“I want to sandblast some strips of wood that are 12mm wide and 1m long. Basically, I need the whole top surface remove, and importantly the wood needs to be completely level after the sandblasting has been completed. I was wondering if the sandplasting could be completed in one pass, and also aproximately how long would it take to sandblast one strip?”
Sandblasting will gouge the wood. For example take a piece of pine; it has white wood, and darker wood. The dark wood is harder than the white (sapwood), so it will resist the sand more–but the sapwood will get dug out. You are much better off chemically stripping the wood, or running it through either a planer, or a belt sander.