Water Stone vs. Bench Stone

Bench Stones

• Bench stones complement electrical buffing and grinding wheels. They often are used to remove the rough burr or wire edge produced by power grinding. Sandstone traditionally was used to sharpen knives and tools, but modern bench stones can be made of synthetic, natural or diamond grit lubricated with either water or oil. Bench stones come in a variety of shapes to accommodate carving tools. Tapered bench stones with concave and convex surfaces sharpen gouges. Special bench stones sharpen "V" tools and chisels.

Water Stones

• Water stones, traditionally favored by the Japanese, are made of aluminum oxide or green carbide, and use water for lubrication and to wash away swarf. Water stones sharpen and wear away more quickly than oil stones because they contain soft particles that break off during sharpening, thus exposing sharp new particles. These loose particles form a muddy, abrasive slurry that speeds sharpening. Since the top layer of grit on water stones constantly wears away, you periodically have to flatten the top layer with heavy-grit sandpaper or diamond stone. Water stones are available in grit sizes from 100 to 8,000, the largest range of any sharpening stone. Water stones with a 6,000 to 8,000 grit give the finest polish of any sharpening stone. Thoroughly soak the water stone before you use it. Five minutes is sufficient for coarse stones and 10 minutes for medium grit. Fine-grained finishing stones can take up to 20 minutes to soak properly. If you store your stones in water, frequently change the water to prevent the growth of smelly bacteria.

Oil vs. Water

• Lubrication is necessary to prevent fine particles of metal from clogging water stones and oil stones. Silicon carbide oil stones cut faster than water stones and are good for initial, coarse sharpening. Oil stones also last longer than water stones, and you don’t have to flatten them as often. Particles of metal roll and become dull, filling up pores of oil stones, making sharpening less efficient. Use a clean, dry cloth to remove the particles. If oil stone surface becomes clogged, remove the particles with sandpaper or diamond stone. Water is easier to clean than oil. It dries quickly and does not stain the wood.

Synthetic vs Natural

• Long-lasting synthetic stones made of aluminum oxide or silicon carbide usually are lubricated by kerosene or medium-weight oil. Novaculite, commonly called Arkansas stone, is a natural stone formerly abundant in Arkansas but in decline as of 2011. Arkansas stone, lubricated by oil, is commonly available in the coarse, fast-cutting Washita grit and soft, hard, black hard, and translucent grits.

Diamond Stones

• Bench stones made of particles of artificial diamonds commonly are bonded to a flat metal plate. Since their rough 220- to 1,200-grit aggressively cuts, diamond stones produce grooves you need to smooth out with a black hard Arkansas or other fine stone. Manufacturers market flexible adhesive diamond strips of 1,800 grit, which is fine enough for finish sharpening.