PEN INK AND PAPER CHEMISTRY 1

Pen ink and Paper Chemistry:

How the chemical breakdown of both paper and ink are incorporated into forgeries

and its scientific methods

Dominique McCoy

East Tennessee State University

PEN INK AND PAPER CHEMISTRY 2

Abstract

PEN INK AND PAPER CHEMISTRY 3

Pen ink and Paper Chemistry:

How the chemical breakdown of both paper and ink are incorporated into forgeries

and its scientific methods

Ink analysis is frequently requested in forensic cases involving questioned documents.

Ink analysis usually involves the comparison of a questioned ink sample from a document with a

known ink from the suspect. In more difficult cases, the ability to determine the manufacturer

can be used as a lead in the case. Forensic document examiners follow the standard of visual

examinations by inspecting the questioned document with visible light where the band filters can

be observed under both Ultraviolet and Infrared radiation sources. The second part of pen

analysis is the actual scientific method used to identify the chemical components of the pen ink.

The most common scientific methods are thin layer chromatography (TLC), Raman spectroscopy

and chemometrics, gas chromatography (GC), and capillary analysis. Paper analysis requires

chemical tests such as gas chromatography (GC), spectrometry (FTIR), and electron microscopy.

This paper examines several studies on the different types of scientific methods used by forensic

scientists to analyze both the chemical break down of pen ink and paper to aid document

examiners in their questioned document cases.

Literature Review

Bartick and Merrill’s (1992) research on ink analysis reviews the TLC method on

ballpoint pens since it is the most commonly used pen in forensic document examination.

Research states that the composition of ballpoint pen ink varies among manufacturers but

consists of a glycol-based solvent; a selection of dyes; resins, which are sometimes added to

adjust the viscosity of the ink; ball lubricants; and other proprietary additives used to improve the

writing quality(1). Thin layer chromatography is a simple organic chemistry procedure, or

process, that gives scientists a quick answer as to how many components are in the mixture and

identification of any present compounds. The procedure was broken down into five major steps.

First, a developing chamber was prepared with a 100 ml (milliliter) beaker and a watch glass on

top with 0.5 cm of solvent inside. It was then gently swirled and stood while the preparation of

the TLC plate was underway. A 5 cm x 20 cm white sheet was marked with a pencil line 0.5 cm

from the bottom of the plate known as the origin. Dots for each sample 1, 2, 3, and 4 were placed

on a line to mark the sample. Next, 1 ml of a volatile solvent (usually hexanes or ethyl acetate)

was placed on each sample mark to dissolve the sample. A microcapillary tube was used to tap

into the solven and lightly mark each sample. Then the magic began to happen. The TLC place

was placed in the developing chamber until the solvent reach 0.5 cm from the top of the plate

and was removed to air dry.

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