Hi Steve, I always use diamond stones for this job. I would recommend starting with a fine grit stone first as this will show whether it is flat or not. If you use the fine grit first and there are areas which don’t become scratched, then you know it isn’t flat. Once you’ve done that, use a coarse grit stone to get the surface scratched all over. You can then use finer and finer stones and finish with a water stone when you are ready to polish. Regards Tom.
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