I bought a 325 diamond plate last year to lap my stones with and after not quite a year thought it was warn out. It really looked like the center was gone or warn down. I was looking to buy a new one when I remembered reading something about cleaning the plates with different detergents. I got to looking and what I had was soft scrub. I used it once and could tell a difference. I used it again today and cleaned it again and it's almost as good as new. Guess I need to do more reading than thinking.