I’m curious about the professional ethics of this. If they couldn’t know until after they uncovered it that it wasn’t covered by Vermeer how did they know they weren’t destroying the artist’s composition? If they didn’t know that how did they make the determination to do it?
The determination used expertise. People with PhD’s in art history and such. Chemists with mass spectrometers. Technicians with sophisticated X-rays. Archivists too.
All working together over the course of years guided by professional ethics and all watched over by bean counters, museum administrators, and public and private funding institutions.
> In light of the many indications that supported the idea that the overpainting had been carried out by a hand other than Vermeer’s, the Staatliche Kunstsammlungen Dresden, supported by the expert commission, decided early in 2018 to remove the layer of overpaint.
> During a restoration and research project that began in 2017 and was supported by a panel of international experts, the team made or re-evaluated X-rays, infrared reflectance spectroscopies and microscopies of the oil painting in the past few years. The backing canvas was also analyzed in detail and research was conducted into the painting’s restoration history. Multiple color samples were taken from Vermeer’s painting and the layers and consistency were analyzed in Dresden Academy of Fine Arts’ Laboratory of Archaeometry (HfBK). These studies played a decisive role in reassessing the extensive overpainting of the Cupid figure in the Girl Reading a Letter at an Open Window. We can now safely state that it was not Vermeer himself who painted over the background, and that the retrospective change was applied at least several decades after the painting was made, and significantly after the artist’s death. A full-surface X-ray fluorescence scan of the painting, conducted with the support of the Rijksmuseum in 2017, confirmed our new findings on the overpainting.
