A technique called ‘raking light' has been used to analyze art for a long time.Our image of Ancient Greece is inescapably colored, pardon the pun, by having grown up with the austere appearance of its white marble buildings and statues. The technique reveals just how colorful their culture truly was.
A lamp is positioned carefully enough that the path of the light is almost parallel to the surface of the object. When used on paintings, this makes brushstrokes, grit, and dust obvious. On statues, the effect is more subtle. Brush-strokes are impossible to see, but because different paints wear off at different rates, the stone is raised in some places – protected from erosion by its cap of paint – and lowered in others. Elaborate patterns become visible.
Ultraviolet is also used to discern patterns. ...
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