Tintypes (ferrotype): The ferrotype, better known as the tintype in America, where it reached its greatest popularity, was derived from the ambrotype [example of an ambrotype below].

and like it depended on the fact that a collodion negative appeared to be a positive image when viewed against a dark backgound. In the case of the tintype the negative was made not on glass but on a thin sheet of iron coated with an opaque black or chocolate-brown lacquer or enamel.. (As the tintype was iron rather than tin,
tintype is a misnomer.) ... A tintype was a unique image and could only be duplicated by being rephotographed.
This one is frequently on my desktop wallpaper:

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