Forensic Science International, 26 (1984) 269-275 Elsevier Scientific Publishers Ireland Ltd.

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CHARACTERISTICS OF ERASABLE BALL POINT PENS*

ORDWAY HILTON

Examiner of Questioned Documents, P.O. Box 592, Landrum, SC 29356 (U.S.A.)

(Received June 1,1984) (Accepted August 24, 1984)

Summary

In 1979 shortly after the introduction of the erasable ball point pen two papers were published describing its basic characteristics (W.J. Flynn, J. Police Sci. Adm., 7 (1979) 346-349; P. Pfefferli and J. Mathyer, Rev. ht. Criminol. Police Tech., (1979) 407-419). Since that time two additional makes of pens and other colors of ink have been introduced, and the quality of writing has been significantly improved.

The ink of the erasable pen differs significantly from that of the standard ball point pen, and for that matter from ink of all other modern day pens. In what way might this newer pen produce a written line different from other ball point pens? This is one ques- tion that the paper addresses with limited success.

When erased, what techniques can be used to attempt to determine the text of the original writing? The writer considers all standard methods for deciphering erased writing and discusses modification by use of infrared film with oblique light photography -the method most successful in determining the original contents of the erasure.

Key words: Pens; Inks; Writing instruments; Handwriting; Erasures

The erasable ball point pen has a place among today’s writing instruments although it is not as commonly used as pens with standard ink. Still these pens are found in most office supply stores and in some other outlets where limited amounts of stationary and school supplies can be purchased. They are a relatively recent addition to the varieties of pens sold in this country, and it is well that the document examiner understands their characteristics that are different from other ball point pens.

Paper Mate introduced its Eraser Mate in early 1979. It contains an ink that when freshly written can be erased with relative ease. The pen is sold with an attached eraser similar to the wooden stick pencil. Some time after the introduction of the Eraser Mate, Scripto released its Erasable pen, and more recently Bit followed with an Erasable Ink pen. The original Eraser Mate ink was blue, but today Eraser Mate also supplies pens with black and red ink. Scripto produces pens with both blue and red ink but apparently not black. For Bit only a distinctive blue ink has been found

*Presented at the 1984 meeting of the American Society of Questioned Document Examiners, Nashville, Tennessee, May 20-25, 1984.

0379-0738/841$03.00 o 1984 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland

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in retail outlets. No other make of erasable pens has come to the attention of the writer.

The erasable ink is an entirely different formulation from inks found in other ball point pens. Shortly after Eraser Mate’s introduction Flynn pub- lished a description of the pen and its characteristics [ 11, and almost at the same time Pfefferli and Mathyer [2] published a more extensive study of the pen. Flynn describes the ink as similar to rubber cement, and his article contains a vivid Paper Mate illustration of its elasticity. When the writing is fresh the ink is loosely bonded to the paper, the characteristic that allows for easy erasing. There appears to be very limited initial absorption although this varies with different classes of paper. Not only can the fresh ink be removed by rubbing with an eraser but it can be lifted off the paper with any common press-on tape. In time the bond becomes stronger, but test erasing after the ink has dried for several weeks shows that it can still be partially removed with relative ease although the residue becomes as diffi- cult to efface as standard ball pen ink. Despite different ink formulation the written stroke of erasable ink is difficult to distinguish from writing of the standard ball pen, but can be readily differentiated from water based ink writing.

Because of the significantly different ink one might expect that erasable ink strokes would actually have a different appearance under the micro- scope. This was true with the early erasable pens. Their strokes displayed an irregular deposit of ink that was not typical of properly operating ball pens although a similar condition might be observed with worn ball pens using standard ink (Fig. 1). However, when such writing strokes are en-

Fig. 1. An example of poor quality strokes produced by some early erasable ball point pens. Note the irregular stroke density and the numerous skips and breaks along the line.

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countered one might suspect the erasable pen. Pens of all three manufactur- ers purchased in 1984 produced strokes of comparable quality as those of standard ball pens. This means that today differentiation based on the poor quality writing stroke is no longer possible.

With pens that the writer could locate in office supply stores in South Carolina and in Lower Manhattan, New York City, Eraser Mate pens utilize fine point balls while some Scripto pens are equipped with standard size balls, others with fine points. Bit pens seem to have limited distribution but those found had fine points. None produces a very heavily inked line.

One distinctive condition was observed with several erasable pens. Their strokes contain a number of clear breaks or pot marks, especially along the stroke edges (Fig. 2). This condition could be found with far less fre- quency in standard ball pen strokes and normally with some slight color- ation within the break. Further, the clear pot marks or small holes in the stroke were accompanied by skips or breaks in the line showing clear paper. When present this combination appears to be indicative of erasable ink. Otherwise there is no real difference between the two classes of ink stroke appearance under magnification.

Nondestructive ink tests do not suggest or help to distinguish these inks from standard ball pen inks [3]. Only black Eraser Mate ink absorbs infrared radiation. Examination under dichroic filters shows a slight reddish coloration with this black ink but none with blues. Infrared luminescence photographs

Fig. 2. Small pot marks or partial breaks along the edge of the writing stroke of erasable ink, some of which are indicated by arrows, may be found more frequently with erasable ink than with other ball pen inks.

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Fig. 3. The bright luminescence of Scripto and Eraser Mate red inks were the only two that luminesced on this IRL test. The Bit line above showed a very weak luminescence insufficient to be recognized in this reproduction. The sample sheet used for this test is reproduced in Fig. 4 where weak fragments of partially erased ink can be seen to the right of “hundred” but fail to reveal any visible luminescence in this area. The black Eraser Mate ink is shown black in this test.

reveal a very weak luminescence of red inks, both Eraser Mate and Scripto, and only a barely visible luminescence of a heavy Bit blue stroke when the writing is on cotton content paper without brightener (1950 bond used) (Fig. 3). This very weak luminescence is lost when a similar test is made with writing on paper with luminescent properties. Black Eraser Mate records as a dark line in both tests. Ultraviolet examination does not reveal any fluorescence, even of red inks. Thus the combination of these tests does not establish or point toward a conclusion that the ink is erasable.

Erasing and Decipherment

Immediate erasing of writing of today’s inks reveals that with bond and typewriter papers a total erasure frequently is very difficult to achieve. It is true of all three brands of blue and red ink. Pfefferli and Mathyer [2] observed similar results with the early Eraser Mate pen on some papers, and this writer has previously experienced such results. With some colored check paper the ink can be removed with ease, but the color of the paper, especially green, tends to hide the fragments of blue ink unless the area is examined very critically.

Erased area that are free from ink generally contain indentations of the original writing. It is true even when the writing was made with the paper resting on a bare desk top. Normally, effectively erased areas still contain some small fragments of ink, but study of the writing indentations, espe- cially in photographs with low angle illumination, are the best means of detecting an erasure and deciphering what has been erased (Fig. 4).

Pfefferli and Mathyer tested areas with iodine fumes, with Faurot’s

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Fig. 4. Sample writings and erasures of the available erasable pens are reproduced. The upper three are all blue inks, Scripto and Eraser Mate, very similar; Bit of a slightly different tint. The next pair are red inks and the following, Eraser Mate black. The early Eraser Mates were all blue inks. The erased “exactly” is revealed by side light illumination using a contrast emulsion (Kodak Contrast Process Pan) that emphasizes the indentations and fragments of ink.

erasure detection fluid, and with powdered Lycode as proposed by S.S. Kind [4 ] . They reported similar results with all three methods, and in most cases the erased area is revealed. Finally, they point out the importance of examining the writing under controlled lighting to locate the writing grooves of the erased material and to study them in order to decipher what has been erased.

As observed earlier the Eraser Mate black ink absorbs infrared radiation. However, infrared photography of black ink does not effectively intensify the writing, and consequently, decipherment of partially erased writing is not improved when infrared film and filters are used in conjunction with oblique light photography. If overwriting is present in the erased area and was prepared with erasable blue or red ink, the use of infrared film and low angle lighting can weaken the overwriting while recording the grooves from the original text (Fig. 5). In this way better decipherment of the erased material may be possible. As for infrared luminescence unerased red ink gives too weak a reaction to suggest that the procedure would be of any assistance in deciphering an erasure where some fragments of red ink are left. Such an erasure was part of the experimental photographs that tested for possible luminescence of erasable inks, and no luminescence at all could be observed in any erased area (Fig. 3).

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Fig. 5. Writing over an erasure in the area of “thousand” is deciphered by two techniques. The upper section shows some writing impressions revealed by oblique light photograph, but partially hidden by the overwriting. In the center section the photograph was made using infrared film and oblique light illumination. Ail blue ink strokes are eliminated, leaving only the indentations of the ball track. The strokes of “thousand” and the erased word appear with almost the same intensity and can be separated by careful study. In the lower section the erased word “hundred” has been inked over by hand to interpret the indentations.

Conclusion

Erasable ball pen inks differ significantly from standard inks, but the surest method of recognition is to attempt a mechanical erasure of a small fragment of relatively fresh ink. Visual study under magnification may reveal suggestive evidence that the ink is erasable. Direct infrared examination, infrared luminescence and dichroic testing may show clearly in some in- stances that the ink is not erasable, but never the cont.rary. Fortunately, the need to establish that erasable ink was or was not used may be en- countered very infrequently.

Deciphering what was erased is a more likely problem, and in many cases partial or better decipherments may be achieved. Study of the original ink under controlled lighting and oblique light photography are the prin- ciple means of solving the problem.

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References

1 William J. Flynn, Paper Mate’s new erasable ink pen. J. Police Sci. Adm., I (Sept. 1979) 346-349.

2 Peter Pfefferli and Jacques Mathyer, “Eraser Mate” un stylo a bille a encre effac- able. Rev. Int. Criminol. Police Tech., (1979) 407-419.

3 Ordway Hilton, Non-destructive test for field examination of writing inks and pens. J. Can. Sot. Forensic Sci., 12 (June 1979) 53-56.

4 S.S. Kind and M.D.G. Dabbe, The use of Lycode powders for the detection of erasures. J. Forensic Sci. Sot., 19 (March-April 1979) 175-178.

5 Ordway Hilton, Effects of writing instruments on writing details. J. Forensic Sci., 29 (Jan. 1984) 80-86.

6 Ordway Hilton, Distinctive qualities of today’s pens. J. Forensic Sci. Sot., 24 (May- June 1984) 157-164.