Invisible Writing Made Visible: The U. S. Government Printing Office and Prisoner of War Stationery in the Second World War.
According to the Geneva Convention on prisoners of war, each prisoner was entitled to write home to relatives. The convention also severely limited the use of heat and chemicals to detect secret messages on such letters. (3) Significant information on prisoners' locations and labor activities could easily be transmitted through the use of invisible or sympathetic inks made from such common substances as lemon juice, milk, washing soda, baking soda, starch solution, and even human urine. (4) Already aware of serious problems encountered in censorship of German prisoners' mail during World War I, the War Department turned to the U. S. Government Printing Office (GPO) for an answer. (5)
GPO was no ordinary print shop. In the 1940s, most people, if they had any mental picture of a traditional printing plant at all, might have visualized a small or medium-sized town newspaper, including a Linotype machine or a press or two. Large metropolitan dailies took this image up a step to perhaps a dozen or more Linotypes, several large web presses, and lots of support personnel. When we talk about the scope of the U. S. Government Printing Office in the first half of the 20th century, however, we move to another order of magnitude and complexity.
In the 1920s and 1930s, GPO had nearly 200 presses, all letterpress, not including at least thirty-one proof presses, ranging from small job platens to rotary web presses bigger than a Washington, D. C., studio apartment. There were more Monotype and Linotype machines at GPO than in any other plant in the world--more than one hundred Monotype and 129 Linotype machines. (6)
As World War II loomed, GPO was a huge, diverse, and frenetically busy place. Its emphasis on quick turnaround, high quality, and economy begat a culture at GPO that said, in effect, "whatever it is, we make it, do it, and print it here." GPO made its own ink, cast its own type metal, and even built much of its own furniture. One very highly organized and busy supporting division in the "industrialized" GPO was the Division of Testing and Technical Controls (the "testing division" for short). It was set up in 1922 under the administration of Public Printer George H. Carter to carry out the mandate of the Printing Act of 1895, which required the Public Printer, GPO's head, to "compare every lot of paper delivered by a contractor with the standard of quality fixed upon by the Joint Committee on Printing and shall not accept any paper which does not conform to it in every particular." Previously, GPO had used other government facilities to perform this task. (7)
The testing division ensured that all raw materials and component parts produced the best possible performance, starting with paper, the monitoring of which was a statutory responsibility of GPO. It checked type metal constantly and corrected it to very exacting standards, as well as improving its formulas based on test results. It also tested ink, manufactured by GPO at least since World War I, for efficiency, durability, and readability. Metal for platemaking, adhesives for bookbinding, solvents--all were tested, and in many cases improved. The division maintained a staff of chemists, metallurgists, and other analysts, an industrious group that quickly established an impressive reputation in the industry and the rest of the government establishment. It was this unique unit of GPO to which the war department turned to block any attempts by prisoners of war to convey sensitive information to their axis homelands.
Carter was followed by another dynamic public printer, Augustus E. Giegengack, who started out as a Linotype operator in New York and became production manager for Stars and Stripes in France in World War I. Although appointed by presidents of different parties and clearly quite different in temperament, Giegengack and Carter had surprisingly similar ways of handling the work and treating the workforce. Their methods were accentuated by the outbreak of war. The War Department's idea seemed simple. GPO was to develop a paper that would react immediately to any invisible ink by making it visible, without using heat or chemical reagents. The problem was that no such paper had ever been manufactured on a production basis. Large quantities would be needed as soon as possible to prevent the growing number of German prisoners, as well as smaller numbers of Italians and Japanese, from becoming a legion of spies.
GPO proved to be an obvious choice for the department to consult because at the beginning of the war, the Office of Price Administration (OPA) had posed a somewhat related problem, and GPO had produced an innovative solution. GPO was producing a vast number of coupons and booklets for the rationing of all kinds of consumer goods. OPA came to GPO because ration stamps and coupons were prime targets for counterfeiters. The staff in the testing division got to work and, with the cooperation of the paper industry, developed a "safety" paper that ingeniously mixed in fluorescent fibers; while undetectable in normal light, it turned colors under ultraviolet light. GPO continued to work throughout the war on improvements to the papers and the ink, and its analysts were called as expert witnesses to testify in the trials of counterfeiters. (8)
Following that success, the War Department approached GPO Technical Director Morris S. Kantrowitz, Associate Chemist E. F. Gosnell, and paper expert Robert H. Simmons. Along with other GPO employees, they immediately began experiments to create the new paper. Their main concern was to counter the use of the substances most accessible to prisoners. Broadly speaking, these fell into two categories: acid (citric acid in lemon juice, lactic acid in milk, and uric acid in urine) and alkaline (sodium carbonate, washing soda, and sodium bicarbonate, or baking soda). Low concentrate solutions of these substances all could be used as invisible or sympathetic inks. (9)
After extensive tests, GPO's experts developed a paper base with a silicate or clay coating. The coating contained a powder or dyestuff that would react to moisture or any acid water solution by turning green. A second element was added that reacted to alkaline substances by turning red. Ammonia solutions were a partial exception, turning red initially and then green after the ammonium evaporated from the solution. Surveillance tests showed that all of the colors formed by either acids or alkalines would last for months. (10)
The new paper, dubbed Sensicoat by its GPO developers, (11) was soon made to testing division specifications for printing prisoner-of-war stationery and postcards, including directions in German, Italian, and Japanese. Although pleased at their success in blocking information leaks by prisoners of war, Kantrowitz and his staff were less satisfied with other aspects of Sensicoat. Its heavy 56-pound weight, its high cost of 23 to 30 cents a pound, and the faintness of color when written upon by some invisible inks were all negative factors. When the war department informed GPO that it would be placing a large new order for stationery and post cards, the testing division decided to develop a lighter, uncoated, and more economical paper. (12)
Kantrowitz later described the division's approach in his annual report:
Having conceived the idea of depositing an essentially colorless layer of strong, water-soluble dyestuff on a paper sized to receive it, one dyestuff was selected from a group of promising samples. It was necessary that the dyestuff selected possess high tinctorial (coloring) power, be of a neutral shade in the un-dissolved state, and be insoluble in linseed oil, varnish, and in the varnish solvents. Also it had to be appreciably fast to light, acids, alkalis, and the usual oxidizing and reducing agents ... over 400 samples were tested. (13)
The need for an agent to bind the dye to the paper also required extensive research into varnishes and drying oils, resins, and plastics. The final formula was thin enough to function as an aniline press ink while keeping the finely ground dye particles in suspension. The War Department approved samples, then informed GPO that an order for millions of sheets was ready to go. Sooner than expected, GPO had to shift from laboratory work to the production stage.
After more testing, a decision was made to apply the formula by either an aniline or rotogravure press. Both could produce an essentially white sheet with high sensitivity to liquids applied by a pen. To ensure security, GPO began searching for a manufacturer that could produce, sensitize, print, and cut the forms and cards. This one-stop shopping would also be simpler and more economical. One paper manufacturer, the picturesquely named Kalamazoo Vegetable Parchment Company, had everything GPO needed, including an up-to-date ink grinding mill and a good research laboratory. Using an aniline press, workers coated both sides of the sheets with the formula simultaneously, while also printing the stationery. (14) The resulting product--a 48-pound chemical wood writing base paper for the stationery and 188-pound chemical wood Bristol for the post cards--was named Analith. GPO filled the War Department orders for 44 million forms and 25,600,000 postcards at a savings of $192,000 over the previous Sensicoat product, with an accompanying reduction in the number of operations and transportation problems. (15)
The introduction of Analith prisoner-of-war stationery in December 1941 superseded Sensicoat, a fact highlighted by a request from the Canadian Embassy a few months later. The embassy asked the adjutant general of the United States to furnish it with information on prisoners' stationery and was referred to GPO. It seemed that the Canadian government was displeased with its own prisoner-of-war stationery and wanted to develop a better paper. Upon examination, its paper specimens turned out to be Sensicoat. When told of the development of Analith, the Canadian government requested samples and was given the formula. As Public Printer Augustus E. Giegengack noted, "We welcomed this opportunity to be of service to our friend and ally." (16) At this point in the battle of invisible ink and sensitive papers, the Tests and Technical Control staff could have been forgiven for declaring themselves the winners. After two years of hard work, any liquid accessible to enemy prisoners would burst into vivid color when brought into contact with Analith. At the very least, secret messages to the Axis had been greatly reduced--a reduction noticed and acted upon by German intelligence.
As 1944 passed the halfway mark, American censors began noticing something very interesting about packages of food and clothing addressed to German prisoners. A small amount of putty-like material about the size of a kitchen match head began to turn up in various places of concealment. The first shipments also contained tiny pieces of paper with text instructing the addressee to mold the material to the end of a match or other stick of wood and use it as a pencil, although without applying any pressure. (17) Visual examination, steam, and ultraviolet light showed no writing. Bureau of Censorship chemists learned from repeated tests that the putty-like material was a dry ink. Once discovered, its active ingredient was classified as a military secret. When reacting with the reagent amidol, this dry ink would take on a strong color. Although the Bureau of Censorship learned this much, it was unable to develop a means of discovering this secret writing within the rules of the Geneva Convention. (18)
After several conferences with the bureau regarding this problem, GPO's chemists began work on a new paper, bearing in mind that it also would have to retain its sensitivity to fluid invisible inks. Stability and economy also were important factors in their search. Experiments revealed that gallic acid was an excellent sensitizing agent for the most common German dry ink. (19)
Agreeing that it would be impossible to develop a paper equally efficient in exposing all such compounds, Kantrowitz's staff took another look at Sensicoat. In many cases, written characters could be detected visually when written in dry ink on the old stationery. After some study of dull-coated papers manufactured by the Allied Paper Mills of Kalamazoo, Michigan, a GPO chemist was sent to Michigan to work with both Allied and the Kalamazoo Vegetable Parchment Company on this new angle. (20)
After considerable difficulty, GPO devised a method of adding gallic acid to a coating without altering the color of the paper. (21) It achieved even greater sensitivity by adding the acid to the Analith formula with an overprint of gallic acid and two other chemicals. This technique was also less expensive than adding the acid to the coated paper. Kantrowitz described the final product as
An uncalendered, coated sheet processed with a water sensitive formula and with ... great sensitivity to the detection of all types of "dry inks," especially the widely used vanadate type. The writing quality of this paper is as good and the aqueous invisible ink sensitivity better than the "Analith" War Prisoners Stationery which it superseded. (22)
The paper was made at Allied Paper Mills and processed and printed at the Kalamazoo Vegetable Parchment Company only three miles away. By 1945, more than 29 million sheets of new stationery had been ordered at $1.04 per thousand--more expensive than Analith but still a considerable savings over the cost of Sensicoat. (23)
Even after this triumph, GPO kept going. In July 1945, an employee in the Commercial Planning Division, B. Specter, working with Kantrowitz, Gosnell, and others in the testing division, presented a proposal for a two-part form designed such that the part the prisoner would write on and the part that actually would be sent were kept separate, to be cut apart by the censor. Specter wrote,
The letter is so designed that an image on the sheet which is transmitted to the enemy can be effected only through mechanical pressure. The prisoner writes on part of the form, and his writing is duplicated by carbon to another part which was so folded into the form that it became sealed and self-enclosed. Mechanically it cannot be reached without visible change ... Chemically, it is our object to prevent tampering by the self-formed protective jacket which becomes a wrap for the transmitted part ... After the letter is written, the form is cut apart to make two pieces: the inner letter which becomes the mailing piece [and] the wrapper which can be held ... to determine if any attempt has been made ... to transmit a message [secretly]. (24)
This form was almost twice as expensive as Sensicoat, but the War Department was sufficiently interested to put funds toward further experimentation at GPO. Obviously, however, it was a solution that lacked time for implementation, and it appears never to have gone into production.
In addition to the years-long battle to thwart prisoner of war espionage, the War Department came to GPO with other jobs that required the testing division's expertise. Almost immediately after Pearl Harbor, the Army Air Force sought the printing of bombing charts that could be read in all light conditions and withstand extremes of atmosphere and wear. The testing division carried out research on fluorescent printing in cooperation with paper manufacturers, ink makers, and makers of fluorescent pigments. GPO used its newly gained authority to contract with private sector printers to complete the work. However, the printing office and the Army Air Corps deadlocked over the choice of a contractor, and ultimately GPO developed a method that could be utilized in its plant. GPO was commended for its success in ensuring the timely delivery and technical excellence of the charts. (25)
Later, following the passage of the Soldier Ballot Act of 1944, soldiers' ballots for that year's election had to be "readily and positively identified as genuine." The testing division returned to its work with fluorescent inks and successfully specified a process for printing an overall design on both sides of the paper that, although invisible under normal light, would "fluoresce brightly" under ultraviolet light and withstand the action of salt water, heat, and high humidity. (26)
At the war's end, GPO could look back on its efforts with great satisfaction. It had blocked a potentially dangerous flow of information to America's enemies--an achievement shrouded in wartime secrecy, but one gratefully acknowledged by those who knew about the technical difficulties involved. Curiously, however, a surprising amount of information about the GPO's innovations got into the trade press just before the end of the war, causing a minor contretemps between the Bureau of Censorship and the Public Printer. In three speeches Giegengack made in early 1945, "he mentioned that a paper had been Developed ... which would circumvent the use of dry inks by enemy prisoners." (27) The Bureau of Censorship apparently wrote to Giegengack expressing disapproval. GPO responded that "inasmuch as the Public Printer has not divulged any specific methods by which such writing may be made or detected, it might be considered by the Bureau of Censorship that no serious confidences have been violated." (28) There is no record of whether the Bureau considered it in that light, but on January 22, 1945, the Public Printer did receive a letter from Byron Price, the bureau's director. The letter said, in part:
I wish to express my deep appreciation of the extremely cooperative and helpful relationship between your technical laboratories and the representatives of this Office ... The entire progress of the investigation has been most pleasing as an example of the effective and harmonious relationships which can be developed between two government offices with a common objective in view. (29)
GPO's testing division still exists, although under a different name and engaging in very different activities, and the agency continues to take pride in its contributions to the war effort against the Axis. Recognition of the office's wartime activities, kept a secret through the war years, was documented proudly in a postwar history, Public Printing in Peace and War, published in 1947. Among the achievements listed, GPO's work with counterespionage and invisible ink has proved to be one of the most fascinating.
(1.) Arnold Krammer, Nazi Prisoners of War in America (Briarcliff Manor, NY: Stein & Day, 1979) p. vii.
(2.) For an account of German espionage and sabotage in America during World War I, see Jules Witcover, Sabotage at Black Tom: Imperial Germany's Secret War in America, 1914-1917 (Chapel Hill, NC: Algonquin Books, 1989). For a civilian espionage case in which invisible ink figured prominently, see David Kahn, The Reader of Gentlemen's Mail: Herbert O. Yardley and the Birth of American Codebreaking (New Haven and London: Yale University Press, 2004) pp. 33-35.
(3.) United States Government Printing Office, Public Printing in Peace and War: Development and Administration of the War Program by the Government Printing Office (Washington: Government Printing Office, 1947) p. 40.
(4.) United States Government Printing Office, Report of the Technical Director to the Public Printer, 1942-1943, Government Publishing Office Historical Collection, Washington D. C., p. 8.
(5.) Public Printing in Peace and War, p.41.
(6.) United States Government Printing Office, Descriptive Catalog of Machinery and Principal Equipment, 1926, and Descriptive Catalog of Machinery and Principal Equipment, 1941, Government Publishing Office Historical Collection, Washington, D. C.
(7.) Public Printing in Peace and War, p. 39.
(9.) Report of the Technical Director, 1942-1943, p. 8.
(12.) Ibid., p. 10.
(13.) United States Government Printing Office, Report of the Technical Director to the Public Printer, 1943-1944, Government Publishing Office Historical Collection, Washington D. C., p. 13.
(15.) Ibid., pp. 15-16.
(16.) United States Government Printing Office, An Informal Report of the Public Printer, September, 1944, Government Publishing Office Historical Collection, Washington D. C., p. 3.
(17.) Public Printing in Peace and War, pp. 41-42.
(18.) United States Government Printing Office, Report of the Technical Director to the Public Printer, 1944-1945, Government Publishing Office Historical Collection, Washington D. C., p. 14.
(19.) Ibid., p. 15.
(21.) Ibid., p. 16.
(22.) Ibid., p. 17.
(24.) Memorandum to E. E. Morsberger from B. Specter, 23 July 1945, Government Publishing Office Historical Collection, Washington D. C.
(25.) Public Printing in Peace and War, p. 89.
(26.) Ibid., p. 43.
(27.) Memorandum to the Production Planning Assistant to the Technical Director [M. E. Kantrowitz] April 9, 1945, Government Publishing Office Historical Collection, Washington D. C.
(29.) Informal Report of the Public Printer, p. 2.
George D. Barnum is Agency Historian and Congressional Relations Specialist at the U. S. Government Publishing Office. He has written extensively on rare and valuable government documents, electronic dissemination of government information, and the history of the GPO. He presented at the 2014 APHA conference and is President of APHA's Chesapeake Chapter.
James T. Cameron is retired Publications Marketing Specialist at the U. S. Government Publishing Office. He served as GPO Historian from 1982-1984, and currently is Managing Editor at Cameron Editorial Services.
Caption: OPPOSITE: GPO operated the largest Monotype shop in the world, with more than one hundred keyboards and casters. These photos are from the 1940s. The testing division corrected and reformed the 15 tons of type metal used daily in the Linotype and Monotype sections.
Caption: Public Printer George H. Carter, the Progressive Era appointee of Warren G. Harding, served from 1921 until 1934. Mr. Carter oversaw many workplace reforms and improvements, including the creation of the Testing and Technical Controls Division in 1922.
Caption: The testing division also analyzed metals for type and platemaking, chemicals, pigments, inks, and adhesives. This is the metallurgical laboratory in the late 1930s.
Caption: The paper testing laboratory in the GPO Testing and Technical Controls Division, late 1930s. At the center of the photo is Morris Kantrowitz, GPO's technical director in the 1930s and 1940s.
Caption: Two analysts testing paper samples, late 1930s. One of the primary responsibilities of the testing division was to assure that the vast quantities of paper purchased by GPO by competitive bid met standards for composition and quality set by Congress.
Caption: Testing paper in the mid-to-late 1940s.
Caption: Augustus E. Giegengack was an appointee of Franklin D. Roosevelt and served as Public Printer from 1934 to 1948. Mr. Giegengack continued and expanded many of Mr. Carter's reforms, greatly expanded the physical plant, and saw GPO through World War II.
Caption: The testing division produced GPO's ink and press rollers well into the 1990s. Here two workers formulate ink in the 1930s, and another forms a press roller on one of several specially built machines.
Caption: GPO's large auditorium, Harding Hall, could accommodate its entire vast workforce and was in demand for many events during the war years. This dance, which took place in May 1941, raised funds for war bonds.
Caption: GPO was a hub of frenetic activity during World War II and not only on the production floor: Here, women are at work during breaks, sewing for military hospitals.
Caption: This building, covering almost half a city block on the corner of H Street and North Capitol Street, NW, in Washington, D. C., was opened in 1940. With it, the total floor space of the GPO facility grew to 33 acres. It sits on the site of the first GPO, purchased by Congress in 1861, and next to the buildings constructed for GPO in 1903 and expanded in 1922.
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|Author:||Cameron, James T.; Barnum, George D.|
|Date:||Jan 1, 2018|
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