As I recall, this process, old as it is, is also one of the most permanent - that is, the images will last an extremely long time. I’ve been shocked at how the 1950’s and early 60’s color photos that I have in my family album, always stored in a very cool and dark place, have deteriorated.
Daguerreotypes should last for centuries! I have collected dozens of Daguerreotypes and examined them under a microscope. The image consists of tiny beads of mercury condensed onto a silvered surface. Even when tarnished, as most have, the mercury image remains and can be revealed by chemical processes. Never attempt to clean one, the images smear! Hundreds of Daguerreotype are for sale on eBay any given day.