the placement of a light source to one side of the painting at a low angle to the surface, so that the light glances across the painting. This examination reveals surface distortions, such as raised paint or undulations in the canvas.
Light from a light source which is placed at an angle to the object during its examination, in order to emphasise the surface characteristics of the object. This strongly angled light will throw up shadows where uneven surfaces appear, making it easier to see creases, lifting paint layers or other damage to a smooth surface.