There are small protrusions on both sides - about 0.2mm high and 3mm x 60mm - obviously from the grinding wheel. In 30 minutes, grind them x-coarse and then coarse with DMT. Using a permanent marker, draw a grid on the stone surface and then set it in place. Both sides are high in the middle - a gradual sag towards the edge of about 0.6mm and 0.4mm deep. After 2 hours 1 side was almost flat except for 2 sagging edges at 0.1mm x 5mm x 75mm deep and 0.1mm x 3mm x 40mm deep. The end result is pretty smooth, almost mirror-smooth. I think the grit on my partially lapped surface is between 5K and 6K.
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