I found this stone in an old toolbox, and thought it might be useful either for heavy re-shaping, such as heel work, or as a lapping stone, or both.
Attachment 315706
So I gave it a soak in white spirit and then in alcohol to get the old oil and dirt out of it, and started to try lapping it. The finer side looks pretty level, the coarse side is heavily dished. So, I started the rough-out on a paving slab. Almost an hour later, I have a polished paving slab and stone which is almost where it was when I started:
Attachment 315707
Hopefully the pencil marks in the dishing in the middle are visible.
Question is, how do I level this stone?