The Lick sent successful images to photogravure (engraving) companies around the country, seeking out the most skilled photographic technicians to create faithful duplicates of the images they had worked so carefully to create. The took the original image as unequivocally objective and wanted the reproduction to precisely match the original. Yet astronomers could not know what many of these distant (often invisible) objects actually looked like; they were working within certain ideas about what they should look like and how to best represent them to the public. They wanted to create visually stunning photographs as well as factual pieces of data.
Even the best images were often difficult for the printers to reproduce. As you can see with the plates displayed here, the actual object under observation often measured only millimeters in diameter on the plate. The printer was to transfer the image on the glass plate onto a copper plate or another kind of glass plate, which was then coated in ink to produce a print. The creation of the second plate positive was a long process which involved re-exposing the negative onto photosensitive materials--materials that were thicker, more viscous, and more unstable than the chemicals used to create paper prints now; and then dipping the plate in a bath of acid in order to etch into it the light portions of the image, leaving a raised image on the plate to be coated in ink. Accordingly, the very materiality of these materials and the difficulty of manipulating them often interfered with the printers' attempts to carry the exact resolution and sharpness of the original image over to the second plates. Edwards Barnard's book on his experiences with astrophotography covers the printing process in detail. To read more about the reproduction process, see Alexander Pang's article on astrophotography at the Lick, cited at the bottom of this page.
The archives contain a large series of correspondence, much of which consists of letters between Lick directors and various photogravure companies. Their letters expressed many complaints--strange gradations in the solar corona, loss of light or structural detail, the lack of clarity and contrast, the "thinness" of the shadows and dark sky behind the object. These complaints are aesthetic in nature; and as Pang has noted, they often invented new aesthetic discourse or concepts--like "nebulosity" and "snappiness"--to describe to the printers how a cosmic body should appear. Correspondence would often last for several months and become quite heated as the Lick's directors insisted that the printers try again and again--in order to darken the background or to bring out important details from the original image, like the fainter light in a nebula or the lines in a comet's tail. Yet they would then criticize the printers for retouching the images too much and accordingly stripping them of their objectivity.
As noted above, our research in this area builds on the work of Alexander Pang.