LOS ANGELES — In a sprawling, white-on-white lab here that looks like a set from Stanley Kubrick’s “2001: A Space Odyssey,” a British scientist named Thomas Learner recently lifted the top from a small box of slides, the kind that usually contain microscopic samples of bacteria or chemicals.

But this was a different kind of lab, and the slides were coated with dozens of shades of dried acrylic paint, at once as ordinary as house paint and as precious as rare isotopes. This is because the acrylics had been taken from the Santa Monica studio of Sam Francis, the abstract painter, who died in 1994 and who, like many artists of his generation, had largely abandoned the oils that had been the medium of painting for at least five centuries. Instead, he turned to their modern successors: acrylics, enamels, alkyds and many other substances that are more synthetic than organic.

The new paints, which began to emerge in the 1930s and made their way into many studios by the 1950s, allowed artists to do things they couldn’t do with oil. Morris Louis used thinned acrylic to stain, rather than coat, canvases, creating an ethereal effect. Jackson Pollock used gloss enamel because it poured and dripped the way he wanted. Bridget Riley and Frank Stella both used ordinary house paints, Mr. Stella because they “had the nice dead kind of color” that he wanted, right out of the can.

Image A rack of paint samples used for testing at a laboratory at the Getty Conservation Institute. Credit... Monica Almeida/The New York Times

But while conservators have inherited generations’ worth of knowledge about oil paints, they know comparatively little about synthetics and how to protect the masterpieces created by using them, many of which are rapidly approaching the half-century mark.