Daguerreotype The daguerreotype method was invented in the 1830s by Daguerre, a French painter and physicist. He discovered that exposing an image onto a copper plate coated with iodized silver would produce a lasting image if it was also exposed to mercury vapor and fixed with a common salt solution. Later, other vapors were used. Daguerreotypes are captured on polished silver, making it reflective, like a mirror.
Calotype Talbot moved on to another photographic process in which photographic paper was brushed with a salt solution, dried, then brushed with a silver nitrate solution and dried again, creating a silver chloride. Talbot then added gallic acid, making the paper more sensitive to light.