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the ess entials

brooklynmuseum:

An Egyptian painted mummy shroud is undergoing an exciting conservation treatment. Over the next few months, Rita Berg will be discussing various stages along the way. Our last post focused on microscopic examination. Today’s post will address the identification of Egyptian blue using visible-induced luminescence (VIL).

Egyptian blue is one of the earliest known synthetic pigments, first produced around 2500 BC. Its brilliant color is often seen in decorative blue glazes of ancient Egyptian ceramics. The pigment was also used in wall paintings, panel paintings, and textile decoration. The unique luminescent properties of Egyptian blue in the near-infrared spectrum of light can be used to identify even the smallest traces of the pigment in works of art.

This technique is called visible-induced luminescence (VIL) and involves shining a bright LED light onto the surface of an artwork and taking a photograph using a camera that has had its filters altered to be sensitive to the near-infrared region of light waves (approximately 910 nanometers).  To the naked eye, the artwork appears normal, but the specially filtered camera captures the intensely bright emission produced by Egyptian blue in the near-infrared region.

Posted by Rita Berg

(via wild-nirvana)