It is a scanning technique that uses extremely high frequency waves to penetrate dense surfaces. Originally employed in the search for petroleum reserves, it is now used in art restoration. The beams can penetrate layers of paint introduced in varying degrees by artists to create particular effects or it can also plumb, without causing damage, layers of wear-and-tear over the years. Without the signal processing, researchers might only be able to identify layers 100 to 150 microns thick. But using the advanced processing, they can distinguish layers just 20 microns thick. Paintings done before the 18th century have been challenging to study because their paint layers tend to be very thin. Beyond old art, the non-destructive technique also has potential applications for detecting skin cancer, ensuring proper adhesion of turbine blade coatings, and measuring the thickness of automotive paints.
