Journal of Criminal Law and CriminologyVolume 54Issue 3 September Article 17

Fall 1963

Pencil Erasures--Detection and DeciphermentOrdway Hilton

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Recommended CitationOrdway Hilton, Pencil Erasures--Detection and Decipherment, 54 J. Crim. L. Criminology & Police Sci. 381 (1963)

PENCIL ERASURES-DETECTION AND DECIPHERMENT

ORDWAY HILTON

The author is an Examiner of Questioned Documents, New York City, and Police Science Editorof this Journal. He is a member of the American Society of Questioned Document Examiners and aFellow of the American Academy of Forensic Sciences and has served as president of both organiza-tions. As vice-president and one of the convenors he was active in the First International Meeting inQuestioned Documents which was held in London in April 1963. This paper was presented at the 1962meeting of the American Society of Questioned Document Examiners.

Document examiners are frequently called uponto examine suspected erasures of pencil writing.Working records and informal documents are com-monly kept in pencil. From time to time they arechanged or altered, some in the course of prepara-tion, some to commit fraud. If the papers form thebasis of some phase of litigation or claims againstanother individual or corporation, the changesmust be disclosed and evaluated. It is the docu-ment examiner's task to reveal these facts.

How is PENCIL ERAsre?

Pencil writing is rather easily erased, but for-tunately, complete erasures are not nearly aseasy and as frequent as the layman believes. Pencilis usually erased by means of a rubber eraser.Many pencils are manufactured with such an eraseras part of the writing instrument. Occasionally, aproblem will be encountered in which the pencilwriting was scraped from the paper using a knifeor razor blade. Some people prefer to use an abra-sive type of eraser, such as the kind used for eras-ing typewriting. Emery paper and fiberglass erasersare sometimes employed. Chemicals as a rule arenot helpful, especially when we are dealing withblack pencil, since chemicals do not bleach thecarbon of the graphite. However, the use of hydro-gen peroxide solution has been reported (1). It hassome effect on loosening the bonding between thepencil graphite and the paper, making subsequenterasing easier.

A soft rubber removes most of the pencil rathereffectively. It disturbs the paper fibers far less thanthe more abrasive erasers. The latter may take thecarbon off a little more quickly, but even with thebest grade papers, there is danger of rubbing a holeor seriously roughing the surface. Skillful pencilerasures can be made so that it is almost impossibleto detect the presence of an erasure or subsequentlyto decipher what was erased. This class of erasurehowever is not too common.

WHAT IS LEFT?

Depending upon the original writing, the kind ofpencil used, and the skill and perseverance of theperson erasing, no original writing may remain, orvery little may have been removed from the paper.With very light original writing and careful andthorough erasing, all trace of writing can be re-moved. When a heavy pencil stroke was originallywritten, very prominent smudges of carbon maybe left or after diligent rubbing microscopic studywill disclose only small fragments wedged in thepaper fibers. The course of the original pencil strokemay be suggested by the greatest concentration ofcarbon fragments. With erased pencil writing, adefinite indentation or track of the original writingoften remains. More commonly there are combina-tions of these conditions which establish a weakfragmentary outline of the original writing. Theseremnants of the original writing form the basisupon which the document examiner works.

How ARE ERAsuREs DETECTED?

In order to detect a pencil erasure, one mustexamine the document carefully and critically.Several techniques are available. The first step is avisual examination under good lighting conditions.Diffused daylight is an ideal light, especially whenits direction can be controlled. Erasures often canbe detected more readily on a dull day. Brightsunlight or high intensity lighting may interferewith the detection of erasures rather than assist.While only crude erasures wear holes in the paper,other erasures tend to create thin spots. Conse-quently, every document suspected of having beenerased should be examined with transmitted light.In the course of visual examination, one shouldhold the paper almost at eye level sighting acrossit with the light coming toward the examiner. Forthis study it is often helpful to step back into acloset or a hallway so that the light strikes the pa-

ORDWA Y HILTON

per from only one direction. A spotlight or in-candescent light may be substituted for daylight orused as a supplementary step.

Examinations described should be directed to-ward discovering any evidence of a pencil erasure.This evidence includes partially erased writing inthe area under scrutiny, smudges of carbon orstains from the rubber eraser, indentations oferased strokes, disturbed paper fibers or thin spotsin the paper, differences in the reflective quality ofthe paper surface, or with colored or tinted paperdulling or weakening of color. If any of these condi-tions is present, it must then be carefully evaluatedto be sure that it is true evidence of an erasure.

Examination with hand magnifiers and thebinocular microscope of all suspected areas shouldfollow as a second step. Here again illuminationunder side lighting, either by daylight or with amicroscope spotlight, is helpful in disclosing rough-ened paper surfaces or slight indentations from theoriginal writing.

Dr. Wilson Harrison has developed a techniqueof detecting erasures by placing a piece of highlypolished, well cleaned, silver in tight contact witha paper at the suspected point (2). If a rubbereraser was used, the fact is disclosed by the tarnish-ing of the silver due to the rubber residue on thepaper. He reports that this technique reveals era-sures which cannot be established by any othermethod of examination.

How ARE ERAsuREs DECIPHERED?

In almost every case, the document examiner isultimately asked to determine what has beenerased. Pencil writing cannot be restored in thesense that by some type of treatment the originalwriting can be brought back again on the surfaceof the paper. Rather, it is a question of decipheringfrom the fragments and residues in the paper whatwas originally written. Methods of attack includevisual techniques, photography, and in some rareinstances, chemical treatment and physical ex-aminations.

Visual Methods. Visual techniques are the sameas those used to determine whether or not therehas been an erasure. The emphasis now is placedon determining what was originally written. Theorder of steps is repeated. One starts with unaidedvision and then supplements the study with handmagnifiers or possibly with a low power microscopeall coupled with carefully controlled lighting. Suc-cess depends upon a detailed study of the fragmentsof writing or of the writing strokes impressed in thepaper. Many erasures can be deciphered by these

means. The most useful lighting is subdued day-light which strikes the document principally fromone side or oblique side lighting from a spotlightwhich allows slight adjustments in direction andintensity. Oblique light is of help when there areindentations of the original erased writing left inthe paper.

In making visual examinations, attention mustbe given to the amount of magnification used. Tosome extent this is a personal choice, but in generalerasures are more easily deciphered under lowmagnification, if not by actual one to one examina-tions. Too much magnification, even as low as 2 jto 3 diameters, may restrict the decipherment.Some workers prefer to use a reducing lens to con-centrate the writing fragments and thus intensifythem by virtually connecting them.

The quality of light for visual examinations isextremely important. Diffused daylight, especiallyfrom a north window, has extremely good quality.It has been this writer's experience that dull ratherthan bright days supply the best quality of lightfor deciphering erased pencil writing. Artificiallight, unless it can be directed from one side of thedocument at relatively low intensity, is not toosatisfactory. Many times overhead fluorescentlighting creates light in which it is very difficult toexamine erased pencil writing successfully. Withall types of light, better results are obtained if thelight is not balanced but more concentrated on oneside of the paper. The paper should be examinedwith the light coming from the right and then fromthe left, from the top and then from the bottom.Sometimes intermediate directions are helpful todecipher completely and to prevent false deter-minations.

Among the available types of artificial lightsources, the spot illuminator with a variable in-tensity rheostat is particularly useful since it permitsadjustment both in the direction and intensity oflight. Writing indentations can often be effectivelyintensified and deciphered by the skillful adjust-ment of the direction of the spot, its angle relativeto the paper surface, and its intensity.

A helpful technique in examining erasures is tolet them "age." Problems may prove to be morereadily deciphered after they have been aroundthe laboratory a few days than when first presented.A possible explanation is that a slight accumulationof dust collects in the writing indentations, thusintensifying them.

Photographic Methods. Photographic methods arein fact an extension of the visual techniques. Inthis way a permanent record is made of what can

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be seen, but the most important role of photog-raphy is its ability to intensify slightly the weakfragments that are present so that they can bebetter interpreted. A series of different types ofphotographs can be prepared, combining differentlighting and emulsion characteristics to achievethe most complete decipherment.

No single photographic method is completelysuperior to the others in the detection of erasedpencil writing. Several techniques give consistentlygood results, but unless complete decipherment isachieved by the initial attempt, it is desirable totry two or three different methods. The methodsthat are commonly employed include.a carefullymade photograph in which the contrast is increasedslightly, a photograph with a high contrast emul-sion sometimes incorporating special developmenttechniques, a photograph with low angle (oblique)side lighting, a long exposure photograph with alow intensity light source, an infrared photograph,and a color photograph. While each method is tobe evaluated, we must recognize that a successfulphotograph incorporates the maximum detail withsome increase in contrast. Contrast at the expenseof sharp detail or detail at the expense of good con-trast usually restricts decipherment. In all photo-graphs of erased pencil writing a snappy print withfull detail effectively records all of the partiallyerased fragments.

There are certain erasure problems in which agood photographic copy of the questioned docu-ment will disclose what has been erased. The useof standard emulsions, such as Eastman Pan-atomic-X, coupled with developers and developingtechniques to give above average contrast, are tobe recommended. Certain filters, such as a Wrat-ten K-2 or K-3, may improve the photographs.Excessive contrast is not necessarily the ultimategoal.

Improved results can generally be obtained byspecial photographic methods. One of the most ef-fective in this writer's experience is the use of lowintensity lighting directed from one side of thedocument (3). If daylight is the source, these pho-tographs are more easily made on dull days. If itis necessary to proceed on a brighter day virtuallyclose the blinds so that exposure time at 1 to 1 sizeand f. 16 stop requires at least 10 to 20 seconds.The slight outline of unerased pencil writing or theindentations from the original writing appear tobe more easily recorded by such techniques. Pan-atomic-X film with a developer which producesmoderately sharp contrast is recommended.

With erased pencil problems, the control of

lighting is highly important. Side light photo-graphs, especially with light directed across thepaper at a very low angle, is particularly helpfulwhen there are writing indentations in the paper.If there are no indentations, then this type of pho-tography as a rule is not of value. With a badlyroughed paper surface this kind of light mayemphasize the erasure but confuse decipherment.Oblique lighting in photography, as in visual ex-aminations, creates shadows along the indentations,thus intensifying them. With this technique it isoften helpful to prepare several different photo-graphs in which the direction at which the lightstrikes the paper relative to the line of writingshould be changed in at least units of 90'. Thus,the light comes from the top, the bottom, the left,and the right. At times, it is also desirable to changethe angle between the light beam and the papersurface. Extremely acute lighting, less than 15,may intensify even slightly disturbed paper fibersso much that they and the indentations are badlyconfused, whereas light from a less acute angle maystill intensify the indentations without emphasizingthe paper fibers.

A useful tool in preparing side light photographsis the unit developed by the Royal CanadianMounted Police Laboratory (4). It is a box whichprovides a flat bed and a suction unit to hold thepaper absolutely flat. The scheme of moving theexposure slot and enclosed light across the sheetseveral times provides oblique lighting but a bal-anced negative. Books and very large sheets ofpaper may not be accommodated, but standard sizepapers can.

Contrast emulsions, such as Eastman ContrastProcess Panchromatic or Kodalith film may assistslightly in photographing erased writing. Theseemulsions can be combined with any suitable typeof lighting techniques, and some workers preferthem to lower contrast emulsions. Over the courseof years with comparable exposures, a contrastemulsion showed better results than Panatomic-Xin some problems, but on other occasions, the re-sults were decidedly inferior.

Eastman Kodak recommends a special techniquewith Kodalith film and weak writing traces. Thefilm is exposed normally and then developed in atray without agitation. Slightly better than usualdetails of the weak writing are reported, but thiswriter has not had particularly gratifying resultswith the technique. Tuttle has also suggested usingKodalith film to make a contact print with thedocument as the negative (5). Results of themethod have not been observed by this writer.

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The almost classical method of photographingerased pencil writing is with infrared sensitivefilms and plates. To read many writers, this is themethod. If it were only true, solution of theseproblems would be far simpler. There are instancesin which infrared photography gives excellent re-sults; in others it gives about the same results asother techniques as far as completeness of decipher-ment. In theory, it is supposed to intensify the weakpencil traces. It does if there are slight fragmentsof pencil writing left, but these fragments can alsobe intensified by other photographic methods.There are no hidden bits of carbon buried in thepaper since all of the pencil writing is depositedon the paper surface and the erasing process is di-rected toward removing these surface deposits.It is probably more effective than other techniqueswhen the original writing was done with a softpencil in which the erasing has left some smears oforiginal writing without significant indentations.When a hard pencil has been used, which createdpronounced writing indentations and the erasinghas successfully removed the carbon, other methodsare more effective. If ink is used to write over theerasure and the ink is not recorded by infrared, aninfrared photograph eliminates the interferingoverwriting and makes decipherment easier. The-writer has also experimented with a combination-of infrared and side light photography and at timesfound it helpful.

Selection of infrared emulsions are important.The ordinary Eastman infrared film works satis-factorily, but does not give the highest quality re-sults. Better results are obtained with infraredplates which have somewhat higher contrast andimproved resolving power, such as Eastman Infra-red Spectroscopic plates with a type N emulsion.However, as is true with all document photography,the particular emulsion used depends upon personalpreferences. With experience, slight modification inhandling may mean that two workers using differ-ent materials will obtain comparable results. Thewriter has never attempted to develop infraredplates or films to their highest contrasts.

Discussion to this point has dealt primarily withthe erased writing which had been prepared with ablack pencil. If colored pencil writing was erased,infrared film is ineffective, although all other pho-tographic and visual methods are applicable. Addi-tion of a photographic filter which contrasts withthe color of the erased writing, for example redwith green writing, may improve results. Witherased red pencil, orthochromatic or color blind(blue sensitive) film is recommened.

Only limited experiments have been made withcolor photographs of erased pencil writing. If colorbalance is to be maintained, then photographs mustbe made and processed without manipulation ofexposure times or processing techniques which arecommonly employed in black and white photog-raphy. Color photographs of erased pencil writingreveal that the emulsions record partially erasedwriting as well as black and white emulsions, andunder some conditions the color reproduction couldbe preferred. Possibly further work with theseemulsions may develop techniques which in a par-ticular case will give results superior to black andwhite photographs.

Processing of negatives in erased pencil writingproblems is somewhat of a personal preference.Almost all examiners have photographic solutionswhich they like, and for the most part these are tobe recommended in preference to some specificsolution. Familiarity with a developing formulaand how negatives can be manipulated in it to con-trol contrast and density generally leads to betterresults than using a special developer only occa-sionally. Still we must not stop looking for an im-proved processing method. The writer in recentexperiments found that in addition to a standarddeveloping solution, which he uses for processingof all negatives, Eastman's recommendation of de-veloping Panatomic-X film for greatest sharpnessby using Microdol-X developer, diluted 1 to 3 asindicated on their data sheet, gives a very highquality result. Some workers may prefer to use aspecial high contrast developer. Microdol-X is notthis type and tends to substantiate the theory thatdetail is as important as contrast in erased writingproblems.

In printing from negatives, several grades ofglossy paper should be used and slightly differentdensities of prints should be made with each. In thisway, the best print can be chosen, since there seemsto be differences from problem to problem as towhich grade of paper is going to give the most com-plete decipherment. It must be recognized that sel-dom can a pencil erasure be effectively decipheredby making one negative and one print.

Improvement in the final photographs may resultfrom special treatment of the negative-reductionand intensification. The best negative is bleachedwith Farmer's reducer and then intensified withappropriate solution to increase contrast slightly.Similar results may be achieved by rephotograph-ing the print which represents the best decipher-ment. Both techniques require experience and skill,

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and a more complete decipherment cannot alwaysbe guaranteed.

In all erased pencil problems, the back of thesheet should not be neglected. When there is writ-ing on only one side of the page and the originalwriting caused some embossing, it may be possibleto get a better photograph of the original writingfrom the back side than from the front. The posi-tive, of course, is made by printing with the emul-sion side of the negative down so that the decipher-ment reads normally.

Overwriting in the erased area often seriouslyrestricts decipherment. When possible, a photo-graph which eliminates or weakens the secondwriting should be made. For example, with infra-red transparent overwriting an infrared photographachieves this result while with colored overwritingproper selection of a filter weakens it. But usuallywriting over erased pencil is black pencil. Gayethas proposed preparing a photograph which re-cords primarily the overwriting. A positive trans-parency is made from this negative. The negativewhich best deciphers the erasure and this positivetransparency are superimposed, and a print is ob-tained in which the overwriting is virtually elimi-nated and the deciphered erasure is better revealed(6).

One of the greatest advantages in photographicmethods of deciphering erased writing is that pho-tographic prints can be marked in the course ofexamination and decipherment. A technique that isextremely useful is to mark every fragment, letter,or word which can be deciphered from the printwith colored ink or pencil. Thus, if several printsand the original document are being studied simul-taneously, it may be that some parts of the writingcan be better deciphered from one than from an-other. When all of this information is recorded on asingle print, it can be collated and more extensivedecipherments can in this way be achieved.

Chemical Methods. Chemicalmethods of decipher-ing erased pencil writing are limited, and for themost part are not highly recommended. An iodinestaining solution, such as the one patented someyears ago by Ehrlich (7), depends upon a differen-tial absorption of the paper where there has beenpressure due to writing and where there has beennone. When the back of the sheet is treated, theentire sheet is stained, but the outline of writing,both erased and overwriting, is developed in adeeper color than the surrounding area. However,the solution is not too reliable. It tends to reactdifferently on different papers sometimes destroy-ing all evidence without producing any results. It

also develops latent fingerprints and smudges fromthose who handled the paper. The difficulty in re-moving the stain with hypo without leaving someevidence of treatment means that the techniqueshould only be used when all other methods failand when there seems to be some chance that itmight add something to the decipherment.

Indented writing is sometimes developed by fum-ing the sheet with iodine, especially in a fumingchamber where the action is slow. When similarindentations are present in an erasure problem theymay be developed by this technique. Handling thesheet during erasing and subsequently oftentimescauses latent finger smudges and fingerprints to bedeposited, and the iodine develops these. Besides,the disturbed paper surface and fibers tend to in-terfere. While iodine fuming may assist in an oc-casional case, it cannot be highly recommended.

Alcohol spray may help to decipher an erasureof copy pencil writing according to Longhetti andKirk (8). When all the dye stuff, which is added tothe graphite of these pencils, is not removed byerasing, the alcohol reacts with it to develop itsfull blue or purple color. Application by means ofa nebulizer gives a fine spray which does not seri-ously harm the paper. In addition these erasurescan be deciphered by the same procedures as anyother erased pencil problem.

Other Methods. The use of infrared viewing equip-ment in connection with erased pencil writing maybe of slight assistance. However, infrared photog-raphy is more effective. Nevertheless, in the courseof visual examination the viewer has value. Againcareful manipulation of the light source and thepaper aids in decipherments of difficult areas, andsupplementing other techniques the infrared viewermay lead to more complete results.

Several years ago, Longhetti and Kirk suggestedthe use of plastic replicas as a means of decipheringwriting impressions (8). The technique consists ofsubjecting a thermo sensitive plastic to heat froman infrared light source, while the plastic and paperare held in tight contact by weights. When theplastic flows slightly, the heat is removed, and theplastic is allowed to reset. After separation fromthe paper, the plastic sheet with the indentationsimpressed on it can be manipulated readily, and theindentations are said to be easier to read. Thiswriter has experimented with the technique onseveral problems, but has not found it to be suffi-ciently effective with either erased or impressedwriting problems to warrant its use in place ofvisual and photographic techniques. One must de-velop proficiency in handling the plastic to get the

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ORDWA Y HILTON

best results, and there is some slight danger ofdamaging the evidence due to its occasional stick-ing to the plastic surface.

Several years ago, Godown suggested the use ofRonchi rulings as an aid in reading impressedwriting strokes and erased pencil writing (9). In ameasure these rulings are of value in decipheringerased writing. With some material they have atendency to intensify letters and words which canbe dimly seen, especially when these are princi-pally indentations in the paper. The plate is laidin tight contact with the paper, and the light sourceadjusted for the best reading. However, experi-ments show that there is a certain cut off point atwhich the rulings seem to eliminate any weak frag-ments. Thus, very weak writing is entirely lost,while somewhat stronger fragments are slightly in-tensified. When using the plates, examinationsmust be made without any magnification since themagnifier separates and enlarges the rulings andthus destroys the effect of their fine ruling and spac-ing. Ronchi rulings do have limitations but mayassist in an occasional case.

Polarized light has been considered as a possi-bly superior type of illumination for visual andphotographic examinations. After extensive experi-mentation with it, however, this writer finds thatit has no particular merit as an aid in decipheringerased writing.

Filtered ultraviolet radiation does not help verymuch in deciphering erased pencil writing. Withblack pencil there is no special fluorescence notedas with some ink erasures. Some red pencils dofluoresce brightly and with such material ultra-violet may help. Occasionally, it is of some as-sistance in examining an erasure of black pencil. Ifthere is some doubt about the decipherment, ultra-violet examination may confirm an interpretationthat fragments are actually graphite deposits andnot merely "fanthom strokes." Certain papers ap-pear very different under ultraviolet than underordinary light, and the change in contrast broughtabout by ultraviolet between the paper and thefragments of erased writing is occasionally of value.

CONCLUSIONS

The techniques described in this paper are themore common and most effective ones. Havingtried the various methods described, the writerprefers photography. In the majority of casesphotographs produce the most complete and satis-factory results.

After all of the techniques have been applied to apencil erasure problem, there is generally need forcareful evaluation and interpretation. A number ofthe decipherments is clear, but some problems aremore difficult. In the decipherment of certainerasures one must interpret the meaning of frag-ments to form a judgment or opinion as to whatappears to have been erased. It may even be neces-sary to establish first that a fragment is actuallyerased pencil and not a crease or smudge. When anerasure is studied at length, it is always advisable,if possible, to put the problem aside for a periodof time and to come back to it later. If this is notpossible and the decipherment is marginal, it isadvisable to have some impartial observer or an-other expert critically inspect the findings. An oc-casional shadow in a photograph, a small crease inthe paper, or an indentation from some sourceother than the erased writing can fall in the area inquestion and be misinterpreted unless the greatestcare and critical review are applied. Fortunately,with many problems, these trouble spots are re-duced to an absolute minimum by patience and thetechniques described.

REFERENCES

1. Donald Doud, Milwaukee, Wis., (personal corre-spondence) reported and furnished examples ofthe technique. He has references to original papers.

2. WILSON R. HARRISON, SUSPECT DocuMENTs, T EIzScIENTIFIC EXAMINATION, Frederick A. PraegerPublishers, New York, pp. 103.

3. ORDWAY HILTON, Photographic Methods for De-ciphering Erased Pencil Writing, INTERNA-TIONAL CRIMINAL POLICE REvIEw, February1955.

4. N. W. DUXBURY AND J. W. WARREN, Decipheringand Photo-Recording of Indented Writing,ROYAL CANADIAN MOUNTED POLIcE LABORA-TORMS, SEMiAR No. 4, Examination of Ques-tioned Documents, pp. 27-36 (1956).

5. Harris Tuttle, Eastman Kodak Co., Rochester,N.Y., (personal correspondence).

6. JEAN GAYvT, A Method of Superimposed Photog-raphy Applied to Criminalistics, JOURNAL OFCRIMINAL LAW, CRIMINOLOGY, AND POLICESCIENCE, Vol. 44, No. 3 (September-October1953).

7. Josef Ehrlich, U. S. Patent, No. 2,123,597, July 12,1938 (patent rights have expired). A second solu-tion is reported in H. T. F. RHODES, FORENSICCHEmsTRY, 1940 at page 135.

8. ANTHONY LONGIETTI AND P. L. Kinx, Restorationand Decipherment of Erasures and Obliteratedor Indented Writing, JOURNAL OF CRIMINALLAW AND CRmmOLOoY, Vol. 41, pages 519-22(1951).

9. Linton Godo-wn, Chicago, Ill., (personal corre-spondence), in which he quoted from a publica-tion of Edmund Scientific Co. pamphlet dealingwith the use of Ronchi rulings.

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