Start Dating pewter plates

Dating pewter plates

Plates engraved in wood continued to find use in printing application through the late-medieval and early-modern periods.

Early 19th-century work on production of chemically etched letterpress printing plates antedated, in many instances, the invention of photography.

In the first type of printing, a uniform film of ink is distributed over the surface of the plate and transferred from the individual image elements to the receiving paper surface.

In the second, the plate is flooded with a low-viscosity (thin) ink, then wiped with a blade (doctor blade) to remove any ink adhering to the surface.

Without drying the film of collodion, the plate is placed in the camera and exposed, followed by development in ferrous sulfate solution and chemical “intensification” to produce an image of greater opacity.

The image consists of deposits of metallic silver and other heavy metals imbedded in the collodion layer.

In this process, a glass plate is coated with an alcohol–ether solution of collodion (cellulose nitrate) containing potassium iodide.

While still wet, the plate is immersed in a silver nitrate solution, producing light-sensitive silver iodide in the collodion layer.

Though this basic discovery was of historical importance, it did not bring about the immediate use of photoengraved images for printing, and many other attempts to produce engravings by exploitation of the photosensitivity of various natural compounds were made by experimenters in Europe and the United States.