The oval diamond steels, and more especially , the finer grits, really benefit from a decent cleaning. I use Dawn detergent, just a little on my fingers and then wiped all over the steel. After that I put a LITTLE wter on my fingers and start rubbing the steel and when the steel gets good and grippy, it's clean. Never throw away a diamond steel that doesn't seem to cut any more. Once the diamonds get worn some the steel clogs more easily and takes a little more cleaning to get it back to grippy and cutting decently. An older steel, like described, tends to be a very good tool for the hard knife steels and more so when you want a finer edge on them. I hav found that for CPM M4 blades, which re usually very hardand very tough, that it puts a nice edge on them. I suspect that the super hard steels like Maxamet, Zmax and Z121, above 63/64 would also really like a well worn diamond steel. Those steels would have to be nearly impossible to sharpen decently without diamond tools. I wishI have one to find out.