This comes from the Shapton USA website, How To Use Shapton Stones;
"Always clean your tools and stones before moving up to the next stage in your process. Carrying coarse grit or other materials under your fingernails can cause errant scratches in your surfaces. These stones are very dense and particles will remain on top of the surface if not cleansed carefully.
The most important concept when using the Shapton system is achieving consistancy at a given grit level before moving up to the next finer stone. At the 2000 grit level, your tool should be perfectly shaped. It is ineffective to attempt to reshape your tool at any finer grit level. If you have built a good foundation at the coarse grit level, very little work will be required at the finer grit levels.
Sharpening is an attempt at perfection. The most interesting aspect of sharpening is the reflection of the infinite."