In 1881, a filthy, flaking canvas sold at an auction in The Hague for two guilders plus a 30-cent premium, about 24 euros today. The buyer, Arnoldus Andries des Tombe, acting on the advice of politician Victor de Stuers, had just purchased Johannes Vermeer's Girl with a Pearl Earring, painted around 1665. This deep dive strips away the tote bags and coffee mugs to examine the physical canvas itself, beginning with the Mauritshuis museum's 2018 Girl in the Spotlight project, in which conservator Abbie Vandivere and an international team scanned the painting in a glass laboratory as the public watched.

Their findings rewrote the painting. The flat dark void behind the girl was originally a folded green curtain, painted with organic indigo and weld pigments that faded under centuries of light while the stable bone black beneath survived. Micro ...