Study of Ink, Part 2

[This is taken from David N. Carvalho's Forty Centuries of Ink, originally published in 1904.]


DR. JAMES STARK, a famous chemist, submitted the results of twenty-three years of investigations of writing inks in a paper read by him in 1855 before the Society of Arts, in Edinburg, Scotland. The following is the abstract as printed by the London Artisan at the time:

“The author stated that in 1842 he commenced a series of experiments on writing inks, and up to this date (1855), had manufactured 229 different inks, and had tested the durability of writings made with these on all kinds of paper. As the result of his experiments be showed that the browning and fading of inks resulted from many causes, but in ordinary inks chiefly from the iron becoming peroxygenated and separating as a heavy precipitate. Many inks, therefore, when fresh made, yielded durable writings; but when the ink became old, the tanno-gallate of iron separated, and the durability of the ink was destroyed. From a numerous set of experiments the author showed that no salt of iron and no precipitate of iron equalled the common sulphate of iron—that is, the commercial copperas—for the purpose of ink-making; and that even the addition of any persalt, such as the nitrate or chloride of iron, though it improved the present color of the ink, deteriorated its durability. The author failed to procure a persistent black ink from manganese, or other metal or metallic salt. The author exhibited a series of eighteen inks which had either been made with metallic iron or with which metallic iron had been immersed, and directed attention to the fact that though the depth and body of color seemed to be deepened, yet in every case the durability of writings made with such inks was so impaired that they became brown and faded in a few months.  The most permanent ordinary inks were shown to be composed of the best blue gall nuts with copperas and gum, and the proportions found on experiment to yield the most persistent black were six parts of best blue galls to four parts of copperas.

Writings made with such an ink stood exposure to sun and air for twelve months without exhibiting any change of color, while those made with inks of every other proportion or composition had more or less of their color discharged when similarly tested. This ink, therefore, if kept from moulding and from depositing its tanno-gallate of iron, would afford writings perfectly durable. It was shown that no gall and logwood ink was equal to the pure gall ink in so far as durability in the writings was concerned. All such inks were exhibited which, though durable before the addition of logwood, faded rapidly after logwood was added to them. Sugar was shown to have an especially hurtful action on the durability of inks containing logwood— indeed, on all inks. Many other plain inks were exhibited, and their properties described as gallo-sumach ink, myrabolams ink, Runge’s ink, inks in which the tanno-gallate of iron was kept in solution by nitric, muriatic, sulphuric, and other acids, or by oxalate of potash, chloride of lime, etc. The myrabolams was recommended as an ink of some promise for durability, and as the cheapest ink it was possible to manufacture. All ordinary inks, however, were shown to have certain drawbacks, and the author endeavored to ascertain by experiment whether other dark substances could be added to inks to impart greater durability to writings made with them, and at the same time prevent those chemical changes which were the cause of ordinary inks fading. After experimenting with various substances, and among others with Prussian blue and indigo dissolved in various ways, he found the sulphate of indigo to fulfil all the required conditions and, when added in the proper proportion to a tanno-gallate of iron ink, it yielded an ink which is agreeable to write with, which flows freely from the pen and does not clog it; which never moulds, which, when it dries on the paper, becomes of an intense pure black, and which does not fade or change its color however long kept. The author pointed out the proper proportions for securing those properties, and showed that the smallest quantity of the sulphate of indigo which could be used for this purpose was eight ounces for every gallon of ink. The author stated that the ink he preferred for his own use was composed of twelve ounces of gall, eight ounces of sulphate of indigo, eight ounces of copperas, a few cloves, and four or six ounces of gum arabic, for a gallon of ink.  It was shown that immersing iron wire or filings in these inks destroyed ordinary inks. He therefore recommended that all legal deeds or documents should be written with quill pens, as the contact of steel invariably destroys more or less the durability of every ink. The author concluded his paper with a few remarks on copying inks and indelible inks, showing that a good copying ink has yet to be sought for, and that indelible inks, which will resist the pencilings and washings of the chemist and the forger, need never be looked for.”

Professor Leonhardi, of Dresden, who had given much attention to the subject of inks, introduced in 1855 what he termed a NEW ink, and named it “alizarine ink,” alizarin being a product obtained from the madder root, which he employed for “added” color in a tanno-gallate of iron solution. It possessed some merit due to its fluidity, and for a time was quite popular, but gradually gave place to the so-called chemical writing fluids; it is now obsolete.

Champour and Malepeyre, Paris, 1856, issued a joint manual, “Fabrication des Encres,” devoted almost exclusively to the manufacture of inks and compiles many old “gall” and other ink formulas.

In 1856 Dr. Chilton of New York City published the results of ink experiments which he had made.  The accompanying extracts are taken from the local press of the month of April of that year:

“Some ingenious experiments to test the durability of writing inks have recently been made by Dr. Chilton, of New York City. He exposed a manuscript written with four different inks of the principal makers, of this and other countries, to the constant action of the weather upon the roof of his laboratory. After an exposure of over five months, the paper shows the different kind of writing in various shades of color. The English sample, Blackwood’s, well known and popular from the neat and convenient way that it is prepared for this market, was quite indistinct.

“The American samples, David’s, Harrison’s and Maynard’s are better. The first appears to retain its original shade very neatly; the two last are paler. This test shows conclusively the durability of ink; and while, for many purposes, school and the like, an ink that will stand undefaced a year or so, is all that is necessary, yet there is hardly a bottle of ink sold, some of which may not be used in the signature or execution of papers that may be important to be legible fifty or one hundred years hence.

“For state and county offices, probate records, etc., it is of vital importance that the records should be legible centuries hence. We believe that some of the early manuscripts of New England are brighter than some town and church records of this century.

“In Europe at the present time, great care is taken by the different governments in the preparation of permanent ink—some of them even compounding their own, according to the most approved and expensive formulas.

“Manuscripts of the eleventh and twelfth centuries now in the state paper office of Great Britain, are apparently as bright as when first written; while those of the last two hundred years are more or less illegible, and some of them entirely obliterated.”

While the information sought to be conveyed in the last statement may be in some respects correct, it must be remembered that most of the MSS. extant dating before the thirteenth century were written in “Indian” ink, while the great majority of those of the last two hundred years were not; and this fact alone would account to some extent for the differences mentioned.

The German (Prussian) government in 1859, as the result of an investigation, employed what they termed “Official Ink of the First Class,” i. e., a straight tanno-gallate of iron ink without added color; and if permanence were required as against removal by chemicals, it was accomplished by writing on paper saturated with chromates and ultramarine.

In 1871 Professor Wattenbach of Germany published a treatise entitled “Archives during the Middle Ages,” which has some valuable references to the color phenomena of inks.

William Inglis Clark in 1879 submitted to the Edinburgh University a thesis entitled “An Attempt to Place the Manufacture of Ink on a Scientific Basis,” and which very justly received the commendation of the University authorities. His researches and rational deductions are of the greatest possible value judged from a scientific standpoint. The introduction of blue-black ink is a phase of the development towards modern methods which he discusses at much length.

The object of adding a dye in moderation, he asserts, is to give temporary color to the ink and where indigo-paste is used, it has been assumed that it kept the iron gallo-tannate in solution, whereas any virtue of this kind which indigo-paste possesses is more likely due to the sulphuric acid which it contains than to the indigo itself. The essential part of the paste required is the sulpho-indigodate of sodium, now commonly called indigo-carmine. He further remarks that the stability of an ink precipitate depends upon the amount of iron which it contains and which on no account should be less than eight per cent; he adds rightly, if gallic acid be preferably used in substitution for tannin, “no precipitate is obtained under precisely similar conditions.” This point followed up explains in a measure why a gall infusion prepared with hot water is not suitable for a blue-black, while a cold water infusion is. In the latter case a comparatively small percentage of tannin is extracted from the galls, while much is extracted with hot water and the consequence is, on adding the indigo blue the color is not brought out as it should be. Substantially the same thing occurs with ink made with the respective acids, although the blue color remains for a time unimpaired in the tannin ink, apparently due to the fact that ferrous-tannate reduces indigo blue to indigo white, a change which the low reducing power of ferrous-gallate does little to effect. The vegetable matter in common inks facilitates the destruction, or rather alteration and precipitation of the indigo, for the dye appears in the iron precipitate and may be extracted from it with boiling water.

Dr. Clark’s investigations seek to demonstrate the superiority of tannin and gallic acid over infusions of the natural galls, and he undertakes to determine the correct ratio of tannin and sulphate of iron to be used as ink. His experiments in this line show that:

1.   The amount of precipitate increases as the proportion of iron to tannin is increased.

2.   The composition of the precipitate is so valuable as to preclude the possibility of its being a definite body. Increase of iron in the solution has not at first any effect on the composition of the precipitate, but afterwards iron is found in it in greater but not proportional amount.

3.   At one point the proportions of iron in the precipitate and in solution are the same, and this is at between 6 and 10 parts of iron to 100 parts of tannin.

4.   The proportion of iron in the precipitate varies greatly with the length of time the ink has been exposed.  At first the precipitate contains 10 per cent of iron, but by and by a new one having only 7.5 per cent is formed, and in from forty to seventy days we find one of 5.7 per cent. Simultaneously iron increases in the ink (proportionate to the tannin).

5.   The results show, and practice confirms, that 16 parts of iron (80 ferrous sulphate) and 100 parts of tannin are best for ink manufacture.


The research now travelled in a direction which accumulating experience showed to be obligatory.  Blue-black tannin ink lost color, and the reducing nature of the tannin tended to the formation of a highly objectionable precipitate in the ink, which made writing anything but a pleasure. These two faults were doubtless linked together in some way and seemed not to exist when gallic acid was used, for ink so made was found to precipitate only after a long exposure, it required no free acid to keep the precipitate in solution, and retained the indigo blue color for a long time; alkalis did not decompose the ink, and provided blacker and more permanent writing.  Determination of the correct proportions of gallic acid and ferrous-sulphate was the subject of prolonged experiments conducted on similar lines to those already detailed. The conclusions as to precipitation were also similar. Thirty parts of iron (150 of ferrous-sulphate) and 100 parts of gallic acid were found to be the most suitable proportions for ink-making. It is advisable, however, not to discard tannin altogether, owing to the slow blackening of the gallic acid ink, and a little tannin gives initial blackening and body, while it is absolutely necessary for copying ink.  Initial blackness can also be ensured by oxidizing 21 per cent of the ferrous-sulphate without adding the extra acid necessary to the formation of a ferric salt.

The concluding portion of his research is devoted to the influence of sugar upon the permanence of ink, and the results of the experiments are summed up in the following sentences: “It would be injurious to add 3 per cent of sugar to a tan in ink, while from 4 to 10 per cent would be quite allowable. Most copying inks contain about 3.5 per cent of sugar— not far from the critical amount. With gallic acid more than 3 per cent of sugar hardly varies the precipitate, but the importance of this point is somewhat diminished by the fact that the presence of sugar is by no means necessary in a writing ink. Dextrin is a much superior substance to use. Curiously this body rapidly precipitates a tannin ink; hence it is useless for copying ink, but for the gallic ink it is an excellent thickener.”

Chen-Ki-Souen, “Lencre de China,” by Maurice Jametel, appeared in Paris in 1882, but as the title indicates, it is the old “Indian” or Chinese ink that is discussed.

Schluttig and Neumann in 1890 issued their Edition Dresden on the subject of “Iron and Gall inks.” In this valuable work is to be found the formula which has been generally adopted as the standard where one is used for tanno-gallate of iron ink.

The investigations of other scientific men like Lepowitz, Booth, Desormeaux, Chevreuse, Irvine, Traille, Bottger, Riffault, Precht, Nicholes, Runge, Gobert, Penny, Arnold, Thomson (Lord Kelvin), Davids, Kindt, Ure, Wislar and many more who have dealt with the chemistry of inks, present to us some testimony during a considerable portion of the nineteenth century of the efforts made to secure a good ink.


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