Dating old photographs

It was perhaps the most acutely hazardous of all the several highly toxic chemicals originally used in this and many other early photographic processes.

One unusual piece of tintype equipment was a twelve-lensed camera that could make a dozen Each tintype is usually a camera original, so the image is usually a mirror image, reversed left to right from reality.

The areas with the least amount of silver, corresponding to the darkest areas of the subject, were essentially transparent and appeared black when seen against the dark background provided by the lacquer.

Dating old photographs-82

Chemical treatment then reduced the crystals to microscopic particles of metallic silver in proportion to the intensity and duration of their exposure to light, resulting in a visible image.

The later and more convenient dry process was similar but used a gelatin emulsion which could be applied to the plate long before use and exposed in the camera dry.

One or more hardy, lightweight, thin tintypes could be carried conveniently in a jacket pocket.

They became very popular in the United States during the American Civil War.

In 1856 it was patented by Hamilton Smith in the United States and by William Kloen in the United Kingdom.

It was first called melainotype, then ferrotype by a rival manufacturer of the iron plates used, then finally tintype.

The tintype was essentially a variant of the ambrotype, replacing the latter's glass plate with a thin sheet of japanned iron (hence ferro).

Ambrotypes often exhibit some flaking of their black back coating, cracking or detachment of the image-bearing emulsion layer, or other deterioration, but the image layer on a tintype has proven to be typically very durable.

The glass was either of a dark color or provided with a black backing so that, as with a tintype, the underexposed negative image in the emulsion appeared as a positive.

Tintypes were sturdy and did not require mounting in a protective hard case like ambrotypes and daguerreotypes.

This ability to employ underexposed images allowed shorter exposure times to be used, a great advantage in portraiture.

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