The Belgian wetstone is mined from a geological layer which is 480 million years old. This layer is a clay deposit containing fine volcanic ash transformed into stone. Afterwards, during a regional metamorphism, reorganisation of the minerals took place. Some minerals disappeared; others were created like the spessartit garnets which are specific for our wetstones.

Earth movements have a different impact on the yellow and blue veins because both consist of a different composition. If you have a look at the picture of the quarry, you'll see immediately that the yellow veins are more pleated and fractured than the blue schist. Therefore, the blue stones are available in larger sizes than the yellow ones.

This is because of the garnets. As soon as you start sharpening, the garnets leave the stone. Blended with water they form a very abrasive paste. The garnets have a round to oval shape with a dodecahedral structure. They can be compared with a football which consists of a lot of small leather planes, stitched together to form a round object. If the diameter of the garnets is for example 15 microns, only 2 to 3 microns of the obtuse angles of the garnets penetrate into the object while sharpening. In this way, the yellow stone sharpens fast and delicately at the same time.

The yellow stone is most suitable for rapid sharpening and till 8 000 grit. The blue stone is sufficient to sharpen standard knives as carving knives, chisels, scissors,… .

At the current production rate, the stock of our quarry at the "Thier del Preu" site at Sart Lierneux Belgium is sufficient for minimum 100 years of exploitation.

We recommend using water because the Coticule is a non porous stone. Oil must only be used with porous stones to prevent iron particles to migrate into the pores.

The production passes several stadiums. At the quarry, the exploitation of the blue and yellow schist occurs selectively. Then, the rock is transported to the workshop where it gets its final dimensions. Finally, the stones are polished. Every year, 15 000 tons of rock are exploited to produce 10 tons of whetstones. This is only 0.66 % of the total rock!! The largest part of the rock is waste material and is used for other applications.

Yes, you can. If you already have the habit to use oil, you can go on with this. Nevertheless, water is sufficient.

Put a piece of abrasive paper on a flat surface. Add some water and rub the stone over the paper. It’s advised using abrasive paper with sand grains of +/- 80 to 100 micron.

No, see question n° 6. Coticule is a non porous stone so it can’t get clogged.

At least 10 to 20 years! In case of intensive use, its life span will decrease.