Oil-canning

Origin

In reference to the technique used to operate an oil can, holding it between the index and middle fingers while applying pressure to the bottom to pump out oil.

Full definition of oil-canning

Noun

1. (roofing) A moderate deformation or buckling of sheet material, particularly common with flat sheet metal surfaces. Typically caused by uneven stresses at the fastening points. This terminology also refers to the popping sound made when pressure is applied to the deformed sheet forcing the deformation in the opposite direction.
2. (manufacturing) The movement of a perceived flat surface due to the application of an external force. Caused by unequal stretching of the material inside the surface of the panel while retaining the perimeter. This occurs in home canning, where during the cooling process the lid of the jar is pulled or "popped" down, assuring the lid has sealed to the jar. Membrane buttons on electronic devices give this sensation as well.