The reason for that is I don’t use oil or water or any other lubricant when I sharpen, I sharpen dry and only use water with soap to clean my stones after use. This even applies to old oil stones I acquire; when the need arises I wash them with soap and water. And there is a very good reason for this, actually a couple of reasons.
A number of years ago back in the mid 1980′s I read an article in either Popular Science or Popular Mechanics Magazine about sharpening on stones. The article included photomicrographs of the surfaces of both plane irons and chisels.
All samples had the same grind from the wheel and were photographed before any work on the stones. Then one set [plane iron and chisel] were sharpened in the traditional manner using oil as a lubricant for the process. The other set [plane iron and chisel] were sharpened using the same stones but with no lubrication on the stone. The photographs comparing the two were remarkable.
The tools sharpened ‘dry’ had nearly perfect edges while the tools sharpened ‘wet’ showed tiny chips in the cutting edge and these were caused by, according to the article metal particles suspended in the oil. These metal pieces were floating in the oil and striking the cutting edge causing the chips.
I immediately started using the ‘dry’ process and haven’t gone back. I use soap and water to clean the stones when they become filled or glazed and the stone is ready for the next sharpening session. Because it takes a while to fill a stone I don’t wash my stones that often.
Another advantage to this method is that there is little or no mess made while touching up an edge of a tool; no need to wash off the oil or dirty water before going back to work. Give it a try and see what you think.