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How To Sharpen A Knife & Keep It Sharp

So, you have had a good day, and now it is time to fillet your catch. For many fishermen this is the hard part of the whole fishing experience.

Often the crew will draw straws to see who will do the filleting, the loser ending up hacking at the flesh. I sometimes wonder if the task of preparing the catch to eat is the prime reason that drives many anglers into the catch and release camp.

Preparing fish for the table should not be a bore and a chore. In fact with very little effort, filleting fish can be a very satisfying part of the fishing experience.

Using a sharp knife is the key to making fish preparation easier, and more satisfying.

Attempting to fillet fish with a blunt knife is difficult, and dangerous. Trying to cut through bone, skin, and flesh with a blunt knife forces the filleter to 'push' the knife rather than 'slice' with the knife.

This makes the whole job more difficult that it should be, and it can lead to accidents.

It is confession time.

For too many years, I could do nothing to put a sharp edge on a knife. I bought all sorts of devices and gizmos, each with cast-iron guarantees that my knives would be keen enough to shave with, but these all failed me. A truly sharp knife eluded me.

Finally I went down to our local butcher, and in ten minutes, he showed me how to put a proper edge on a knife.

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There are two stages to gaining and maintaining good edge on a blade. These are sharpening and honing.

Sharpening removes metal, leaving a fine, feathered edge.

 This 'feather' on the edge soon bends over with use. Honing straightens the feather. If you leave the feather bent over, very soon it breaks off and you are left with a very blunt knife.

To sharpen a knife you need a good stone. An oil or water lubricated stone will do the job. Diamond impregnated stones do a superb job, but they are expensive. Make sure the stone is at least 8 to 10 cm wide, and 18 to 20 cm long.

If you are using a water-wetted stone, immerse the stone completely in water, for at least 10 minutes, before using on a knife. An oilstone is best wetted with a mixture of oil and kerosene. Diamond stones are either used dry or wet, depending on the stone.

It is important that you read the instructions that come with your stone. Using the wrong lubrication can quickly ruin a stone.

All stones are used in basically the same two ways.

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One is the 'slice the cheese' method.
Hold the knife at a 20-degree angle to the stone. Draw the blade across and down the stone, just as if you were trying to slice off a thin slice from a block of cheese.

Take two or three 'slices' on each side of the blade. Once the knife starts to get sharp, take one or two slices on each side, then one slice on each side. 

The second method is the circular method.
Hold the blade at the same 20-degree angle, and using a circular movement, wipe the blade around the stone. Three circles on each side of the blade, reducing to two circles and then one circle as the blade sharpens.

Some stones are actually two stones joined together, one side coarser than the other. Use the coarse side to begin, and the fine side to finish.

Always wipe the stone down with a rough cloth when you have finished to remove the build-up of steel dust, otherwise the pores of the stone will fill up with steel dust and reduce sharpening efficacy.

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Sometimes, no matter how hard you work you just cannot achieve a decent edge on the knife.

This was my problem. I slaved away at the stone, but a good edge eluded me. It was the butcher who pointed out that my problem was round shoulders. Well, not exactly my problem but the knife's problem.

Shoulder removal

The 'shoulder' may need some explanation.

Even the most skilled cannot maintain a precise blade angle when sharpening a knife. Eventually this will produce a round shoulder above the knife-edge, preventing achieving a straight edge.

This rounded shoulder must be removed at regular intervals to allow the sharpener or hone to work over the full area of the shoulder and edge. 

There are a number of devices on the market that get rid of round shoulders. They feature two tungsten or ceramic pads set at the perfect angle to remove the 'shoulder' off a knife. However they can lead to nicks along the knife edge. Much better to take the knife to a professional.

Once the shoulders have been removed, it is a much easier job to sharpen a knife.

Once the knife is sharp, give it a stroke or two with a good steel. This hones the knife - that is, straightens the feathered edge.

The steel is your best ally in keeping the knife sharp, but it must be remembered that a steel does not sharpen, it merely realigns the feathered edge.

I usually give the knife a pass or two over the steel, after filleting each fish. This constant tickling up of the edge maintains its sharpness. Once the steel is no longer producing a good sharp edge, it is back to the stone.

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The way you use a knife can determine
how long it stays sharp.

 A filleting knife should be used to slice through flesh, not to push through flesh.

To demonstrate this difference in the tackle shop I owned in Auckland, New Zealand, we folded a piece of paper in half, and put the knife-edge in the fold. Then holding the outer edges of the paper, we pushed the knife against the fold. It was well nigh impossible to push the knife through the paper.

But change the angle of the knife, and slice across the fold, and the knife cut through like, well, a knife through paper.

The steel used in your knife is key to how sharp it can be, and how long it will keep its edge.

 As a wild generalisation, stainless steel is softer than raw steel, and it is therefore easier to obtain a sharp edge. But stainless will loose its edge more quickly.

But there is stainless and stainless. As always, good quality stainless will be superior to poor quality stainless, and more expensive.

My knives are non-stainless and were expensive when I bought them more than 20 years ago. Once I learned to sharpen and hone them properly, they became a joy to use.

Caring for your sharp knife is important.

My filleting knives are just that, filleting knives. They are used for nothing else. They say the Lord helps those that help themselves, but Lord help those that help themselves to my filleting knives.

There is no easier way to blunt a filleting knife than to use it for cutting frozen bait, mono, etc.

After filleting, my knives are thoroughly washed, more thoroughly dried, given a light rub down with vegetable oil, and put to bed.

If you have a full tang knife, that is a knife whose steel runs right through the handle, and the handle is made of wood, bone, or antler, do not immerse the handle in water. These natural handles will swell and eventually split, or separate from the tang.

My knives are kept in a soft pouch, not leather, together with my stone and steel.

Just one other quick point about preparing fish - especially important in the hotter weather of summer - never prepare fish on the same surfaces used for preparing meat or chicken.

Use a separate cutting board. You can get very sick indeed from the beasties that can lurk in fish, when combined with the nasties that can lurk in meat and chicken.

Preparing fish for the table should not be a task you would rather not be doing. A good knife, properly sharpened and maintained will make the job a great deal more satisfying.

Footnote: For a very detailed, really, really detailed, and comprehensive look at knife sharpening and maintenance, this site covers it all.

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Article written by Tony Bishop


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