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How To Study Forged And Disputed Signatures

Forgery As A Profession

How To Determine Age Of Any Writing

The inks in common use over the United States at the present time,

and for some years past, are not as numerous as one might be led

to conclude. They are probably fifteen or at most twenty in all,

including the most popular blue, red, magenta, and green inks. But

among these there is a notable difference in character. Some are

thick, heavy, and glossy, in character, and flow sluggishly from the

pen. Few of these become much darker by standing. In this class will

be found the copying inks and those in which a large quantity of gums

or similar thickening agents are used.

Other inks are pale, limpid, and flow easily from the pen, and this

class usually shows a notable darkening by exposure to sunlight and

air. It will be unnecessary here to refer more particularly to the

intermediate varieties or to discuss their various composition.

It should be, remembered here that in the last twenty years, or since

the introduction into general commerce of aniline colors, which

Hofmann discovered in 1856, these latter have been employed more and

more in writing fluids; not only in mixtures of which they are the

principal ingredients, but to a greater or less degree in all inks.

Their presence, even in small quantity, in the gallo-tannate of iron

and logwood inks can be generally detected by an iridescent and

semi-metallic luster.

To assist in determining the ages of writings by one and the same ink,

it is to be observed that the older the writing the less soluble it is

in dilute ammonia. If the writing be lightly touched with a brush

dipped in ten-per-cent ammonia, the later writing will always give up

more or less soluble matter to the ammonia before the earlier. In case

of inks of different kinds this test is not serviceable, for

characters written in logwood ink, for instance, will always give up

their soluble material sooner than nutgall inks, even if the last

named be later applied. To estimate the age of writing from the amount

of bleaching in a given time by hydrochloric or oxalic acid is very

precarious, because the thickness of the ink film in a written

character is not always the same, and the acid bleaches the thinner

layer sooner than the thicker.

The determination of the age of a written paper is a problem difficult

of solution. According to F. Carre the age can be approximately

determined if the characters written in iron ink are pressed in a

copying press and a commercial hydrochloric acid diluted with eleven

parts of water is substituted for water; or, if the written characters

are treated for some time with this diluted acid.

The explanation is that the ink changes in time, its organic substance

disappears little by little, and leaves behind an iron compound, which

in part is not attacked even by acids.

An unsized paper is impregnated with the described diluted acid,

copied with the press, and a copy from writing eight or ten years old

can be obtained as easily as one by means of water from a writing one

day old.

A writing thirty years old gives, by this method, a copy hardly

legible, and one over sixty years old, a copy hardly visible. In order

to protect the paper against the action of the acid, it should be

drawn through ammoniacal water.

To determine the exact age of writings by the ink is not easy. The

approximate age may be determined with some degree of certainty. If

ink-writings are but a few days old, it is easy to distinguish them

from other writing years old. But to tell by the ink which of two

writings is the older, when one is but two months and the other two

years, is, as a rule, impossible.

Where during the progress of a trial a document purporting to be years

old is introduced in evidence, and it can be shown that it is but a

few days old, having been prepared for the occasion, ordinarily the

age of the writing will be comparatively easy of demonstration by the

expert. Oxidization will not have set in to any extent, if the ink is

very fresh, and this, with a careful watching of the color for any

darkening, will determine whether or not the ink is fresh. This ink

study should be a question of the utmost interest to bankers and bank


A ten-per-cent solution of ammonia applied to two inks in question

will show which is the fresher. The older ink will resist the action

of the ammonia longer and give up less soluble matter than the newer

writing. Nutgall, and logwood inks, of course, should not be tested

comparatively by this method, as the logwood ink will respond to the

ammonia sooner than the nutgall ink.

F. Carre also gives another method for determining, approximately, the

age of ink-writings. If the writing is in iron ink, and is moistened

with a solution of one part of hydrochloric acid to eleven parts of

water and put in letter-copying press and copy transferred to copy

paper it should give a strong copy, if but ten years old; a hardly

legible copy, if thirty years old; and if sixty years old, a few marks

will be copied, but they will not be legible.

If the same solution be used in place of water, as in the ordinary

letter-copying process and the copying paper be saturated with it, the

result will be the same.

To determine the age of writing by applying bleaching acids and

watching results and counting the seconds is a dangerous method. Thick

inks will respond to the acids slower than thin, and the time

comparisons are misleading.

Safety inks, so-called, designed to resist the action of acids and

alkalies have been repeatedly put upon the market, but no such ink has

ever successfully challenged the world and proved its title of safety.

Many chemicals are recommended as restorations for faded writing, but

these should be avoided as far as possible, as they are liable to

stain, disfigure the paper, and in the end make matters materially

worse. Familiarity with particular handwritings after some practice

will enable the reader to make out otherwise unintelligible words

without any other assistant than a powerful magnifying glass.

If the ink is very faint, the simplest and most harmless restorative

is sulphate of ammonia, but its loathsome smell once encountered is

not easily forgotten. The experiment in consequence is very seldom

repeated for the result is scarcely good enough to risk a repetition

of so horrible a smell.

The writing on old and faded documents may be restored, by chemical

treatment, turning the iron salt still remaining into ferrous sulphate.

A process which will restore the writing temporarily is as follows: A

box four or five inches deep and long and broad enough to hold the

document, with a glass, is needed. A net of fine white silk or cotton

threads is stretched across the box at about one half the depth. Two

saucers containing yellow ammonium hydrosulphide are placed in the

bottom of the box. By means of a clean sponge or brush, moisten the

paper with distilled water; then place it on the net with the writing

side down. The action of the vapor of the ammonium hydrosulphide will

cause the obliterated writing to slowly turn brown, then black. But

within a short time after removal from the box the writing will again


Another method is to wash the document carefully in a solution of

hydrochloric acid, one part, and distilled water, one hundred parts.

Dry the moistened paper somewhat, leaving it just moist enough to hold

a uniform layer of fine yellow prussiate of potash. A plate of glass

with a light pressure should be placed on this. In a few hours dry the

paper thoroughly, and carefully brush off the yellow prussiate of

potash. The writing should come out a Prussian blue. This restored

writing will be permanent unless exposed too much to the light.

The hydrochloric acid must be thoroughly removed; otherwise, it will

destroy the paper. Crystallized soda, two parts, and distilled water,

one hundred parts, in solution, will counteract the hydrochloric acid,

if the document is allowed to float on it for twenty-four hours.



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