Knife Sharpening Stones

What are sharpening stones ?

Sharpening stones, commonly referred to as whetstones, are fundamental tools employed to sharpen blades through the process of grinding against an abrasive surface. This grinding process is often referred in general terms as Honing, Grinding and Sharpening. Made from a range of natural and synthetic materials, these stones vary in abrasiveness, grit, and speed. Some synthetic abrasives and even some natural stones offer dual sides—a coarser side for heavier sharpening tasks and a finer side for finishing. These sharpening stones for knives are essential for repairing, sharpening, and maintaining your tools.

What is a sharpening stone used for?

Sharpening stones for knives are tools used to maintain the sharpness of knife edge, razors etc. They serve to restore and refine the cutting edge, removing dullness and imperfections caused through use. By abrasively grinding away material from the blade’s edge, sharpening stones enhance its sharpness and effectiveness. Different grit sizes cater to varying degrees of sharpening needs, ranging from coarse to fine. Regular use of sharpening stones ensures that blades remain sharp, facilitating precise cutting and prolonging the lifespan of tools.

Types of Sharpening Stones?

Whetstones are crafted from various materials, each yielding distinct finishes on the applied surface. The common categories include:

Water Stones:
Water stones are synthetic stones used with water as a lubricant during sharpening and depending on the brand, may or may not require soaking before use. Japanese name brand water stones are among the most diversified and prevalent water stones, although they can originate from anywhere. They are usually made with harder abrasive materials like aluminum oxide, silicone carbide, and ceramic.

Natural Sharpening Stones:
Natural Sharpening stones occur in nature and usually bear the name of their geographic origin which also defines their overall grit level. For example, Belgian Coticules, Arkansas stones, Charnley Forrest, Dragon’s Tongue Welsh Stone, etc. all have a coarse, medium, or fine association to their name. Interestingly, Japanese Naturals (also called JNats) follow the same naming properties describing the origin and features of the stones – but in Japanese. Natural stones are made from varying natural materials ranging from quartz, slate, and garnet, and were formed under heat and pressure with other natural occurring binders like mud, silt, silica, and mica.

Oil Stones:
Oil stones are synthetic or natural stones that are used with oil as a lubricant. Most common oil stones are Arkansas stones and India stones. These are beneficial if there is a very high rust potential to your knife. Traditionally, carbon steel blades used oils stones.

Diamond & CBN Stones:
Diamond & CBN stones are diamond or CBN impregnated plates that can cut through all materials. They can be in raw form or embedded in a resin matrix. Diamond are the hardest material, and CBN is the closest, next hardest abrasive to diamonds. They have become very popular due to the increased use of abrasion resistant steels in knife making. They can be used dry, with water, or oil.

How to Use a Sharpening Stone?

When using a sharpening stone, larger ones, known as ‘bench stones’, are intended for use on a stable surface like a bench, desk, or stone holder while smaller, more portable ones, termed ‘pocket stones’, are often used while holding them in hand. There is a growing market of custom sized stones that fit into specialized stones holders for guided sharpening systems.

For heavier work with a coarser stone, secure in place to prevent sliding, and use even pressure and angle consistency during sharpening.

Keep the surface of the stone lubricated with water or oil, depending on your stone. More lube or a cleaner stone usually makes the stone cut more aggressively, while building a paste or mud on top of the stones, or running them dry makes the resulting edge slightly finer. Only use water or oil as a lubricant, and don’t change to the other once you start using the stone. Certain water stones may require a presoak for about 2-10 minutes, or until the bubbles stop.

Once the sharpening stone is prepared, begin pushing the blade’s edge across the abrasive surface in a criss-cross motion at a 15-20° angle. Maintain even pressure by resting your fingers on top of the blade. Alternate sides and angles to achieve optimal results. The knife sharpening stones are sometime used alone and sometime also used with Guided knife sharpening system.

What are the Shapes of Sharpening Stone ?

Sharpening stones are available in four fundamental shapes:

• Rectangular
• Round
• Square
• Triangular

Rectangular stones are the most prevalent and are well-suited for honing broad, flat edges. Square stones excel in delivering fine finishes, ideal for small implements such as keys. Triangular stones are perfect for intricate work, particularly in small recesses. Round sharpening stones offer a curved surface, making them suitable for sharpening serrated blades, rounded tools like gouges, and refining other fine blades with a curved profile.

What are the Grades of Sharpening Stones ?

Sharpening stones are graded based on their grit size, which denotes the rough particles within the stone. The grades include:

• Coarse: 60 grit to 800 grit
• Medium: 800 grit to 3,000 grit
• Fine: 3,000 grit to 8,000 grit
• Super Fine: 10,000 grit +

Coarse stones are ideal for heavy-duty tasks like reshaping damaged blades, while medium stones are suitable for pure sharpening and maintenance work. Finer stones polish the blade post-sharpening. Some synthetic stones offer dual sides for versatility. Grit size is indicated by printed numbers, with lower numbers representing coarser finishes. However, these numbers are approximations and do not precisely correspond to particle size. The smoothness of the finish depends on various factors like particle shape, exposure, pressure resistance, and overall strength. Common grit sizes range from 120 for reshaping to 30,000 for achieving an extremely smooth, mirror-like finish.

Care of your sharpening stones for knives
One thing almost always overlooked with sharpening stones is the importance of stone maintenance. All stones wear and with the exception of diamond and CBN plates, all stones will dish over time. It is of the utmost importance that your stones should be flattened consistently so that they can perform to their optimum level, especially if you use two or more stones in a sharpening progression. Lapping plates can be made from glass with silicone carbide powders, sand paper, or a diamond plate.