How is a facsimile produced?
In a first step, the three primary colors blue, red and yellow are filtered out and digitized using an electronic scanner on the slide of the original. This information is then written onto film by a laser, creating a separate sheet for each colour. It is important to adhere to the format of the original manuscript when exposing it at this point. Only later are the three colors mixed using halftone dots that are not visible to the human eye.
In addition to the three colors blue, red and yellow, you also need the color black, since the technology is unfortunately not yet advanced enough to produce all color nuances from the primary colors. The black also allows the laser scanner to work out certain contours better.
There is now also the option of obtaining the required data directly from a scan of the original, without first capturing it on a slide. This makes color matching much easier and the digital data can be transferred directly to the printing plate.
Since the scanner can only detect different colors, it is not possible to particularly identify the materials gold or silver. Rather, only certain color values are shown for these precious metals. This is where the manual work begins: True to the original, the silver and gold parts must already be traced in the template.
In order to obtain the actual printing forms, the film recordings of the individual pages are put together schematically, as in the production of traditional printing plates, so that the individual printed sheets are created in accordance with the composition of the original manuscript. The film of the pages that belong together must be combined for each colour.
This assembly process also harbors the greatest difficulties: Since the printing plate has to be exposed precisely, the developed image of the film is transferred to the plate. Thanks to modern technology, this step of assembling the individual pages of a printed sheet can now be done on the computer.
The exposed printing plates are finally inserted into the printing machine and individual rollers are used for the different colors so that the exposed areas can absorb them. The color is transferred to the paper using another roller and a rubber cloth. However, this process must be repeated for each color to create the final, true-to-original image.
The metallic colors silver and gold can either be applied by embossing techniques and the application of metal foils or rubbed in with metal dust as in screen printing. This last step is also the most complex and requires a high level of manual skills and knowledge.