The Topic is Ink

The Topic Is Ink
© Calvet M. Hahn 1981

A series of recent expertizing problems has made it clear that not much is known in philatelic circles, even on the expertizing committees, about writing inks and their dates, applications, and characteristics. Because ink analysis is one of the important methods of determining whether a cover is partially forged or has been tampered with, I have pulled together data on inks for my own expertizing. Some of these may have broader philatelic interest.

Old inks have characteristics that are not readily duplicated. It is difficult, therefore, for fakers to change old covers in such a fashion that it cannot be detected by experts who do have some familiarity with old inks. In looking at a cover that is under analysis, several questions need to be asked. First, is all the ink on the item the same when some should differ, and does some differ when it should be the same? For example, the address and the manuscript portion of the postmark, if any, should be in different but contemporary inks. This would not be the case, normally, if the writer is the postmaster in which case the two inks should match.

Second, do the inks used all have identical characteristics, or is one of the written portions done with ink of different quality or under different conditions? Obviously, as noted above, inks used at the postoffice and those used by the addressor at home should differ but be of generally similar characteristics.

Third, was any portion of the letter or cover written at a substantially different time? Docketing, for example, might date from a considerably later period. However, if the basic writing ink is not correct for the period of the letter than there is likely to be skullduggery a-pen. Such skullduggery is not necessarily designed to completely forge an item, although that does happen. Much more likely is that additions are made to existing covers to enhance their value. A significant date may be incorporated either in the text or docketing. Existing pen work may be ‘enhanced’ to make it more legible. A supplementary marking may be added.

Not too long ago, a well-known, reputable auction house offered a very rare piece of American postal history, of which about five to eight copies were known. It was shipped to me for inspection. The item itself proved to be perfectly genuine, but as the normal method of delivery was by hand, it should not have had an address-most similar examples did not. In this case, someone decided that an address would help the marketing of the piece and proceeded to add one, with no regard to the problems of the inks involved. The result was a sharp devaluation of a good item in the eyes of a serious collector. The auctioneer withdrew the piece from sale.

Not too much has been done in faking stampless covers until quite recently, unless they had good autographic content. Thus, most fakes are recent and the fakers are not familiar with the inks of the periods in question and how they are applied, as well as a number of items that can trip them up.

Before proceeding into the nature of old writing inks, it is useful to note how they were applied, both in terms of writing and blotting instruments. Obviously ballpoint pens were not used in the 19th century and the use of such writing ink is clear evidence of fakery. What may not be recognized are the differences between two of the most important writing instruments-the quill pen and the steel pen. Illustration number 1 shows the difference in writing produced by these instruments.

Note that the steel nibbed pen shows a sharp outer and inner line to the shape of the letter, whereas the same lines in the quill pen writing is almost non-existent because of the comparative softness of the quill. .
The quill pen came first, as any buff of historical movies or TV can tell us. Quill-written letters show shading in the downward strokes and there is an absence of abrasions of indentations even when the writer is a bit heavy handed. Because quills needed to be sharpened or re-cut frequently, a long letter will show differences between the writing at the end and that of the beginning. It is just about impossible to produce certain characteristics of quill writing with a steel pen, and as few of us today know how to write freely with a quill, forgery is detectable if it is tried.

Nibbed quills were invented in 1809, but their use was very rare until after the War of 1812. The development of a nibbed steel pen dates to the initial experimental example of about 1780, and the first ones were on the market about 1803. Thereafter, steel pen patents began pouring out. Nevertheless, steel pens were not in common use until the 1830s.

The early steel pens used in the United States were almost all imports from England where Birmingham specialized in their manufacture. It wasn’t until about 1860 that large-scale manufacture of steel pens began in the United States. The early steel pens lacked flexibility, which shows in the writing coming from them. The reason is that it was not until 1830 that the elongated nib was incorporated into the design.

The next major development in writing instruments is the reservoir pen. The earliest of this type were the stylographic pens, which came in just about the same time that nigrosine ink was commercially available (1870). This early fountain pen version had no nib to leave nib marks. Its writing is of relatively uniform width and the strokes are comparatively broad. Shortly after the initial stylographic pens came the stub-type pen. It was rare in 1875, but grew in popularity until by 1930 about one-third of all pens were of the stub variety. See illustration 2 for a sample of how this writing looked. There is a characteristic reversal of shading from thick to thin and back again.

One of the characteristics of early fountain pens is their failure to deliver ink promptly when first applied to paper. Thus, there are frequently characteristic initial scratch marks, which indicate to an expert the use of an early fountain pen.

Although ballpoint pens were first sold prior to 1935, the first real commercial sales overseas were in 1943, and they should not be found on letters prior to that date. In fact, the use of a ball-point in American writing prior to the end of World War II-and even a few years later-makes a cover suspect. The first domestic American ballpoint sales were at Gimbels’ department store in 1945.

The first ballpoint pens left a coarse structureless line with an abrupt thickness on curves, where the writing changes directions. Ballpoint writing can generally be tampered with fairly easily. About 1952, a new type of ink was introduced for these pens; that ink can identify ballpoints, and writing from pens sold after that date. This difference permits us to tell when a particular ballpoint document was written.


One problem in analyzing ink written on cover stems from the use of blotting paper. While blotting paper dates to 1465 and was used in the 1500s and 1600s, it was not commonly used. Until almost the end of the 19th century the most common practice was to let ink dry naturally in the air. If blotting was to be done, sand was used and can be found imbedded in the inks of such documents. Many covers show the effect of this sand drying either in the cancellation or in the handwriting.

It is a rare cover dating to the period prior to the War of 1812 that would show signs of having been blotted by blotting paper. Such an example would automatically call for expertization if there were any question about authenticity. Sand or air drying were the common methods right on through the prestamp period and up to about the banknote stamp era.
Iron nutgall ink, one of the most common writing inks of the 19th century, shows age discoloration much sooner when blotted than when left unblotted. It will also fade sooner, although it retains a blue color much longer, for most of the darkening agents are removed by the blotting. If the blotter is not applied immediately, only the heavily shaded portion of the writing will show this effect.

A characteristic of blotted ink that is important in expertizing is that such ink remains primarily on the surface rather than being absorbed into the paper.

Carbon Ink

Carbon inks were among the very first used. India ink is among the oldest of these, having been discovered and used about 2000 B.C. Carbon inks are made from charcoal or soot suspended in a gum, glue, or varnish medium. Because much of the best-quality ink was made from lamp black, the color varied from dark brown to blue-black.

During the 19th century, commercial carbon ink preparations were artificially darkened with a blue pigment such as Prussian Blue. The nature of the blue pigment introduced helps date India inks. Although India ink is the oldest ink in general use, it is not widely used as a writing ink. The reason is its thick nature, which is not suited for a reservoir pen. Even nibbed pens of the steel variety will clog up with this ink, unless constantly cleaned.

India and other carbon suspension inks do not penetrate paper. Rather, the layer of ink lays on the surface of the paper bound by a thin film of dried glue, with its color primarily derived from the carbon particles deposited on the surface.
Because the color comes from a layer of carbon, it is highly resistant to chemical bleaches, although it can be removed by scrubbing with a detergent. Not all the carbon particles, of course, can be eliminated, and attempts to remove carbon inks can therefore be detected by experts.

There has been a change in the composition of carbon inks over the years. Modern carbon inks are made with carbon black, not soot, and the binder is no longer hide glue but shellac in a borax solution, to which ammonia is added to promote flow. Because of the alkaline nature of carbon ink, it spreads beyond the nib marks when applied by nibbed pens.

Forgers tend to forget that carbon inks are basic in nature and therefore cannot be mixed with the acidic iron-tannin inks to darken them. Such a mixture would cause the suspended carbon to coagulate, leaving a muddy mixture.
The dating of carbon inks is primarily done by focusing on the binder and the blue toner added. Any binder, other than hide glue, indicates modern ink, particularly if there is borate present. In addition, synthetic blue agents that did not exist in the classic stamp period are used as colorants so that their presence on purportedly old covers indicates tampering.

Iron-nutgall Ink

Iron tannin inks basically replaced carbon inks in the Middle Ages as the general writing ink fluid because they were easier to handle. The large-scale use of these inks arose almost simultaneously with the introduction of paper in Western Europe . Initially, the tannin from hides was used, but it became apparent that nutgalls would serve as well so that most colonial documents use nutgall ink. There were other inks used in the colonial period, particularly during the American Revolution when improvision was the byword. These are frequently less durable and present problems in washing or cleaning covers, which the true iron nutgall inks do not. A typical and famous example is the lovely bayberry ink used at Albany, N.Y., which gives a magenta color.

The basic problem with nutgall ink is that it tales time to darken. Thus, freshly prepared inks were barely readable, an unsatisfactory situation for a writing fluid. When the ink was allowed to appropriately darken by maturing it in a vat, it was found that a large portion of the compound precipitated, creating a sludge that would clog pens. A number of items were added to prevent such precipitation and it was eventually discovered that the addition of gum Arabic hindered the formation of a precipitate although it did not prevent it. Thus, gum Arabic became a standard component of old iron nutgall inks. It gave the violet black inks a glossy look that is characteristic.

Another early change occurred when it was discovered that tannin from the tanning industry did not give the best inks, and nutgall tannin was substituted wherever possible. Nevertheless, some hide inks continued to be produced, particularly in rural areas where nutgalls were unavailable. The new nutgall inks were a combination of a solution of five percent tannin with suspension of iron salts (green vitriol) buffered with gum Arabic. The insoluble particles of blue-black ferrosoferric gallate rested on the surface of the paper while the ferrous gallate solution penetrated the paper, oxidized, and served as a mordant to create a permanent dark color.

Many of the inks produced in this fashion were quite acidic and eat into the paper as can be seen in a number of old letters. All were acidic and thus not beneficial to the paper, but some were greatly so. In 1834, a major change in iron nutgall ink technology occurred. The English firm of Stephens developed a new writing fluid that was not a part suspension but a solution. This was the first ‘blue-black’ writing fluid and quickly became one of the favorite inks around the world. What Stephens did was to add to his ink a small portion of indigo, and probably also some logwood. While this use of indigo had been suggested as early as 1785, Stephens was the first to do it commercially. The indigo changed the characteristic initial violet-black into a blue-black. Of course, over time (two to three years), all these inks turned into a permanent black.

The use of a Stephens type ink on a document dated before 1834 is a sure sign of forgery. This ink was not introduced in America, in all probability, for several years after that date. Through the years more and more bluing ingredients were added to these inks to create a darker initial color. Thus they took longer to turn black. Once the new coal tar dyes were commercially available for ink, they were used a colorants, so it is possible to differentiate the blue-black inks of the post 1860s from those used before, a significant point in philatelic analysis.

The next big change occurred with the study of iron gall inks by the German government in 1870. Published about 1890, the study set new formulation standards for iron gall inks, which were those subsequently used throughout the world.

Logwood Ink

Logwood also yielded tannin, and at one time logwood inks were among the most popular in use. The popularity began after Runge discovered what became known as chrome inks , which were put on the commercial market in 1848. Some of the early violet inks came from logwood. The best logwood inks were an intense blue black. They were noncorrosive and flowed freely. Once dry, they could be wetted without smearing or spreading.

Commercially, logwood inks were produced with copper or iron sulphate, with the former preferred but the latter most used. These inks used less logwood and thus were cheaper. They were acidified and thus could corrode pens. For many years such logwood inks were the standard copying ink.

Visually, matured logwood and iron gall inks look the same. However, they can be readily identified and separated by use of a 5% hydrochloric acid solution. With this, iron nutgall ink gives an immediate blue or blue green reaction while logwood yields a red or purple red color. A pipette with only a very small amount of acid can be used so that only a tiny portion of the paper is affected, or a flake of ink can be scraped away and tested.

In expertizing inks, it is necessary to recognize that logwood inks have peculiar flow that looks unlike other inks. Illustration number 3 shows how logwood ink flows back over itself when a second stroke crosses a first one. Thus at areas of shading, or where a stroke angles, there can be a flowback of the ink into other portions of the line so that it gives the appearance of retouching although it is not.

Blue Ink

Blue inks were potentially possible for many years before writing inks of that color appeared on the market. Prussian blue was discovered in the 1700s and indigo even earlier. However, blue writing inks show up on American letters in the 1830s, probably not much before 1838, from which I have seen several examples. By 1839-1841, they are common, having been used by postal officials at many offices.

These blues are acid inks. For example, Prussian blue is mixed eight parts to one part oxalic acid and dissolved in water. The first blues are not particularly water-soluble today. That is, the paper can be washed without having the ink run. However, about 1845 a less water-resistant writing ink was introduced and it will run if wetted today. About this same time, the first running cancellation inks appeared in handstamps. There is a very dark blue canceling ink used at Hartford, CT, which will run, and in Texas several locally made colored inks were used that also are water soluble. Other than these few, however, I have been unable to record any cancellation ink that was in use during the prestamp period (that is, up to 1856) that runs. This is important for those seeking to authenticate old markings ,for cancellation inks that show signs of running when they should not are modern fakes.

Among the early blue writing inks, the Prussian blue inks can be identified because they are readily affected by the use of ink eradicator while the other blues are not. Many blue inks introduced in the late 19th century and early 20th century are also affected, but the methylene blues found today are generally not readily affected.

Methylene blue cane into use as a writing ink not before 1887. This is almost a decade after Baeyer discovered artificial indigo (1878), which quickly replaced natural indigo as a dye colorant in writing inks. It is also well after the first of the alizarin blue inks were created in 1877. Because of the marked changes in the blue coloring used in writing fluids that began in the last quarter of the 19th century, it is possible to distinguish letters written by the earlier fluids, and when a letter is written in the later colorant know that it is a forgery. By the turn of the 20th century, the Prussian blue writing ink had already dropped out of use.

Nigrosine Ink

The next major development in blue-black inks was the introduction of nigrosine ink, a coal tar die derivative. This ink is a stain obtained by dissolving nigrosine in water to create a suspension rather than a solution. Many nigrosine inks (both black and blue) can be identified by microscopic examination, for the lines have dark outer edges, like a black border, in addition to a peculiar metallic luster. (See illustration 4). This dark edge is different in character from the nib edge found with earlier inks. Of course, these inks also react differently under black or ultraviolet light than do the earlier iron nutgall inks.

Nigrosine ink was first produced commercially in 1867, and its use in letters purported to be of an earlier date than that is a sure sign of fakery. In fact, nigrosine inks should not really be found on letters prior to the 1869 issue adhesives. The nearly black color (actually a very dark lilac that does not change or oxidize over time, although it may dim through exposure to light) produced when the ink is first used was one of its key selling points. Other advantages are that it flows freely and does not corrode the pen. However, it never does reach the same deep black shade of a good iron nutgall ink and has the major disadvantage in being easily affected by wetting-it runs freely if dampened, one test that can be used in philatelic expertizing. Ink eradicators also easily affect it. Thus, it never received the popularity among businesses that it did among private citizens, another distinction that helps in expertizing.

The last quarter of the 19th century saw the introduction of a number of other synthetic ink colorants. Among these were the reddish eosines (1874), the sulphide inks (1873) such as sulphaniline black, the alizarin group (1868), which includes artificial madder, alizarin blue (1877), and the anilines. The earliest of the anilines was a mauve color discovered in 1856, but apparently not used for a number of years philatelically. The Hussey post was an early user of the handstamp inks, and he uses this color in late 1868. He appears to be using a synthetic blue ink by 1872. The change in colorants had a definite effect upon the writing inks and 20th century inks can be differentiated from those used on letters in the classic period. The change is already noticeable by the turn of the century. A survey of mail made at that time shows the following proportions:

Ink Type Business Personal
Nutgall 83% 30%
Logwood 10% 45%
Nigrosine 7% 25%
Total 100% 100%

The logwood proportion continued to decline through the ensuing years, but there was also some falloff in nigrosine inks. In the nutgall inks, the new artificial dyestuffs such as indigo make the 20th century nutgalls (Carter’s writing fluid, for example) quite different from their predecessors. Another change in ink technology has given us the quick dry inks. The suggestion that an alkaline ink with potassium carbonate might serve as the basis for a quick-drying ink was made as early as 1912, but the first patent dates to 1927, with commercial production probably a few years later. The early quick-dry inks used an azo dyestuff for colorant. A new version, the ‘Superchromes’ was given a patent in 1949. These inks, which are found today, contain copper or vanadium compounds and probably were not in commercial production before about 1954. They resemble the dyestuff inks and do not undergo oxidation reactions. Obviously, no quick-dry or ‘Superchrome’ ink should be found used on a purported classic piece of postal history.

Ballpoint Ink

As noted earlier ballpoint pens were first sold domestically at Gimbels in 1945. They used an ink based on olein, which is still being used by some of the cheaper ballpoints today. These oil-based inks ‘strike’ through the paper as can be seen from illustration number 5a and b from 1947. This is because of the oily nature of the inks. An improvement came in 1955, when a polyethylene glycol type of ink was introduced. This was a much better product. The olein inks can be made to run readily through the use of a petroleum ether test, while the glycols are relatively resistant. This makes it possible to differentiate fairly easily between these two products. Such differentiation may be important to collectors of contemporary postal history but are outside the scope of this study.

Most of the ballpoint inks contain at least 15% dyestuff in order to give them color. More recent formulations contain multiple dyestuffs rather than single colorants, and this also helps to differentiate them. In January 1955, a liquid led ballpoint ‘pencil’ was introduced. The following year a newer version that permitted shading came on the market. While such ‘pencils’ show little difference from ordinary graphite pencil writing of the classic era when only casual inspection is given, there is a marked difference under high magnification,. This difference can be useful when someone has added ‘pencil’ notations in liquid led writing onto older covers that supposedly were written prior to 1955.
5a. Top shows early ballpoint writing, The bottom shows the back of the sheet.
5b shows thickening caused by a change of direction of the ball rotation. Bottom shows typical thicknesses due to irregular ink flow.

Ink in Expertization

Covers were first faked back in the 1850s. However, the real wave of cover fakery is far more modern. There was a major wave of faking about 1890 and again about World War I, but because covers were not collected to the same extent they are today the incentive to fake them was far lower. The major periods of fakery that normally have to be watched are the mid-1930s, the late 1940s and early 1950s (during which a sophisticated group of fakes was produced), and today.
While the earliest fakes are more dangerous simply because they have been around so long and some have become accepted, they can be detected because of the use of the wrong inks just as readily as the more modern fakes. The change in both inks and writing instruments that took place after the early classic period of postal history give us ready clues to pick out bad material. It is for this reason that it seems so incredible that the late 1940s fakes passed for as long as they did.

Fakery is again on the rise, spurred by the huge price increase for classic postal history of the late 1970s and early 1980s. At the moment there are millions of dollars of fake grills, fancy cancels, and covers being readied for market to unsuspecting collectors . Organized crime has also entered the field, so knowing what you are buying and from whom becomes increasingly important.

While it is probably that most of the stampless fakes that will be coming out in the future will use genuine ‘courtesy’ carried covers with added markings (usually applied with out of period inks or markings), these are not available for those wishing to fake many classic stamped covers. Thurs, they have to create covers from scratch from old papers and this means faking writing inks. For this reason it is important to know inks and their dates of use.

Since the modern inks are almost entirely made with synthetic components-a notable difference from the inks used originally in the classic pre-1870 period-the dates and changes notes here can clue you as to what to examine. It is not widely known that the government maintains an ink bank in the Treasury Department, which is available to the Internal Revenue Service and other authorities, and which contains almost every ink manufactured since 1922. Since most forging of philatelic material was done after this date, insofar as classic covers are concerned, the existence of such a resource can be helpful in ascertaining whether an ink is modern.

An expertizing problem arises when the faker has added something to a genuine cover. Frequently pen marks are used to aid in this process and to tie added stamps to the cover. A number of points can indicate when something is not quite right. For example, when something has been erased and new words written over, it is not unusual for the new ink to ‘feather’ as can be seen in illustration 6. This occurs because the paper has been rendered more porous through abrasion. Further, the new ink may be somewhat duller in color.

Forgers who recognize this problem-and so far only a few do-attempt to smooth down the paper first and even perhaps to restore it by the use of sizing material used to fill the pores. These techniques help, but microscopic examination will normally reveal the change. Old letters were frequently folded, and the fold may be just in a place where the forger needs to write. There is a difference in the way an ink looks when it is written over a fold from what it appears when the fold is made after ink has been applied, as seen in illustration 7. If the ink has left a film on the surface, and the paper is afterwards folded, there is an obvious break in the ink like as at the bottom of this illustration.

Figure 7. Top ink line over a fold.
Figure 8. Nigrosine ink with ‘y’ written Bottom fold is over an ink line over the ‘B’, which was written first.

When the ink is written over a fold, there is a slight widening of the ink line, both when the fold is convex and when it is concave. It is easier to see on the convex side as well as when the ink is more fluid. The higher fluidity of modern writing inks used on old documents make this more obvious. If the fold has not been completely broken, it may take some time for the ink to oxidize (in the case of nutgall inks) and make the overwriting obvious.

It is a widespread myth that it is easy to tell which ink line was written first when two ink lines intersect. Usually this only applies when the ink is relatively fresh, not when the overwriting is years later as in the case of many forgeries.
There are clues if the two inks have different characters.

For example, illustration 8 shows a nigrosine characteristic that is not typical of earlier inks in that there is a deposit at the edge of the ink line. This is not the same as the track of a nibbed pen. Another observable characteristic is a flowback that will occur if two inks were contemporaneous and wet when written. This will not be found when the first ink is old and dried. However, the fact that a flowback is not found is not conclusive evidence, for there are many reasons why this should occur.

Frequently the faker has to ‘retouch’ his work. Genuine retouching may have been done to correct an obvious defect when the writing was first done or to add a necessary part, but unnecessary concealed or very delicate retouching is suspect. Honest retouching normally is clear and made with fairly bold strokes. Illustration 9 shows a suspect retouch, which can be compared with the genuine type in illustration 10.
Ink Dating Sequence

Colonial Quill pen; India ink; Black/brown iron nutgall ink
1809 Nibbed quill
1812-15 Blotters come into some use
1830 Imported steel pens
1834 Blue black nutgall ink introduced commercially (Stephens)
1838 Blue writing ink
1845 Soluble blue ink
1848 Logwood ink
1856 Discovery of mauve analine dye
1860 U. S. steel pen manufacturer
1867 Nigrosine inks discovered
1868 Hussey uses mauve ink handstamps
1869-70 Probably 1st commercial nigrosine ink in U.S.
1872 Hussey uses synthetic blue handstamp ink
1875 Stub pens
1877 Alizarin blue discovered
1878 Artificial indigo begins to replace natural
1870s Stylographic pen
1884 Waterman fountain pen
1887 Methylene blue writing ink begins
1900 Prussian blue inks no longer used
1922 Treasury creates ink bank from here on
1927-30 Azo quick-dry inks
1943 Olein ink used in ballpoint pen
1945 Gimbels sells ballpoint pens
1954 Superchrome quick-dry ink
1955 Liquid lead pencil; polyethylene glycol ballpoint ink

Colonial ’round hand’ writing of the mid-1700s.

Example of the earliest use of Spencerian handwriting. This was Mr. Spencer’s letter to his wife announcing he was going to publish a book on handwriting. It is dated July 1845 so no earlier examples not in his handwriting should exist. Popular in 1860s.

The popular American Palmer method of handwriting taught by A. N. Palmer that replaced Spencerian.


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