Diamond Stone Review - Follow Up:
A lot of you have been asking about polishing solution vs. soapy water. This seems to be an ongoing debate, and to be honest, I have no idea what's actually in the commercially available polishing solution.
Some of you have said that you just use water, or you own concoction of isopropyl alcohol and water. I'm no chemist, but in my experience whatever they put into the store bought polishing solution produces better results than soapy water, which may or may not produce better results than just plain water.
That being said, the polishing solution might be overkill for non-racers. Personally, I just use soapy water, and find no reason to try something else, because the results are great.
When I raced, I would use a progression of diamond stones (200 grit -> 400 grit -> 800 grit), which is something I don't do for my powder/mid-fat/all-mountain skis. When tuning race skis, I would always use a polishing solution, and there is no doubt that it produced superior results compared to the soapy water. But again, if you're not racing, don't sweat it.
On soapy water, and keeping stones clean:
While the soapy water solution acts as a lubricant, it also has another important advantage: keeping your diamond stones clean!
Every time you run your diamond stone down a ski edge, a weird black gunk starts to accumulate on the stone, and on the ski edge. When I tune, I run a wet paper towel down the edge of the ski every 10 passes of the diamond stone. You will be amazed at how quickly that paper towel goes from white to black. I also dip the diamond stone in a cup of warm soapy water, and wipe off any black gunk that is building up on the stone.
If you don't continuously wipe down the edges and the surface of the stone, you won't get a good tune. All that build up will prevent the very tiny diamond surfaces of the stone from coming into contact with the edge. In effect, you will just be grinding around dirt, and not actually sharpening anything.
When to replace a diamond stone:
This is, again, a very un-scientific thing. Some of you have written saying your diamond stones have lasted for years. Personally, I have seen stones last for many seasons. It just depends on how well the stones are cared for. If they are rust and dirt free, they should easily last a few seasons. We're talking about diamonds don't forget; a soft steel ski edge is not going to wear down a diamond. What will happen is that the diamond dust, or whatever it is on the surface of the stone, will get scraped off over time. This is why it's important to use aggressive grit (100 to 200) stones on heavily burred or damaged edges, otherwise the cutting surface of the stone will just be scraped off. Again, think sand paper.