Well... my first hone, bought November 2014, was a Norton 4k/8k combo and as all beginners I have probably mistreated it a little in its first few weeks of life. It is a very nice stone from my perspective and I have used it to successfully turn two non-cutting blades into serviceable and useable shaving implements.

I thought I would step into the breach and flatten my stone. Unless someone randomly donates a D8C my way I'm stuck using the flat surface and sandpaper method. Purchasing 10 sheets of 400 grit wet and dry for a festive 3 Great British Pounds, I wetted the surface, made sure my paper was flat and proceeded to move the stone around. As quite a techy guy I have actually lapped copper and aluminium CPU and GPU heatsinks before so I am familiar with the principle of letting the weight of the heatsink (waterstone) do the work as I move it around the sandpaper.

Contrary to my belief, the stone moved around very nicely and did not take very long to lap. The grid lines I applied slowly faded to nothing and both sides looked (personally) better than the condition I received the stone in. All in all it took me maybe 60 minutes from the thought of doing it to getting the flat surface + water, draw my lines, do the business and clean up.

Most proud of my first flattening attempt but most disappointed that I don't really have anything to use on it quite yet as both of my blades are in 'stropping only' maintenance group at the moment.

Apologies for taking up some forum space but I thought I would share the feeling of success whilst it was still fresh in my heart.

To end, what kind of grit paper would I be looking to use to keep a c12k flat? I understand that it is a very, very hard stone and sandpapering flat would probably be considered a day job but I am quite curious as my c12k has a side which is super flat and another which needs TLC and would serve as a good practice platform.