Thanks guys, have ordered a (hand) smoothing plane and sharpener.
Hope it doesn't buckle too much with the bracing but it's well seasoned and doesn't have to be completely flat. Warped=character, right?
Thanks again.
Firstly thanks for all the replies. Sounds like just ploughing on with the ROS isn't the way forward.
I don't have a hand plane but I do have electric plane with variable depth. This also has rotating blades so will leave milling marks of its own, but if I keep the depth very shallow and go...
Got a smashing piece of elm - a vertical slice through two big burrs and the edge of the trunk. I've braced and treated the back and am trying to get the front smooth and clean. There's some dark stains and milling marks I can't shift even giving it some well with 60 grit on a ROS. The surface...