Have norton stone kit and a chinese 12k. Even though the pencil lines are removed during lapping, done several times on each stone, the stones are not perfectly flat. Using the lapping stone which came with the norton kit but that is not perfectly flat either. Other lapping mediums or suggestions would be appreciated.
Try the DMT 325. I got it from SRD (Straight Razor Designs) and it did a wonderful job on my Naniwa 1K, 5K, 8K and 12K.