Cave Paintings
In the early 80’s, DeLorean factory workers hid messages on the inside of the panels, usually the doors. These were not discovered until years later when owners started taking the cars apart. Some are still undiscovered.
They have been nicknamed Cave Paintings
I put notes, information and stories on the back of my paintings, related to the painting. When a picture is framed, this back is covered with paper and thus hidden until years later, the picture gets reframed.