How to use a Coticule Whetstone

Coticule Whetstone Knife Sharpener

The Coticule Whetstone is the perfect knife sharpener and straight razor hone. It can be used in a variety of ways. If you have a blunt knife or razor you can rub the small whetstone (slurry stone) against the larger whetstone to create a coarse milky slurry. This coarse slurry will make the stone behave like a rough grade knife sharpener, it will cut steel very fast. Keep working your blunt knife or razor on the slurry until you have reached a ‘sharp’ edge that you are happy with. A little pressure to keep a positive contact with the knife sharpener is all that is required. A watery milky slurry will generally sharpen a straight razor or knife sharp enough to shave arm hair.

Belgian Coticule Wetstone

Once you have maxed out the sharpness of your knife on the milky slurry you can rinse your stone and sharpen on plain water. Use the same sharpening technique you used with the milky slurry. Continue sharpening and checking the edge with your thumb until you are happy with the results. A final finish with a couple of strokes with only the weight of the knife can squeeze the last bit of sharpness out of this knife sharpener. If you are sharpening a very hard knife with 60+ rockwell you may find it beneficial to sharpen on a medium grade slurry before moving to plain water. This would be approximately half the dilution of the initial milky slurry.

With a straight razor you will need to slowly dilute the slurry as you are sharpening. Finishing with plain water. Sharpening a straight razor is more involved that sharpening a knife. This will be covered in more detail in a future blog post.

Straight Razor Maintenance With A Coticule Whetstone

If you have a razor or knife that is sharp and needs a little refresh to bring the edge back to perfection, you can use the Coticule Whetstone with plain water. Cover the top of the stone with plain water and work your knife or razor back and forth along the stone. If you find that plain water is not sharpening fast enough, rub the small slurry stone across the larger stone a couple of times and sharpen on this light coloured misty slurry. A Belgian Coticule Size 1 Bout can also be used with plain water as a knife sharpener, for this refreshing process on knives.

Belgian Coticule Size 1 Bout

You don’t need to rinse the stone and make a new slurry when it becomes grey with swarf. The sharpening particles are still present and the stone will continue to sharpen perfectly. If the slurry starts to dry out, add a drop or two of water. You want the slurry to be watery and not a thick paste. If you knock all the slurry off the top of the stone you can apply some more water and make the slurry again. Try and stop the movement of your knife or razor before the edge of the stone to stop the slurry from being pushed off.

By varying the amount of water in the slurry, you can vary the level of refinement provided by the stone, e.g., from a course knife sharpener through to a very fine knife sharpener, which will provide a true razor sharp edge. The very fine finish provided by these whetstones when used with plain water rivals any man made product. This eliminates the need to have multiple grades of synthetic stones; it is essentially an all-in-one sharpening stone system.

If your whetstone becomes dished or concave over time, you can easily flatten it again. Find yourself a true flat surface (a granite bench top or similar flat surface) lay a piece or approximately 600 grit sand paper on top. Cover with a lot of water and rub the Coticule against the sandpaper. After a few rubs the stone will be perfectly flat again and you will have an ‘as new’ knife sharpener. Work your slurry stone across the surface of the flattened stone to remove the sand paper finish left on its surface.

Belgian Coticule Sharpening Set

The Coticule is a natural whetstone with a long and rich history. The mining and production of this whetstone in the Belgian Ardennes dates back to the 17th century. It is a sediment rock formed from grey-yellowish volcanic ash and clay which contains hard garnet crystals. These thin sediment layers form over 480 million years, sandwiched between slate stone.

The garnet crystals are created by a rearrangement of minerals under the influence of extreme pressures. The Coticule only occurs in thin vertical seams.The extraction of this stone needs to be done carefully and mostly without using machinery. The extraction of this stone is a very slow labour-intensive process, that can only occur a few months per year due to the influence of weather conditions. The production is 100% traditional and makes every stone a unique item.

Coticule whetstone consists of 30 to 42% garnet crystals bonded together with mica. These garnets give Coticule whetstone its exceptional sharpening properties and make it the worlds best natural knife sharpener. The garnets are a dodecahedron shape which has twelve surfaces with obtuse angles. The garnets have a diameter of 5 to 15 microns and penetrate 1 to 3 microns deep into metal.

garnet crystals

This perfect geometric shape for sharpening (obtuse angles polish the metal) and the large numbers of these garnets ensure that the blade is sharpened both very quickly and extremely finely. The smooth shape of the garnets means that they sharpen the metal without leaving behind tiny burrs. This results in a fine finish without scratches on the blade. This makes a knife sharpened with a Coticule knife sharpener very easy to use.

A few examples:

1. A razor sharpened with a Coticule does not damage the skin during shaving. The garnets do not leave any tiny burrs on the blade, which is unique characteristic of the Coticule. This means that there is very little chance of skin irritation. The Coticule gives a razor sharp blade and unrivalled comfort during shaving and the skin is left feeling very soft.

2. Kitchen knives, fishing/hunting and pocket-knives keep their sharp blade for a long time. The speed at which the coticule does its work means they can be made razor sharp again with only a few strokes on this knife sharpener.

3. The blade of any kind of woodworking  tool such as chisels, gouges and axes is polished so finely that wood fibres are cut through quickly and cleanly, resulting in a perfectly smooth finish. There are no nicks in the surface. These stones are sought after by carpenters and sculptors.

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