Yes, it is possible to flatten a cupped board, although it requires caution and patience to achieve good results. Cupping occurs when a board warps in a way that its edges curl up while its center remains low or concave. To flatten such a piece of wood, start by identifying which side is convex (the side with edges curled up) and placing that face down on your workbench. Apply pressure by clamping or using weights at regular intervals along both edges to encourage flattening over time; moisture might also aid in this process by allowing the fibers to expand and relax. Leave it clamped in this position for an extended period before rechecking the board's flatness. Depending on the severity of the cupping, it may be necessary to repeat this process multiple times until the board lays flat.