It won’t hurt it. I use my stones dry, and I know Ian does too. He’s the only other person I know that uses stones dry. Maybe some others do too. The reason for oil/water/spit is to keep the metal dust that you ground off of the knife from sticking to the stone, and to help float it away. Too me, it’s messier and too much of a pain, so I just use them dry. When I see metal particles sticking to the stone, I just give it a few wipes with the green 3M Scotchbrite pad, and it’s good as new.