Besides the graphics of the film promotion materials these represent, and the stylish humor and campiness of the artists who make them, these are also original and delicate objects. The printing process used in reproducing the posters and lobby cards have bearing on its value. At a later date we will talk about the history of the different printing processes used in Mexico and Spain, where most of these were produced. For now, we'll briefly discuss what types of printing may have been used and how to identify it.
|Magnified off-set dots|
Mechanical off-set printing is the most common process and the most contemporary. Some are of the opinion that it is also the least valuable process because the prints do not hold their colors well. It's good to have a loupe or magnifying glass to examine the detail. Under magnification, off-set printing will have very regularly spaced or mechanically spaced looking color dots. Be sure to examine the entire print, because this characteristic off-set ink dot pattern may be visible in one area more so than another. Off-set came into wide usage in the 1930s. Although it is possible that Mexico may have not had off-set printing in general use until sometime after that, the presence of off-set dots may help you roughly date your poster or lobby card. Websites about movies are very complete, so you may be able to date the poster or card by looking online. However, it is always possible that you could find the rare or obscure movie promotional material that will not be easily identified, thus knowing the printing process used may help date it.
|Gravure, enlarged from card at left|
The oldest movie posters were done with stone lithography. There was a point when studios may have used lithography for some of their posters and off-set for others. However, if you identify a poster as a lithograph, it is possible that it could be one produced prior to the 1930s, and be quite old. Stone lithography came into use in the 1880s, with later color posters needing a different stone for each tint. Often an early black and white litho would have had color added by hand after printing. In this case, with a loupe or the naked eye, it would be possible to see brush strokes. Litho is a complicated process in which the artist uses a number of tools, materials, and chemicals to etch their design directly onto a limestone, which becomes the printing plate that gets inked, and the paper pressed onto it to create the image. Limestone plates can be resurfaced and re-used. The artist can surface the plate to have a fine or rough grain. This grain is an important identifier of a litho. With close examination, a lithograph will have an irregular and very organic-looking print grain. Just what you would expect to see in a poster printed on a natural stone surface.
Lithography process video:
Thanks to Wiki, the great website "Printing for Dummies," and the excellent book How to Identify Prints: A Complete Guide to Manual and Mechanical Processes from Woodcut to Ink Jet by Bamber Gascoigne