Recently we were asked if the image below is of a photogravure plate. We posted the question to some experts and here is what they had to say…
note: The image in ‘blue’ tone is simply the photograph of the plate ‘inverted’ in photoshop to illustrate a positive impression of the plate.
Dave Morrish: I suspect that this is not a gravure plate because if it was, the highlights would be reflective and bright, not the shadows. If it looks like a negative, I wonder if it is a relief halftone plate? A loupe would tell you if the shiny shadow areas are meant to be inked in relief as black. I suspect a halftone pattern would be visible too.
Steven Dixon: It is difficult to tell for sure from the image provided but I suspect that the plate is a photoengraving plate, intended to be printed in relief, since the image is in negative. Are there any clues that it was mounted type high on a printing block? Nail holes around the edge of the plate or evidence that it was glued down to block or something like that would mean that the plate was made for printing in relief rather that intaglio.
Lothar Osterberg: It’s hard to tell from the photos what the plate is, but it could be a photogravure.
More general, the only way to see if a copper plate is a "real" photogravure plate or a photo etching is to look at the plate with a good magnifying glass and raking light across the plate for some telltale clues:
-If the plate has an uneven grain pattern (resulting from a dustgrain aquatint), it is likely a photogravure.
-If the depth of the etched areas varies from highlight to shadow areas it is definitely a photogravure. (The darkest areas would be the deepest)
-If the plate has evenly spaced dots or lines, it can be either a photo etching (a halftone process) or photogravure.
A.Only if the depth of the etched areas varies from highlight to shadow areas, and the size of the dots remains the same throughout the plate, it is definitely a photogravure.
B.The even dot pattern was exposed rather than achieved by a random dustgrain aquatint. It was probably printed mechanically (rather than by hand).
-If the depth is the same throughout the plate, but the size of the dots varies, it is a photo etching plate with a halftone.
Peter Miller: I don’t know why anyone would make a negative photogravure plate, as the print made from such a plate would also be a negative (laterally reversed). The darker parts of the plate would print darker, the lighter parts as highlights. It’s hard to tell from the emailed images whether there is a dust-grain structure on the plate or not. Examining the plate with a 15X loupe would tell you that. Perhaps someone who knows more about what people were doing in Germany could help identify the plate.