Repoht
or the
NEW ENGLAND ASSOCIATION of CHEMISTRY TEACHERS The Chemistry of Writing Inks' CHARLES A. SCHMITT Carter's Ink Compahy, Cambridge, Massachusetts HEN a person writes with a fountain pen, or a Otto Tachen in 1666, Dr. William Lewis in 1748, and steel pen filled with ink, he is using a method of Ribeaucourt in 1792. August Leonardi of Dresden in transferring thoughts to paper which has been in 1856 patented an iron gall ink with alizarin and indigo as coloring agents. Croc of Paris followed with the existence for many centuries. I t seems probable that the carbon ink of ancient use of aniline dyes in 1861. The State of MassachuEgypt (about 2500 B.c.) was prepared in the form of setts passed a statute in 1899 regarding specifications solid sticks, as in China. Water was added to make a for a standard record ink, using definite amounts of paste and reed pens were used to write on papyrus. tannic and gallic acids with iron sulfate, hydrochloric Inkstands have been found in ancient tombs and rnins, acid, and aniline blue. This formula is similar to that from about 1600 B.c., containing dried carbon. The proposed by Schliittig and Neumann in their book, monk Theophilns, who wrote an encyclopedia of "Die Eisengallustinten." The U. S. Bureau of StandChristian art in the 11th century, described a method ards also has similar specifications for the writing of preparing writing ink from thornwood and mixing i t ink used in all government records. At this point i t with green vitriol (ferrous sulfate). Alhertus Magnus, may be interesting to state that the Declaration of in his writings from 1193 to 1280 A.D., refers to making Independence and the Constitution of the United States an ink from green vitriol. Peter Canneparius, pro- were written with an iron gall ink. Writing inks may be classified according to the fessor of medicine a t Venice in 1660, made black ink from galls and vitriol, and colored inks from various following categories: woods and the juices of berry-bearing plants. On the 1. Blue-black-permanent. Writes blue and oxidizes t o black first page of John Milton's Bible there is entered in his color. Made with tannic-gallic acids, iron sulfate, and aniline blue. own handwriting the record of births of himself and 2. Blue-permanent. Writes blue but does not change its members of his family. One of these dates (his daughoriginal color. ter's) is May 2, 1652. These ink writings appear to he (a) Made with metallic gallotannates and oararosanilin made with iron gall inks. blue. (6) Made with soluble Prussian blue. Writes blue. In the days when writing was a polite accomplishstays blue. Made with ferracyanide group. Soluble ment the commercial manufacture of writing ink was in oxalic acid. not profitable. The careful housewife would rank i t 3. Blue-washable for school and college use where permanent among her duties to make ink from her recipe hook. records are not required for students' work. Water reHere is one copied from an old English family booklet: moves writings. Made with acid and basic blues not fast to water on writing paper. "Take four ounces of gum arabick, beat small, two 4. Black-permanent. Writes black, becomes blacker by age. ounces of gall, beat gross: One ounce of copperas, and Gwd for V-mail letters. a quart of the comings off strong ale. Put all these to(a) Made with gallotannate of iron base with a 3 to 4 gether and stirr them 3 or 4 times a day for about 14 aniline color combination. days, then strein through a cloth." Another recipe ( b ) Made by oxidizing logwood extract (hematoxylin) with chromate of soda t o hematin, producing a says to put a little brandy in theink to "hinder mouldipurple-black color. ness." 5. Black-washable. A popular public school ink, for penIn 1609 Guyot invented an iron gall ink and sold it manship classes. Made with blue and jet shades of nigrosin in Paris. The earliest scientific investigation of the and indulin. 6. Colored inks. I n this class are the permanent and washable chemical reactions between iron salts and an infusion reds, green, violet, and brown. Used in business for bookof galls appears to be that of Robert Boyle of Oxford keeping and contrast work in department offices. These in 1663. Other men to carry on this line of work were inks are made with acid and basic aniline dyes which contain 'Abstract of an address given a t the 226th meeting of the N.E.A.C.T. a t Mechanic Arts High School, Boston, Masachusetts, on May 6. 1944.
7.
organic radicals that are capable of combining with mordants t o fix thecolors on the fiber of the paper. Recording gage pen inks. The use of this class of ink is
tremendous now because of war industrial plants with hundreds of recording instruments. The ink specifications require pure colors and materials, and tests are made for viscosity. speed of penetration, time of drying on charts, and absence of o5sets on crossed-line tracings by the recording pens. 8. Indelible writing inks. Made especially for laundry work, where fastness t o hot water, soap, and bleaching chemicals is required. Alcohol-soluble aniline colors of high purity and strength are used with special distilled coal-tar solvents. The Army and Navy Departments of Laundry Equipment order a t times over 100,000 bottles of these inks for the soldiers and sailors t o mark their underwear, personal belongings subject t o water damage, and various types of cotton and woolen clothing. 9. Drawing inks. Made for draughtsmen and artists in newspaper and photographic work. The black ink is used now largely in the drafting rooms of immense war plants where blueprints are required for hundreds of machine and instrument parts. The ink formulas are the result of hundreds of experiments t o obtain the finest particle size and uniform dispersion of carbon black in certain vehicles miscible with water. All these drawing inks must be waterproof on tracing cloth and paper. The colored inks are made with selected alkali-soluble dyes. 10. Show card and poster inks. Used for theater and stage screen work. Department stores have their own poster artists who make up and color all kinds of displays for their show windows and inside store signs, as sketches of ladies' dresses, coats, hats, etc. Lobby posters for the movie theaters, hotel easel sign cards are drawn and lettered with special pens with these sa-ealled pigment inks. The studios Hollvwood. . . ~-in~ ~ ~ .-esoeciallv ~ . - Walt Disnev, use these colored inks made in many shades for technicolor productian work. I n this class of inks also belong those made with gold and silver bronze, for greeting cards and border lines.on private letter paper. White writing ink is used largely for marking in photographic albums and sketching an dark-colored papers. 11. Hektograph and duplicator writing inks find extensive use in making copies from one master writing on gelatin-coated cloth. Used by large firms for all kinds of order blanks and work sheets. China, before her present war with Japan, bought large quantities of this ink in red and purple colors t o use in making copies of school lessons for children, since it is cheaper than printed paper. 12. Invisible writing ink, Used for secret code letters, especially now in these war days, for all forms of messages. These are written on different parts of the human body, in newspapers, magazines, paper money, postage stamps. and with specially treated chemical paper. These inks are made with chemical salts which develop color by heat, ammonia, or sulfide fumes. Starch and dextrin writings are made legible by iodine vapors.
These 12 classes of writing inks are made from secret formulas and therefore I could mention only in a general way their ingredients or process of manufacture. I can say a little about tannic and gallic acids and +e tannates and gallates. The best-known tannin, gallo-
tannic acid. of formula ClaHynO.. *. .. ., is obtained from Turkish aleppo, Chinese, and Japanese gall nuts. By special extraction methods, the finely ground galls give a tannic acid extract which may be determined gravimetrically or by the Schroeder-Lowenthal titration. Gallic acid, CpHsOs (3,4,5-trihydroxybenzoic acid), is obtained from gallotannic acid by fermentation with mould fungi such as Penicillium glaucum and Aspergillus niger or by the hydrolytic action of dilute acids. Tannic acid reacts with ferrous sulfate to give a brown-black color due to ferrous tannate. Gallic acid gives a blue-black color of ferrous gallate with the same salt. Air oxidation of these compounds gives the principal ingredients of the iron inks. The chemistry of writing inks is knowledge acquired by the ink chemist over a period of many years of research and experience in the manufacture of these inks. Laboratory control of materials and products tested against standards requires scientific knowledge, as millions of bottles are used every day for every purpose of writing. It is not generally known, however, that the ink chemist is called upon to examine the ink writings on questioned documents. Often he will be called upon to testify in court as an expert witness and perform tests on the questioned writings. In fact, he can make an analysis of individual letters in a word. To show vou the scope of chemical tests on ink writinas in disputed docume&, I might list some of the cases in which the ink chemist has played an important role in the courts: 1. Identification of Cochineal red ink writings in a Jewish family Bible 75 yPars old 2. ink writing in a girl's diary which saved her from a prison sentence 3. Purple ink records of a state institution found to be consistent with dates 4. Address on wrapping paper covering a bomb which exploded 5. Signatures On stock cert*cates with a certain hotel ink 6. An extortion letter for $100,000 written with washable blue ink 7. A Sight draft changed from $500 to $500,000 to a nurse 8. A promissory note and confirmatory letter for a million dollars 9. Birth and baptismal certificates in a claim of an heir to a million dollars 10. Bible records to prove claims of heirs to a seventeen-million-dollarestate.
