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X-Ray Vision: Not Just For Superheroes


Do you know what the x-rays are?, Digital ID 1519277, New York Public LibraryIt's time to be blinded with SCIENCE...

We do some pretty cool things in the Barbara Goldsmith Conservation Laboratory, but one of the coolest happened recently when we used x-rays—or rather X-ray fluorescence spectrometry (XRF), to be exact—to help us identify colored pigments on some very rare fragments of prints from the 15th Century known as stencils.

We were very lucky to be visited in April by Thomas Primeau, Head of Conservation at the Baltimore Museum of Art, who brought with him his portable XRF spectrometer. Tom has been researching print stencils, and came to the New York Public Library to examine the rare examples in our collection.

Tom Primeau, Head of Conservation, Baltimore Museum of Art, in the Goldsmith Conservation LaboratoryTom Primeau, Head of Conservation, Baltimore Museum of Art, in the Goldsmith Conservation LaboratoryAs part of his research, Tom wanted to use his XRF spectrometer to discover what pigments those early printmakers used to color the prints. In XRF spectometry, x-rays are used to detect and measure the energy of particular electrons in a substance. Then, the specific characteristics that were measured are used to identify that substance.

The fragments of stencils we examined are currently in the Prints Collection at the Stephen A. Schwarzman Building. They are pieces of a much larger woodcut print known as Man of Sorrows. We have only fragments of the print, and no copies of the larger complete image are known to exist. It was created by an unknown artist sometime in the 1400s.

What makes the stencils so rare is that they were waste products, essentially mistakes made by the printer that were intended to be thrown away.

The printer reused mis-printed or badly-printed images, cutting them into pieces to be used as stencils. The stencils were used in the hand-coloring process, to rapidly add blocks of color to other black-and-white prints. In this image, you can see where the hole cut in one print fragment corresponds to the colored area in another fragment.

Stencils from this time period are extremely rare, and these in the Prints Collection are some of the very few known to exist in the world. Their discovery is an equally fascinating story. In the 1930s, they were uncovered by a bookbinder at the New York Public Library as part of another book that had been sent to the bindery for repair. A 15th Century bookbinder had layered the waste prints to make the stiff board covers that were then covered in leather. It was only when the covers were removed that the insides were found to be made up of these print fragments. They were carefully separated and identified. It is thanks to this eagle-eyed former NYPL bookbinder that we have these prints today.

XRF Spectrometer in actionXRF Spectrometer in actionIn our modern-day conservation laboratory, we continue to discover information about these rare prints. To conduct his experiments, Conservator Tom Primeau positioned his XRF spectrometer over different colored areas of the prints, and the equipment collected the data. The spikes visible in the graph correspond to different elements on the Periodic Table. With proper analysis, Tom will be able to identify the colored pigments used on the Man of Sorrows print.

Tom will publish his results in an upcoming publication. His efforts will help other conservators and scholars understand more about the materials and methods used to make prints during this time period.XRF graphXRF graph


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