I also made my wife this wine rack . It is made from a 50 year old cross beam from a power pole. What you see is not grain , it is weathering marks . I ran it thew my planner taking off very little because the pattern wasn’t that deep. Then I put 4 coats of polyurethane sanding in between coats with fine scotch bright pads . I could only drill the holes about 1-1/2 " deep . Then chisel the center . Had to do this 3 times for each hole .