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Selecting A Sharpening Stone:

Understanding The Differences In Materials

The three most common types of sharpening stones are water stones, diamond stones, and oil stones. Each of these stones has its own advantages that can help users achieve their sharpening goals. Below we'll get into into the differences between each sharpening stone material.

Water Stones


Water stones have become very popular due to their many performance advantages. Water stones are available in both natural and synthetic materials. However, the vast majority of water stones and man-made so we'll discuss those specifically.

Water stones are often made of Aluminum Oxide abrasive material. This is the same abrasive material found in oil stones like the Norton India Stones. The The difference between a water stone and an oil stone is the binder that holds the abrasives together. Water stones are softer than oil stones. This softer binder promotes faster cutting because the old abrasive material breaks away and is replaced with fresh sharp material.

Fast cutting is a clear an advantage of the water stone. It is also available in a much wider range of grits than most other stones. Water stones are available in grits as coarse as 120 grit and easily found in grits above 8000 (the finest being 30,0000).

The other obvious advantage is the use of water rather than oil to remove the swarf from the stone. Water not only cleans up easier, but it is something that is almost always readily available.

The softness of the water stone does have one downside. As the stone wears, it must be flattened periodically. For this reason, when owning a water stone, a is highly recommended.

Our most popular lines of water stones are the Naniwa Super Stones, Naniwa Professional Stones, Shapton Kuromaku, Shapton GlassStones, , and Sharpening Supplies Water Stones,.

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Diamond Stones

Diamond Sharpening Stones

Diamond stones contain small diamonds bonded to 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 first contains holes in the diamond surface to capture the swarf, this is called an interrupted diamond surface. These stones cut very fast and are very simple to use. Examples of this style are the DMT Duo-Sharp line of diamond stones. The next type is the continuous diamond surface, an example of this style is the DMT Dia-Sharp line of diamond stones. The continuous diamond surface is preferred when you are sharpening tools with points that might get caught in the recesses of the interrupted 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 DMT stones we carry are all mono-crystalline diamonds.

The two greatest advantages of the diamond stone are the very fast sharpening and the flatness that is retained by the diamond stone. In fact, extra-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.

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Oil Stones

Norton Oil Stones Oil stones are the traditional Western stones that many people 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 most traditional 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 Washita is not often used these days because it is very soft. The finer grades are called Soft Arkansas, Hard Arkansas, Hard Black 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 Hard Black Arkansas and Hard Translucent are rarer and are therefore more expensive.

The Aluminum Oxide oil stones are a very popular man-made choice. The most popular are called India Stones, which are made by Norton. 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. When compared with the Arkansas stones, Aluminum Oxide (India Stones) are more coarse. The India Stones are used in conjunction with Arkansas Stones to cover all levels of coarseness.

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. Because they sharpen quickly, it is a common practice to use the Coarse Crystolon and then progress to an India Stone and then to finish up on an Arkansas Stone.

The good overall performance and the lower price are the oil stone’s greatest assets. A set of India or Crystolon stones are the least expensive stones to purchase. The natural Arkansas Stones vary in price from the very economical Soft Arkansas to the more expensive Hard Black and Translucent Arkansas Stones. 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.

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