The History of Printing Including Flexographic, Lithographic, and Offset Printing
In this installment of the history of signs and printing, I’ll talk about the vast improvements from the mid-1800’s until late in the 20th century. And where the two trades intersected to create a significant change for many sign makers.
A Little Recap
To recap the previous three articles on this particular topic, we’ve talked about how signage came to be used in the West and the wood display gave way (mostly) to electrical and neon in the past 100 years or so. This history has never been so fascinating – much of this information is new to me, so I hope it is for you as well!
While this is part 4 of this series, it is really the second part of this series’ history and how manufacturers eventually came to integrate print technology to visual graphic displays.
The last major improvement we talked about in the last article was roll imprinting, in which large rolls of media could be imprinted at high speeds. The last improvement in this process we talked about was in 1863.
I’m going to backtrack slightly to 1796. A print process called Lithography was developed by an innovative Bavarian author by the name of Aloys Senefelder. The reason I am backtracking to this method is because it became one of the methods used by manufacturers later, or at least in part.
In Lithography, chemicals are used to create an image. Without going into the gory details (which are really above my head and I’m just not into chemistry – I just like what it can do!), we’ll just say there’s some positive and negative images and it produces a very nice print. Today, most books are printed using offset lithography, or offset printing for short. Posters (large runs), maps, packaging, and newspapers are also produced with this method, as well as some signage.
Major improvements in Lithography came later into the 19th century with the addition of color (chromolithography). This process is reputed to be the antecedent to 4-color process which is the basis for most color printing today.
Another improvement was the addition of offset print technology to lithography, in which the inked plate was transferred to a rubber blanket, and then to the substrate such as metal or paper or plastic. Again, there’s some chemicals and water used in this process that I won’t go into, but this improvement is still used to this day in producing books, packaging, and many other printed items at high speeds.
Another innovation that is known today is the Flexographic printing. Initially in 1890 when the first rubber pressing plates were used with water-based inks, the results were fast but smeared too easily. New aniline inks were developed within 15 to 20 years that worked great, particularly with food packaging. The process was called “aniline printing” at that time, but the inks were classified in the 1940’s by the FDA as unsafe for food packaging, and although new, safer inks were developed in 1949, the food industry shied away from aniline impressing, so in 1951, Frank Moss renamed it to flexographic printing, and this category was reborn.
In the 1990’s, rubber plates were replaced with photopolymer plates, and the graphic quality improved dramatically with this innovation. The photopolymer plates are also easier to create now, and digital “direct-to-plate” technology has been developed which has also made the production process much faster as well. Finally, with these improvements, lithography now rivals offset print quality.
Well, I thought I’d get to signage, but I only brushed up on them one time in this article, so I promise, in the next article we’ll talk more about signs and printing and how it became integrated into the graphic display industry.
The last part of this article can be found here: www.visigraph.com/signs/sign-makers-a-history-of-signs-and-printing-part-5/