G. ROSS ROBERTSON University of California, Los Angeles, California
ANEXTREMELY
valuable tool in chemical education and an interesting example of applied organic chemistry are combined in the modern fluid or "spirit" duplicator. Postwar improvements in both mechanical design and in supply materials make available several good outfits for office use. With a t least 300 copies obtainable from a single modern "master" sheet, examination questions may be written for large classes. Even in a small class of 20 the product of a fluid duplicator is much more satisfactory than a set of questions written on a blackboard. I n this writer's department it is now t,he universal custom to spread such questions over two, three, or four sheets of paper, with adequate space allowance after each question. This does not mean regimentation of answers by filling in blanks. The plan does, however, provide a complete document, question and answer, which is very convenient for grading, classroom "postmortem," and office conferences. Special types of question are facilitated by this process. For example, one may easily sketch a thermometer, graduat,ed from -40' to +50°C., shown as partially immersed in a cold liquid. A companion themometer of ordinary type is pictured hanging free in the open air. The question is brief: "What is the true temperature of the cold liquid?" No verbal prompting is required, suggesting the numerical values to be used for stem correction. The student is faced with the problem in the natural manner in which he might meet it in the lahoratory, and has to select his own dats. Numerousotherapplicationsof theduplicatorarealmost obvious. OLD-TIME DUPLICATORS
The fundamental principle of the fluid duplicator is not new, but the essential combination of ideas embodied therein had to wait for fruition long after World War I. A survey of the main types of duplicating processes and machines has been given by Herrmann,' including the fluid or spirit devices. The discovery of methyl violet, and of crystal violet, which is apparently the most intensely-colored substance known to man, led promptly to the "indelible" pencil and t,he quaint copying method of the nineteenth century. For example, the railway station agent of 1890 had a bound book of tissue paper in which he inserted the latest bill of lading, written with a pencil whose "lead" contained methyl or crystal violet. A damp cloth was laid upon the tissue sheet which rested on the bill. The tissue, slightly moistened, picked up I
HERRMANN,I. A., The QBe, April, 1951, p. 9.
enough of the dye to yield a copy legible from the top of the tissue. Next came the "hectograph," in which crystal violet became a component of the coating of a special carbon paper. The purple image on a carbon copy from this source was then transferred to an awkward gelatin pad, which in turn theoretically yielded 100 copies, tediously stripped from the pad. Not until the late 20's did somebody, in what the patent office calls a "flash of genius," devise the scheme of moistening blank paper with an organic solvent of limited solvent power, and then pressing that moistened paper against a hectograph "master sheet" or crystalviolet carbon copy. Obviously the master had to be done in reverse, like the face of a printer's type form. This German invention reached the European market as the "Ormig" machine, and soon attracted commerrial attention in America. Beginning with the "Standard" machine in 1931, American competition appeared not only under the Standard trade name, but also others including Ditto, Rexograph, Old Town, Wright, Wolher, "Copy Duplikopy, Heyer, and Dick (Azograph). With the evception of the new (1953) azo modification all of these machines play the same role. A master sheet of special, smooth white paper receives the typed or hand-drawn image, done in reverse. The machine then lightly moistens a sheet of slightly absorptive blank white copy paper with the properly chosen alcoholir fluid, and immediately presses this paper against the master. This process not only may, but must proceed rapidly, before the alcoholic film can evaporate appreciably. Rapid, efficient copy service is thus availahle, especially from electrically-driven machines.
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DUPLICATOR CARBON PAPER
During the 1930's there were commercially available separate sheets of the dye-loaded carbon paper and of blank master paper, each chosen to give maximum clearness and neatness of letter image. Shortly there came a demand for more copies per master, and the carbons were more heavily loaded with dye. Still more pressing was the complaint of offire women about soiled hands, and it became necemry to ronsolidate master and carbon in one fold-over unit which did not have to be shuffled. Although some special, lightly-inked master carbons are now on the market, this writer has been unable to produce as clean-cut lines on Rnid-duplicator copies as he could in 1938. Blue, green, red, and even black carbon paper are now availahle, but none of these is equal to t,he crystal-violet product.
APRIL, 1955
201
The continued complaint of office workers about soiled should not be used in confined areas such as small offices hands has led to the very recent commercial offering without exhaust ventilation," and recommends "an enof master sheets in which the coating of crystal violet closing hood over the receiving basket." The second disadvantage, if such it can be called, is water-proofed, but, of course, not rendered alcoholproof. Such a master deposits little or no color on moist arises from the fact that methanol is somewhat too good a solvent for crystal violet. Bright, well-inked copies hands, to the satisfaction of the officepeople. are available, but few in number because the master DIAZO PROCESS image wears out prematurely. Only 200 copies might Recently, Klimkowski and Florence2 have reported come from use of methanol with its high hydroxyl their findings in an attack on the soiled-hands problem content, whereas 300 or more could have been obtained from a new quarter. These workers do not use a ready- from a commercial, blended fluid. Manufacturers of the machines furnish proprietary prepared dye in the carbon paper. They incorporate into the paper and fluid the separate organic interme- fluids in which the dye solubility is restricted to an apdiates which, after typing and placement in a machine, propriate level, with lighter, but still acceptable intenfinally get together and synthesize the color stuff as the sity of inking. Although these fluids are somewhat copies are made. The classical aeodye coupling reac- high-priced, it is advisable to employ them unless the tion was chosen for the procedure. The "carbon" coat- users have enough technical familiarity with organic ing, instead of being made of crystal violet and adhe- solvents to make sure that a homemade mixture does sives, contains as principal material the powdered double not contain either nonvolatile, oily impurities, or corsalt of zinc chloride and the relatively stable diazonium rosive acid, and will not evaporate fractionally. Comsalt of p-aminodiethylaniline. From this carbon paper mercial fluids of higher solvent power are sometimes ofa reverse master is typed as usual. Since the diazo- fered as options. Although some fluids have been patnium salt is somewhat acidic, it will not couple in the ented, it is extremely doubtful whether a patent on a mere mixture of well known organic solvents would hold particular reaction to come until an alkali is added. In the duplicator machine, instead of a simple alcohol up in court. Bjorksten4 has reported in detail on the problem of or blend of alcohols, an alcoholic solution of phloroglucinol, or similar phenol or phenols, and diethanolamine blending alcoholic solvents for duplicators. The obis applied to the white copy paper. Contact of the dia- vious suggestion of substituting ethanol, a compound of zonium salt in the typed image with the phenol imme- less water-solvent power, for methanol, proved not to be diately yields the expected azo dye a t the high pH value a simple remedy. Blurring of copy images resulted. assured by the diethanolamine. I n another modifica- Furthermore, federal law does not authorize use of edtion of the process, the diazonium salt is placed in the ucational, tax-free ethanol for such purposes. Common "carbon" coating, while the phenolic coupling agent is denatured alcohol is not acceptable, causing fouling of incorporated in a special copy paper. The fluid con- machines and possible corrosion. Remedies proposed by Bjorksten include the addition tains only alcohols and the pH regulator. Recipes for red and blue colors are given by Klimkowski and Flor- of a nonvolatile alkanol to prevent blurring, and, according to Bjorksten's theory, to "plasticize" the crysence. Apparently the azo process has met considerable favor tal-violet carbon mixture. Where ethanol is available, with those insisting on clean hands. Unfortunately, partial or even complete elimination of the methanol is the limit of 50 copies per master, as contrasted with 300 possible through addition of Methyl Cellosolve, pinacol, or more by the crystal-violet process, is a t present a or 2-methyl-2,4-pentanediol to the ethanol. drawback. Am dyes are not nearly so intensely colored DUPLICATING MACHINES as the triphenylmethane derivatives. I n view of current market uncertainties in this field, DUPLICATOR FLUIDS purchasing agents may note the following - -gratuitous "vice worth: The principal constituent of duplicator fluid has been "Ot pay much to the saksman's synthetic methanol, which alone yields good copies. T~~ disadvantages are noted here: first, toxicity, not numerous "talking points" on nonessentials. The serious if the duplicator workroom is well ventilated, or function of a fluid duplicator is actually very simple, use of the only occasional, Serious headaches and the all-important aim is to do this one operation steadily and uniformly without costly service calls for and illness were reported where one ill-advised office worker operated a machine in a large closet under a stair- adjustment. Such items as metal, glass, or ~ l a s t i c way. McAllister,3an industrial hygienist, in a critical fluid containers, square or round, on top or on the side, analysis of hazards in atmospheric pollution by dup& precision of COPY register, trick valves or paper holders, cators, ends with the flat advice: "spirit duplicators or streamline appearance are minor considerations. (2) The heart and soul of the duplicator lie in the KLIMKOW~KI, R. J., AND R. T. FLORENCE,U. S. Patent mechanism for applying the alcoholic fluid to the copy
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2,634,677 (1953). MCALLISTER,R. G., Am. Ind. Hyg. Assoc. Q w t . , 15, No. 1, 26 (March, 1954).
RJORKSTEN,J., U. S. Patents 2,228,108 (1940), 2,262,488 (1941), and 2,294,711 (1941).
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JOURNAL OF CHEMICAL EDUCATION
(3) If you foresee use of the azo modification with paper. Do not buy a duplicator in which adjustment of this mechanism cannot he done by the office woman its chemically-treated fluid, insist on a machine with after simple training. The mark af a poor duplicator stainless-steel roller for application of the chemically design is seen when copies come through lightly inked reactive material. Brass rollers, in common use, will near one margin anddark near the other,inspite of proper serve for crystal violet hut not for the diazo process. attention to cleanliness of machine by the office worker. (4) Despite the great advance in prices of mechanSome of the best duplicators use cloth wicks to convey ical equipment since the war, regular stock models of fluid to the roller which wets the copy paper directly. fluid duplicator are selling today a t prices not exceeding The most critical scrutiny by the buyer should be di- those of 1939, and often much less. This obvious cut rected toward the position of the wick, and the manner in real price has been accomplished by elimination of in which the fluid is delivered to wick and thence to rol- such luxuries as substantial castings and machined steel ler, so that neither too much nor too little fluid is deliv- gears. The buyer should thus watch out for excessively light, pressed-metal parts in plares where wear is heavy. ered to the entire surface of roller and paper.
