Either water with a drop of liquid soap or oil. Oil will give better results but makes a bit more of a mess.
No pressure, or just the merest hint of. It can be a slow stone so you might need more strokes.
Better results as in sharper or smoother or both? Were they traditionally used as water or oil hones? I've seen some discussion which seems to suggest that traditionally woodworkers used oil but SR honers used water.
Both smoother and sharper. These are supposed to be oilstones. Oil however can be a bit messy s you can use water. If so, use a drip of liquid soap to break surfacetension, otherwise your water will stay on the stone as drops instead of as film. Results with water are good, but I've found results with oil to be better.
Find that water is the best. Easiest to use and doesn't gum up the stone. Just soak the sone in water for ~30mins and it should retain the surface water that you'll need for honing.
!!! Remember!!!! Your new stone won't be flat!! It has to be lapped before you use it. Find that by 1st making a X across the face that you're going to use with a pencil, then lapping until the X is gone will give you an adequately flat surface. Good luck.
Charnley Forest hones don't need to be soaked and won' t gum up. They're way to dense. You kan soak you CF for all you want, the moment you take it out of the water you can wipe it of and it is dry. Same with oil: it won't soak into the stone.
Just don't forget: the CF is an oil stone that can be used with water.
i would use water, it's less messy and you'll get better feedback off the stone than with oil, which can feel a bit draggy. but before you use anything, as mentioned earlier, you must lap the stone flat.
Thought I would bump this thread. Big fan of Charnley Forests. They are easy to identify and there does seem to be a lot around. I have found them easy to use, effective finishers.
Regarding the question of oil or water - it seems to vary by stone. Fortunately it's pretty easy to tell once you clean them up. The stone on the left performed much better with water, the one in the middle with oil. Once I had stripped the oil out of both, the centre one was much more raspy, even after further lapping and burnishing.
I get a lot more meaningful feedback from the oil stone, which makes it useful for refreshing a blade because it immediately shows up more serious work needed. I use 80% Bisley gun oil 20% WD40.
The water stone works nicely with water only. It puts a very sharp soft finish on harder steels. Great in a progression following Welsh stones.
I have found that the finer Charnley Forests need a progression of lapping, even finishing them with 2000 grit silicon carbine wet and dry on a glass lapping plate.
The maroon inclusions are noticeably softer. When you lap them heavily it looks like the stones are bleeding. I got rid of one stone because there were too many large inclusions across the honing surface.
In comparison with other stones, I have found them less glassy than Llyn Idwal and much easier to read than a coticule.