There are many uses for NIR filters; one industry that has been growing for the past decade is art conservation. The infrared examination technique detects highly absorbing carbon-based materials such as graphite, charcoal and ink as well as different types of resin and even materials like bees’ wax. Each substance has a different absorbance profile and, with the aid of IR imaging, it is possible to determine which materials were used in the composition of the artwork. Infrared light partly passes through the upper paint layers of the painting, then a camera equipped with IR filters is used to help determine absorption and reflection of the carbon present in the under-drawing.
By analysing a painting‘s underdrawing, information about the artist‘s technique can be learned, and it is also possible to authenticate attribution in some instances.
