Prior to the invention of the window envelope in 1901 by Americus Callahan, there was no real need for an inside tint as the sulfate paper at the time was so thick that one could not see inside the envelope. It was really not until 1903 that Julius Reigenstein, the owner of Transo Envelope Company came up with the idea of using an inside tint as a security device and you can see them on early window envelopes. This inside tint prevented someone from looking just below the address field to see the amounts or bank numbers on checks. So inside tinting was really a natural evolution of the window envelopes.
Most printing prior to the 1950's was accomplished using oil based inks that had to be treated with heavy solvents. The inside tinting that they produced using a special etched roller gave the inside of the envelope an marbled look and again, offered some identity protection. The process used to create the window involved rubbing a special type of oil on the face of the paper to make it translucent, at the same time, it impacted the opacity of the paper so you could "see inside" or through the paper unless the inside was treated with a design that negated this effect.
The earliest example I have of an inside security tint is an envelope used at the White House during Woodrow Wilson's administration. The inside tint was used to insure that no one read the contents of the letter and Wilson used window envelopes at the time to save on readdressing time given the quantity of correspondence his administration produced.
Business envelopes made prior to 1930 only limitedly contained inside tints, Again, primarily for protection of contents, especially checks. When the Federal Reserve system came into being in the 1930's, banks were required to place a FRS clearing number on the base of the check stock. Again, many businesses used inside tints so this information could not be read.
Companies in the 30's started to vary their tints. Early telephone bills and other types of bills, where the company wanted to promote the brand, used inside security tints and logos. These later came into prominence in the 50s and 60's. Companies like Sears, Montgomery Ward, ATT, Magazine Publishers, and the like all used security tints and other devices on their envelopes on the inside.
No one has ever cataloged the host of security tints and logos that were used on the inside of envelopes. No one but Transo envelope company, which started the process, ever patented or copywrited these markings so they evolved through standard usage. The Guttman company of New York pioneered a device called a "Tint-a-Web" which attached to an envelope machine and applied the security tint and markings. Early airmail envelopes had security tints or designs.
Security tinted envelopes first appeared in Europe in the 20's and due to the wood free papers that they used were used often and still used today on envelopes used for billing and personal correspondence.
The color used most often is dark blue, sometimes green but the idea is a visual barrier to the envelope.
This is what I have in my records. I only wish I had more time to explore this subject further but I hope this is helpful.
Please feel free to quote me. The Transo Envelope Company ceased operations in 2002 and no longer exists. You can find out more about them in my book and the information on the inventor of the window envelope under Outlook Envelope...
Maynard H. Benjamin, CAE
President and CEO
Envelope Manufacturers Association
500 Montgomery Street, Suite 550
Alexandria, Virginia 22314-1565
Phone: +1 703-739-2200
Fax +1 703-739-2209
The History of Envelopes 1840 - 1900
by Maynard H. Benjamin
© Envelope Manufactures Association
EMA Foundation for Paper-Based Communications