Quote Originally Posted by superfly
The Norton is as flat as it can be leaving the factory cutting (or leveling) machine.
Nenad
I had a Norton 8k that was arched like a banana, though not nearly as exagerated. I had to sand on it for a long time ( on 1/4" glass plate ) to get it flat. I would suggest you watch Brian Donofrio's videos; they're excellent, and worked well for me. You can test the flatness by placing the stone up against a wet plate of glass and feeling how well it 'sticks'. Be careful not to let go of the stone completely, you wouldn't want it to drop.
E