Here is a picture of boards cut from a log. What I've found is the postion in the log that was milled will make a big difference on how it preforms when applied to a hive or box. The board will always cup to the center or heart of the tree. The grain of the wood towards the outside of the tree will have closer grains which will dry faster and curl. By putting the heart side of the board to the outside of the box will cause the board to draw into the frame of the box and not the opposite direction which will cause gaps after a period of time in dry weather.