Plan the move. Some artwork is heavier than it looks, especially if the frame has a glass covering. Decide whether you need two people to lift the painting off the wall; as a general guide, always use two people if the artwork is over one meter on any side.
Place the L-section wooden frame on top of the polyethylene sheeting on the floor. Wash and completely dry your hands, and then lift the artwork off the wall and place it in the L-section frame.
Wrap the excess polyethylene sheeting around the carry case in the same way you would a gift; secure the overlapped folds with tape and ensure that there are no gaps in the wrapping, so that it is airtight.
Store the artwork in an air-conditioned space if possible. This limits the possibility dampness and mold.