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We're all familiar with bonded abrasives--synthetic stones usually made of aluminum oxide or silicon carbide. Despite the prevalence of natural, diamond, and ceramic stones, bonded abrasives remain the humble workhorses of manual sharpening equipment. The familiar old dual grit rectangular "crystolon" or "India" stones are obviously the most widely known, but there are three relatively unsung heroes that deserve much more attention. At least one you have almost certainly at least heard of, another you might or might not have seen before, and the last you more likely than not haven't seen at all. I present them all below:
The Puck
This is the fellow you probably know well. Most commonly found in a coarse/medium dual grit, though single grit and natural versions exist, the puck stone is a highly portable grinding stone you can hold in the palm of your hand. Usually used in a circular "scrubbing" motion, these stones will rapidly form and shape flat or convex bevels on a variety of tools, and their compact form and short strokes allows them to reach low angles without experiencing clearance issues on edged tools that have any sort of raised lip to them behind the edge. Often referred to as an axe stone due to their common usage in beveling and sharpening the tool, they are also useful for applying bevels and rough edges to machetes, cleavers, shovels, hoes, mattocks, and more, as well as repairing heavy damage on the edges of finer-edged tools before progressing to more refined grits.
The Canoe Stone
Also known as a "lawn & garden" stone or a scythe stone, you may or may not have seen these fellows before. My preferred stone for general sharpening tasks, the broad flats may be used for upwept (conventional) and straight-edged blade forms and to produce flat or convex edges while the curved, tapered edges may be used with a rolling stroke to produce hollow bevels, and is particularly well-suited to forward-curving blades like pruning knives, scythes, sickles, and billhooks as well as recurved blades like kukris. Also found in fine natural stones, though sometimes only the curved edges will be worked smooth. The shape of these stones can be understood as the intersection of two circles, like the center overlap of a Venn diagram. As such, each curved edge is like a small section cut from the edge of a large diameter grinding wheel. The reason for the use of a rolling stroke is to keep the angle constant in spite of the curve, mimicking the rotation of a grinding wheel in action. This also provides good clearance in the case of raised lips on blades in spite of the long stroke of the stone, allowing a lower angle of approach than a flat stone of equal length could otherwise produce or maintain. An extremely versatile stone shape.
The Cigar Stone
Some of you might have seen these before, but I reckon if you have you're the exception to the majority. These stones, also known as American pattern scythe stones, have almost disappeared from the market. The lenticular (lentil or lens shaped) cross section allows it to be used for both upswept and forward-swept blade profiles, and produces flat or convex bevels. The ability to be used on both forward and rearward curving blades without having to modify your hold on the stone or roll the wrist allows the user to rapidly develop proficiency in holding a consistent angle or for the experienced user to be able to sharpen a tool with little attention given to the task beyond getting the angle where they want it. A stone of great convenience.
The Puck
This is the fellow you probably know well. Most commonly found in a coarse/medium dual grit, though single grit and natural versions exist, the puck stone is a highly portable grinding stone you can hold in the palm of your hand. Usually used in a circular "scrubbing" motion, these stones will rapidly form and shape flat or convex bevels on a variety of tools, and their compact form and short strokes allows them to reach low angles without experiencing clearance issues on edged tools that have any sort of raised lip to them behind the edge. Often referred to as an axe stone due to their common usage in beveling and sharpening the tool, they are also useful for applying bevels and rough edges to machetes, cleavers, shovels, hoes, mattocks, and more, as well as repairing heavy damage on the edges of finer-edged tools before progressing to more refined grits.
The Canoe Stone
Also known as a "lawn & garden" stone or a scythe stone, you may or may not have seen these fellows before. My preferred stone for general sharpening tasks, the broad flats may be used for upwept (conventional) and straight-edged blade forms and to produce flat or convex edges while the curved, tapered edges may be used with a rolling stroke to produce hollow bevels, and is particularly well-suited to forward-curving blades like pruning knives, scythes, sickles, and billhooks as well as recurved blades like kukris. Also found in fine natural stones, though sometimes only the curved edges will be worked smooth. The shape of these stones can be understood as the intersection of two circles, like the center overlap of a Venn diagram. As such, each curved edge is like a small section cut from the edge of a large diameter grinding wheel. The reason for the use of a rolling stroke is to keep the angle constant in spite of the curve, mimicking the rotation of a grinding wheel in action. This also provides good clearance in the case of raised lips on blades in spite of the long stroke of the stone, allowing a lower angle of approach than a flat stone of equal length could otherwise produce or maintain. An extremely versatile stone shape.
The Cigar Stone
Some of you might have seen these before, but I reckon if you have you're the exception to the majority. These stones, also known as American pattern scythe stones, have almost disappeared from the market. The lenticular (lentil or lens shaped) cross section allows it to be used for both upswept and forward-swept blade profiles, and produces flat or convex bevels. The ability to be used on both forward and rearward curving blades without having to modify your hold on the stone or roll the wrist allows the user to rapidly develop proficiency in holding a consistent angle or for the experienced user to be able to sharpen a tool with little attention given to the task beyond getting the angle where they want it. A stone of great convenience.
