Nitrate film stock film festival

Now I'vd heard it all.

In TCM's introduction to The Fallen Idol (1948), a movie starring Ralph
Richardson adapted by Graham Greene from his own short story, the guest
was from the now four decades old ongoing film festival American
Cinematheque, there to talk about having projected this movie. They
still project FILM, but if digital is the best available media, they'll
project video.

To project this film, they had to upgrade the projection booth. Why?

BECAUSE IT'S ON NITRATE (FLAMMABLE) FILM STOCK. In fact, they're having
a festival of nitrate prints, which are shipped around the country from
the Eastman Museum.

There aren't too many movie theaters with the necessary projection
booths that can contain the inevitable fire and not kill the audience.

Nitrate film stock has a silver sheen to it but you'll really notice if
you're in a theater. They claim it's not recreatable when digitized
although I thought it looked good on tv. I'll have to step into
my time machine.

I had no idea that this was a thing.