Set of grinding stone BORIDE Ruby 5
Set of grinding stone BORIDE Ruby 5 Set of grinding stone BORIDE Ruby 5

Set of grinding stone BORIDE Ruby 5

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Standard Grit Kit - a set of 5 grinding stones. Medium hard structure. Aluminum oxide abrasive. Also suitable for grinding tool steels. Designed for manual use or in the TSPROF system. Can be used without lubrication or with oil. Size 152x25x6mm. Grit according to FEPA-F. Range F60-220.

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Product detail

We buy Japanese knives mainly because of their uncompromising sharpness. However, it should be noted that each knife slowly dulls with use. It is his natural quality. However, it is up to us to restore it to its original state.

It should be noted at the outset that Japanese kitchen knives generally have harder blades and finer edges than their European competitors. Therefore, grinding them also requires a specific approach. Japanese kitchen knives are sharpened mainly on grinding stones /whetstones/. They are often also called Japanese stones or water stones. In various offers, we encounter diametric differences in the prices of grinding stones, which can of course lead to confusion. So let's talk about them.

Whetstones are primarily divided into natural and artificial. Natural stones were mined in quarries, of which

were the most popular around Kyoto. Today, with few exceptions, they are all closed. However, traders have limited stocks of the base material from which they format the grinding stones. The stones bear the designation of quarry, mountain range, type and finally the degree of hardness. The price of natural stones is significantly higher than artificial ones. Well, as we know, price is a reflection of the ratio of offer and demand. Therefore, with closed quarries, the excess demand is understandable. This means that natural stone does not always have to be of better quality than artificial stone.

Artificial or synthetic stones are an attempt to replace and improve natural stones. Abrasive elements of specific shapes, materials, sizes and quantities are incorporated into the basic material forming the shape of the stone itself. It can be clayey or ceramic. Ceramic is more durable, lasts longer and is designed primarily for grinding very hard steels. Sometimes substances e.g. magnesium, which further improve the stability of the distribution of abrasive segments in the body of the stone are added. There are several manufacturers in Japan, some of which focus on cheaper stones, others on better and more expensive ones. They use their trademarks and it is difficult for the average user to associate a brand with the manufacturer himself. To make the orientation even more unexplored, many manufacturers produce so-called OEM products, i.e. stones for knife manufacturers. These stones bear the logos of cutlery companies and finding their origin is not easy. However, the rule here is that the renowned knife manufacturer offers quality stones that can sharpen its hard blades. In addition, they bear his name and therefore such a purchase is risk-free. In our market we also meet very cheap stones from Chinese manufacturers e.g. TAIDEA. However, try sharpening the VG-10 steel blade with them, not to mention aogami.

With artificial stones, the price says the most about it. It reflects the material of the abrasive elements, their number / grain size /, the quality of the supporting material, the size of the stone and the accessories / pad, toishi /. For example, the dimensions of the stone determine how comfortable and especially how long you will be able to use the stone.

The stones are lubricated before use. Aggressive stones for grinding garden tools are rubbed with oil, but the stones for kitchen knives are mostly lubricated with water. Some require perfect saturation by immersion in water for 10-15 minutes, others just soak briefly and you can start working.

The edges of the Japanese blades are fine and close at an angle of about 15 degrees. The more robust blade is 20 degrees, but beyond this value, the limit for Japanese knives ends and the field of European knives begins. When grinding, it is important to keep the chosen angle, as well as the grinding paste formed on the stone.

If your kitchen knife has a very neglected blade, or even a hint of chipping, a stone with a coarse grain size of 220 to 400 will help you. You can also use such a stone when formatting a different edge angle. The usual basic sharpening uses grain sizes of 800 to 1500. If your goal is a "razor blade" sharp knife, it is advisable to continue grinding on higher granulations 2000, 3000, 4000, 5000 or 6000. Stones with a granulation of 8000 and higher are suitable for polishing the blade, honing.

All the stones in our shop are original grinding stones and come exclusively from Japanese manufacturers. In addition, we also offer additional sharpening methods using grinding rods, ceramic grinders, or the TSPROF professional system. However, if you decide to leave the sharpening of your knives to professionals, all you have to do is bring them to our store.

Video on sharpening Japanese knives provided by Chroma

©2010-2021 Copyright Roman Ulík, Nippon Knives,,all rights reserved.

Photographs and texts are protected by copyright and their use is not possible without the author's consent.

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