Hand Tools Archive
..if you're dealing with the more typical soft arkansas stones that look like a bunch of sandy particles stuck together, they tend to go in coarseness with density pretty well, but unless they're abraded, all settle in a little.
When a stone is the pike mine type, or what we call a "real washita", I can't draw as big of a connection with hardness and fineness, and in my opinion, the pure white stones often have less cutting power than some of the more mottled stones even though they're lighter. They have a lot of cutting power when they're first abraded, but seem to run out of steam earlier. If a washita stone is almost entirely pore free, it looks like a chunk of solid earwax and can be relatively fine and strong cutting at the same time (but it won't cut strong like any of them freshly abraded).
In all my fits of buying, the only thing I can really say is the rules sort of hold true and then beyond that it's which vendor's mine. As mentioned previously, dan's softs tend to seem more like hard stones to me. Natural Whetstone usually has coarser softs in the 2.3-2.4 SG range, but I have only bought perhaps 4, so that may not always be true. Their stones are more gritty feeling (the softs) and dan's are less strong cutting from what I've had and are better suited between fast and fine stones.
Brand isn't always a safe way to go, either. Many of the old black stones that norton sold (more common for me to see trans stones of the old type, back to when they were mostly pike branded through more recent) were dark gray translucent looking - they have a different feel than a true black stone, more like a translucent stone. the feel difference is small, but the owner of "natural whetstone" apparently doesn't have particularly good black stones, but he does have good dark gray translucent stones that are high density and have good cutting properties. He calls them "black trans".
And then other times, I've seen norton vintage stones in boxes that were true black stones. I think dark gray and black can sometimes reside together and you can get stones that are a mixture of the two, also. The're close enough when pore free that it doesn't matter unless they have the one odd characteristic of some black stones - releasing the odd clump of particles here and there, which feels the same as a stone with a contamination problem, and then nothing for a while, and then again (I've had that with halls black stones, and I think they're preyda brand now).
I have a chunk of earwax stone labeled by the carborundum company (it's obviously pike washita) - i'll measure it and see what it is.
Point being with all of this that while visual and density characteristics can be a decent predictor of behavior of the non-pike washita mine stones, comparing a pike washita stone to another based on density doesn't always yield expected results and comparing a 2.35 SG soft arkansas, for example, to a washita with the same density will never really yield a stone that has similar properties - the washita will always present a finer edge once stropped in terms of how easily it catches hair and shaves it.