Magnetic memory of oil paintings

The color in oil paints is obtained sometimes from magnetic minerals. This fact implies that oil paintings could present an intrinsic magnetization. Magnetic imaging of an oil painting consists in the measurement of magnetic flux related to the magnetization of the painting. In this report results of magnetic measurements show that oil paints from different manufacturers (Maimeri, Pebeo, and Grumbacher) are magnetic. The magnetic imagings of four similar oil paintings done with the same visual color, obtained using different mixtures of oil paints for each painting, were different. This shows that the magnetic imaging can be used as a fingerprint for the oil paintings. Magnetic imaging was obtained for oil paintings done by Oswald, Bianco, and Timoteo, all of them are Brazilian painters. The imaging obtained in measurements at different times was always the same, showing that the magnetic images are stable. This leads to the conclusion that magnetic imaging would be a common authentication technique of paintings.