Those won't sand out Cletis without leaving dips. You can try Czechman's method, it will work. Also you can try some Oak filler. Many woodworkers use Oak filler to get a smooth finish on Oak. The brand I use is called Wood-Kote paste filler. You can find it at most woodworking stores. It is alot of work to fill oak boards. Those craters are caused by soft spots in the grain or bad planner knives when the wood was run thru the planner. If you can't return the boards I would try the paste filler' especially if you are going to stain the boards. I would sometimes mix a little of the stain in with the paste filler to assure there would be no light or dark spots on the boards. Good luck, Coach Frank

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