For chisel sharpening is used as a cooling agent and lubricant.
Most manufacturers clearly state what their stone requires, although a universal remedy which is usually recommended is oil. However, stones that we start with oil should not be used with water and vice versa.
Dry sharpening, on the other hand, is permitted on very few stones, including diamonds.
Ideally suited for sharpening on eg Arkansas and other stones.
It is mineral oil, should be stored in a dark cool place.