With its "PROFESSIONAL STONE" brands Naniwa offers a high-tech line of sharpening stones. The Professional Stones are markedly harder than the Sharpening Stones from the same manufacturer. Naniwa designed these stones for professional woodworkers and carvers, who put the highest daily demands on their tools. Overall, these stones are best for those who don't have a lot of time to spend and need to quickly and cleanly sharpen their tools.
Professional Stones stones are harder than the Naniwa Sharpening Stones and so take much longer to develop a hollow in use. These stones also cut faster, especially in the rougher stones -- 3000 grit and larger. The 400-grit Professional Stone, for instance, works faster than the 220-grit Sharpening Stone, and is only marginally slower than the Shapton 120-grit. Normally the Professional Stones only need to have their surfaces moistened a bit with water.
A flat stone is vital to a good sharpening job and flattening stones takes time. Have a look at the flattening blocks and supplies we offer.
IMPORTANT NOTE on storage and lubrication: Professional Stones sharpening stones are bound with magnesium and so have more cutting particles per unit of surface than resin-bound stones. But magnesium-bound stones are much more sensitive to prolonged exposure to water as other types of stones. So Professional Stones stones should NOT be left to soak in water for prolonged periods and must be stored dry. If this advice is not followed the stones can develop hairline cracks or the binding material can be leached out of the stone. It is more than enough to pour a little water on the surface or briefly dip the stones in water, they do not need to be soaked. If you are not sure that you can keep this always in mind, perhaps because you have a number of different kinds of sharpening stones, it may be better to opt for the more tolerant Sharpening Stones.