively. Repeat this process on the other side of the knife and continue repeating until you have sharpened your knife though all your stone grits.