Quote Originally Posted by benhunt View Post
No not the white spot (I think that's just dust or something). In the 2nd photo it's more visible, about halfway down the visible surface, near the left edge.

I checked it with a level and it looks flat. Do you still think it would be worthwhile to lap it?
When I first bought my naniwas, there was a top layer of binder that holds the grit together, little to no grit. Once it is lapped away, they worked beautifully. Grid pattern as well would be a good idea. It could be just microns short of flat, but you might as well get it as flat as you can.