In a behind the scenes video worthy of r/oddlysatisfying, the Museum of Modern Art (MoMA) joins expert conservator Lee Ann Daffner to show you what it takes to clean, rehouse, and ultimately save one of the oldest photographs on Earth from being eaten away by its own chemistry.

The photo in question is actually two daguerreotype photos captured on a single silver plate by French aristocrat Joseph-Philibert Girault de Prangey in 1842, just three years after the daguerreotype was introduced to the world. Girault de Prangey’s photos are some of the oldest and most prized in MoMA’s collection, but this particular image was being overwhelmed by tarnish.

Because daguerreotype plates are made of silver, just like silver jewelry, they can tarnish when they come into contact with Sulfur. What’s more, you can’t just go to town cleaning them. As Daffner explains in the video, daguarreotypes are actually exceptionally fragile.

“Unfortunately, the image literally just sits on the surface of the silver plate and can be very easily wiped away with a brush,” says Daffner. “Preservation is paramount for these plates.”

To that end, Daffner removes the plate from the housing that is causing it to tarnish, very carefully cleans the dust and debris off of the top (something we wish they’d shown more of in the video), and rehouses it using special materials that are as chemically inert as possible. It’s actually quite fascinating how much chemistry goes into the process of ensuring this plate will remain pristine for years to come.

“There’s a real art and science to the cleaning,” concludes Daffner. “Not only do you have to know the systems and materials and types of deterioration, but you need to know when to stop.”

If you’re into photo history and photo conservation, or even if you just want to see one of the oldest and most exotic daguerreotypes in the world up close, be sure to watch the full video up top.