On Tuesday, the Lawrence Livermore National Laboratory, a federally funded facility outside San Francisco that focuses on nuclear research, released 63 rare, restored and declassified nuclear-test films. 

The films, uploaded to the lab’s YouTube account, are part of a trove of some 10,000 that have been in storage since they were originally shot between 1945 and 1962, and had been held in secure vaults since then. 

The initial release is just a fraction of about 750 that Greg Spriggs, a physicist at the lab who has worked on the project for five years, declassified on Tuesday. And even that number is small compared to some 6,500 films that have been found of the 10,000 that were estimated to have been shot at the height of the Cold War. 

The goal in preserving and digitizing them, Spriggs said in a news release, was to keep the films for future study, lest they decompose and disappear forever. 

“You can smell vinegar when you open the cans, which is one of the byproducts of the decomposition process of these films,” Spriggs said. “We know that these films are on the brink of decomposing to the point where they’ll become useless. The data that we’re collecting now must be preserved in a digital form because no matter how well you treat the films, no matter how well you preserve or store them, they will decompose.”

What that means for viewers of the lab’s YouTube account is a lot of mushroom clouds. Like this explosion named Harlem, which occurred off Kiribati in 1962 in a series of tests known as Operation Dominic. 

Or this explosion, part of a series of tests at the Nevada Test Site that took place in 1955 that was known as Operation Teapot. This particular explosion was called Tesla.

The United States is the only country to have ever used nuclear bombs during war. In 1945, at least 100,000 men, women, and children were instantly killed when bombs were dropped on Hiroshima and Nagasaki, in addition to tens of thousands more who later died because of the bombs’ after effects.