Sharpening Stone Materials
Sharpening stones can basically be divided into two categories: Natural stones and synthetic stones.
Natural stones are stones of natural origin that are quarried.
Synthetic sharpening stones, including the most common types – ceramic and diamond sharpening stones – are man-made from various materials.
Natural sharpening stones
are cut in a quarry, trimmed to size and ready for use.
In principle, you could sharpen with any stone of natural origin, but the sharpening result is different with every stone and only very few natural stones are fine and yet hard enough to achieve satisfying sharpening results.
Quarry in Honyama, Japan
Examples of natural sharpening stones:
»Honyama« Quarry Stones (No. 711303) Although fine stones from the Honyama site are increasingly difficult to acquire, many experienced tool sharpeners swear by these special natural stones.
»Aka« Japanese Natural Stones (No. 711534) Medium-coarse grit lime sandstone, very open texture, with good honing properties. From the Amakusa region.
Natural sharpening stones usually remove less material, and thus achieve controlled and precise sharpening results. As a consequence, the sharpening process takes longer than with synthetic stones.
Another thing to bear in mind is that every natural sharpening stone is different. Since the grit cannot be determined exactly, manufacturers merely give a rough estimate of, for example, 6000 to 8000 grit.
Ceramic sharpening stones
green silicon carbide
Synthetic, ceramic particles are sintered to form sharpening stones.
With ceramic sharpening stones, the grit can be specified very precisely. The ceramic particles are produced synthetically, which means that a sharpening stone labelled with 8000 grit reliably has 8000 grit
The basic material for ceramic stones is powdered white, brown or grey aluminium oxide or silicon oxide. The synthetic powder is produced in laboratories in the desired grit size. The powder is then mixed with a bonding agent and pressed into shape. The agent usually consists of natural products such as cellulose, wax, clay or magnesium, but you can also use synthetic products such as polyacrylates, polyvinyl alcohol or various synthetic resins for bonding.
Once in the mould, the substance is heated almost to the melting point, sintering but not melting completely, resulting in very hard, ceramic sharpening stones.
The different colours of sharpening stones usually come from dyes added by the manufacturer to make it easier to distinguish between the grits.
Examples of ceramic sharpening stones:
Kunsuto® Sharpening Stones (No. 711248) This stone series was developed in cooperation with an expert in Japanese sharpening stone. The aim was to create a Japanese stone series suitable for both high-alloy tool steels and low-alloy carbon steels.
Shapton® Glass Stones (No. 711615) The sharpening particles of these white aluminium oxide sharpening stones are highly pure and homogeneous. This is noticeable in the transition to finer grits, with the grinding marks of the previous grit being quickly removed. The sharpening stones of this series are 100 % warp-free and do not need to be watered.
Diamond sharpening stones
usually consist of almost warp-free supporting plates to which tiny diamond particles are applied. Since the material hardly wears out when used correctly, a quite thin layer of abrasive particles is sufficient.
Examples of diamond sharpening stones:
DMT® Whetstone™ Sharpening Stones (No. 706285) Diamond-coated sharpening devices remain permanently flat, and are especially suitable for tools with straight blades, as well as for producing flat surfaces (e.g. backs of plane and chisel blades, plane soles, scrapers).
M. Power Tools DC™ Bench Stones (No. 740853) Diamond Cross (DC) sharpening stones offer an excellent price/performance ratio with a high manufacturing quality. Monocrystalline* diamond particles guarantee a long service life and excellent material removal. Uniform grit sizes and a dense diamond distribution for even grinding patterns. The wave-shaped recesses prevent clogging due to grinding debris.
Diamond is the hardest natural material in the world. Therefore, in most cases, diamond sharpening stones do not wear out and remove material very quickly. No water or oil is needed for sharpening, but a little water or WD-40 can make the process a little more comfortable. It is important that hardly any force is used when grinding.
If too much force is applied, the diamond layer is likely to show signs of wear.
The diamonds used for the sharpening stones are not of natural origin. They are produced in labs and are almost identical to real diamonds on the molecular level.
The production of diamond sharpening stones includes a complicated process of electroplating. By means of electricity, the iron plate is coated with a nickel layer that binds the diamond abrasive particles.