Paper analysis is an important element in determining the genuineness of forensic questioned documents. In all circumstances, confirming the authenticity of the document itself is a conclusive method of determining forgery.
And here, paper forensics is quite important.
So, how does forensic analysis of papers assist forensic document examiners (FDEs)?
This is what this length post is all about. But if you’re willing to read it all— be my guest. I’ll be happy.
And if you want to skim the post, the following is a table of content.
Need And Purpose of Forensic Analysis of Paper
Following are the common fruitful forensic information that can be extracted from the paper analysis:
- What nature and source of raw materials (pulp) are used?
- Produced by which company or machine?
- What type of manufacturing process is used?
- Latent writing or impression restoration?
- Absolute age determination of document using paper dating.
- Reconstruction of cut and shredded papers by physical edge match.
- Imprint examinations: faded, hidden, invisible, obscured, chemically erased writing.
- Document preparation and sequence determinations.
- Fabricated, obliterated, and authenticity of papers and security documents.
- Restoration and decipherment of arson papers (Charred documents)
- Restoration of water destroyed papered documents.
Types of Papered Questioned Documents
K. M. Koppenhaver stated a list of 101 different types of papers commonly encountered as evidence in forensic cases. From all, I listed the top 51 documents, including:
|S.No.||Forensic Questioned Document|
|5||Automobile Insurance Papers|
|6||Automobile License Papers|
|7||Bank statement, and other slips|
|8||Bills of sale|
|12||Cheques and passbooks|
|16||Credit and debit card charge slips|
|17||Deeds of trust and deposition|
|18||Diploma and educational certificate|
|20||Drivers licenses and applications|
|22||Envelopes and addresses|
|24||Leases and property papers|
|25||Letters: personal and business|
|26||Life Insurance papers|
|30||Medicare cards and papers|
|32||Newspaper and magazine|
|33||Occupational and membership card|
|34||Parent’s signature and child custody|
|37||Pensions acknowledgment papers|
|38||Permit and petitions|
|43||School and college papers|
|44||Social security cards and papers|
|45||Sport and game scorecards|
|46||Stock certificates and papers|
|47||Tax returns and slips|
|48||Telephone service reports|
|50||Voting Registration records|
Questions To Be Asked by Forensic Document Examiner
The following are the questions that you as an examiner must ask to come up with the final conclusion of the report.
Q1: What type of paper?
Ans: Security, cheques, identification, etc. (above listed)
Q2: Do all pages have the same uniformity in multi-paged documents?
Ans: Check for the uniformity characteristics such as size, thickness, color, margins, and weight throughout all pages of the document.
- Weight (grammage): Range 32 gm-2 to 225 gm-2 with max 7% of variation.
- Thickness: average of 5 to 6 measurements.
- Ink bleeding through paper can define the thickness.
Q3: Do paper documents have watermarks?
Ans: Many security pages, notary documents, and some manufacturers use their company logo or initials as watermarks.
- Check for them thoroughly on every page.
- Inspect the direction, dimension, and opacity of watermarks.
Q4: Is there any physical damage?
Ans: Physical damages such as staples, adhesive marking at the edges, folds, etc.
- If stapled, check if all pages have them or not.
- Check for the consistency of stapled holes.
Q5: Are there any marks or ridges on the paper?
Ans: This is important. FDEs should look for fingerprints or palm prints.
- Helps in individualization.
- The best way to find them is to use alternative light sources.
- If they appear, photograph them in alternative light.
Please Note: If fingerprints appear on a questioned document, and can’t be developed using alternative light, and chemical development is needed, in that case, no efforts are needed to develop them. Know more: 14 Myths of Fingerprints on Questioned Documents.
Q6: Any other trace evidence on paper?
Ans: Blood, sweat, soil, paint, hair, etc. over the paper.
Q7: Any sign of damage or torn?
Ans: Burnt, water lodged, torn, or shredded papers are common.
- Water lodged and burnt papers (charred) need extra attention.
- For torn and shredded papers, try to fix them according to suitable fit and matching.
Q8: Are papers originated from printers?
Ans: Check for the indentation due to grip marks from a printer feeder.
Q9: Is paper-lined? Which type of lines are used?
Ans: Following information needed to look for:
- Single, double, cross lined pages
- Color of lines
- Number of lines per page
- Space distribution among lines.
Q10: Any sign of indentation?
Ans: Use an alternative light source to examine for indentation. Use ESDA for development.
Q11: Do papers have crumbles?
Ans: Crumbleness could help in determining the prior condition of the questioned document.
- Crumbling forms random ridges over paper that vary with density. This could be a sign of destroying or hiding evidence.
- Crumbled papers usually are soiled papers (napkins or tissue paper).
Q12: Any sign of cuts?
Ans: Type of cuts states the means of the cutting tool.
- Scissors and blade cutters produce sharp and smooth edges.
- Cutting levers produce dented smooth edges.
- Abruptly cut (tearing) results in fibered edges.
Q13: Fadeness, discoloration, or stain over paper?
Ans: Helps to define the prior environmental condition:
- Extended exposure to heat and light cause fadeness and discoloration
- Reprinting cause discoloration
- Stains due to sweat drops, raindrops, spilling of tea, and other beverages.
Q14: Is there any sign of erasures or secret writing?
Ans: Ethanol helps to remove ink from paper but they are easily identified by various decipherment techniques. Check for them in an alternative light.
Preliminary Caution Before Examination of Paper
A. Maintaining Temperature and Humidity at Laboratory
As per the International Organization for Standardization (ISO), the favorable condition for paper testing is:
- Relative humidity: 50 ± 2%
- Temperature: 23 ± 1°C.
But why is maintaining laboratory temperature and humidity important in Forensic Paper Examination? Because paper readily absorbs moisture from the surrounding. The absorbing percentage is about 5 to 12%. And the amount of moisture absorbed affects the following properties of paper:
- Page weight
- Tearing force
- Optical properties such as opacity and dullness
Quick Science: The absorbing % is defined by the equilibrium between water absorbed and vapor in the surrounding area in contact with the paper.
Apart from storing, absorbing factors also depends upon:
- Paper type: glossy layered paper absorb less compared to rough surface paper
- Position of a specific page in the multi-paged document. The first page absorbs more humidity, less by the second page, and so on.
Thus, the examiner should take humidity and temperature into consideration.
B. Anisotropic Properties of Paper
Commercially manufactured papers have anisotropic properties that are the cause of variation in physical properties towards the plane of sheets.
These minor variations are due to the term known as ‘grain,’ which refers to the direction of fibers.
Grains are of two types.
- Long grain: along the longer axis of a rectangular manufacturing sheet.
- Short grain: along the shorter axis of a rectangular sheet.
Grains analysis is done by tearing paper. This is how it is differentiated.
Forensic Importance: Forensic analysis of papered grains helps in defining whether a sheet is from a batch or not. The analysis also states (not conclusively) the differences in values of:
- Tensile strength
- Tearing strength
Therefore, there is a high possibility of variation in the physical and optical properties of paper. So, a QDE must take all these into consideration.
Forensic Testing and Examination of Papered Questioned Document
There are numerous tools and examinations that an FDE may use to define the authenticity of questioned documents.
The following is the set of examinations and analyses with respect to papered documents.
- Preliminary examination
- Optical examination
- Physical examination
- Watermarks examination
- Fiber and Pulp Analysis
- Chemical analysis
- Instrumental analysis
- Absolute age of paper
Some of the special cases in Forensic Paper Examination:
- Analysis of burnt or charred documents
- Restoration and analysis of water destroyed documents
- Analysis and restoration of shredded and torn documents
A. Preliminary Examination And Documentation
Step 1. Maintain the chain of custody
When a questioned paper document is received at the lab, the examiner must sign the chain of custody and check for the seal.
Step 2. Maintain Case Note
All the changes such as removing staples, paperclips, separating sheets from a bundle, etc., and examinations such as macroscopic and microscopic shall be documented in a case note.
Step 3. Imaging
Imaging presents the condition of QDs received by FDE. It also removes any liability about the evidence’s prior condition before it reaches the Forensic document unit. While imaging, it also ensures the accuracy of color and finer details of received sheets should be at a higher resolution (300dpi).
Step 4. Pre-Documentation of Visible Details
After imaging, the next step is to note all the visible details on the received documents. These may be:
- Number of pages/items received
- Overall conditions of papered documents.
- Type of document
- Printed, handwritten, stamped, blank
- Latent prints, any secret handwriting (Alternative light source)
- Indentation impression
- Adhesive marks
- Staple, clips, or folds
- Irregularities in color, dimensions, file-holes, watermarks on paper
- Irregularities in typestyle, text formatting, and writing instruments.
- Sign of physical alterations.
Step 5. Roadmap of Analysis:
Every analysis is different. Evaluating the received documents helps the QDE to take the right decision on which analysis should begin with.
For example: If a paper has latent fingerprints, indentation marks, or any secret handwriting, their development should be taken into consideration. Because starting with chemical and instrument analysis can lead to the destruction of this evidence.
B. Optical Analysis of Paper
Optical analysis refers to the experimental determination of four basic properties. These are:
- Finish and coating (gloss)
- Brightness and
- Instrument: Microspectrophotometer
Defining the color can help to differentiate between two colored papers. Typically, the examiner determines color by visual examination under ambient light.
However, as a forensic expert, you can’t simply go to court and say, “Both the questioned and reference samples have the same colors.”
You should prove your claim.
To do so, you should first photograph both samples in ambient light.
Secondly, to make it more accurate, you can use a forensic color chart (like Munsell color chart) or color determining software to present your findings.
This way, one doesn’t have to rely on the differencing ability between two colors of QDE.
In modern questioned document laboratories, color is determined by visible spectral reflectance spectroscopy (microspectrophotometer). This also aids in the identification of different dyes in a sheet.
2. Finish and Coating
Not all papers are coated. But a majority of them have.
They are coated with different surface modifiers to impart certain qualities. Qualities such as weight, glossiness, smoothness, ink absorptions, etc. are added by surface coating films.
There are three types of surface finishes:
a. Gloss finish paper:
- Tends to shine
- Gloss coating on single or both side
- Less opacity
- Ink absorption is low (that’s why excellent color representation)
Quick Note: Glossmeter:
-> Glass meter is a device to measure the amount of glossiness of a papered document.
-> It is calculated by the ratio of reflected light to falling off a papered sample.
Know Continue Reading: Instruments Used in Forensic Science.
b. Satin finish paper:
- Less shiner than gloss
- Produce sharp and vivid color representation
- Used mainly for exhibition photos
c. Matte finish paper:
- More opaque than the other two
You can skip this step if the questioned document sheet is non-photographic paper. They are exclusive for characterizing the glossed papered samples.
3. Paper Brightness
The brightness of paper refers to the percentage of blue light reflected from the paper surface as measured at a specific wavelength of 457 nm.
The brightness value is displayed on a scale of 0 to 100%. Higher the number, the more light it reflects and the brighter the paper.
In general, the standard bright value for commercially available paper ranges between 90 to 100.
To make the paper brighter, manufacturers add Optical Brighteners Agents (OBAs). These chemicals absorb light in the UV region (340-370nm) of the spectrum and re-emit light in the violet/blue region (420-470 nm).
To measure brightness, there are 3 main systems. These are:
- TAPPI/G.E Brightness
- ISO Brightness (most widely used)
- D65 Brightness
You can learn more about how to measure the brightness of paper and which testing tool is used from How to Measure Paper Brightness? A Forensic Guide
Apart from OBAs, there are fluorescent whitening against (FWAs) that produce a fluorescence effect.
The intensity of fluorescence can significantly differentiate between two papers of the same color and brightness level.
For instance, let’s say Paper ‘A’ and ‘B’ have the same shade of white with nearly the same brightness level of 92, but Paper A has FWAs.
In this case, Paper ‘A’ can easily be differentiated from paper ‘B’.
To know whether FWAs are present or not, observe the paper in dark by irradiating short (250 nm) and long (350–390 nm) UV light. And for spectral analysis, a Spectro-photo-fluorometer can be employed.
Lastly, factors such as age and exposition to light can decrease the fluorescence intensity with time.
4. Opacity of Paper
- Instrument: Opacimeter
The amount of light a paper can transmit through it is defined by its opacity.
Though, like other optical metrics, it also subjectively depends upon how fainter you see the background. It is also viable to determine how much darker prints are visible from the reverse side of the paper.
Reason of Opacity in Paper
- Higher the cellulose fibers percentage in the paper, the higher the opacity value.
- Filler such as clay, titanium dioxide, and calcium carbonate to increase the diffusion of light (increase in opacity)
- Tinting and dyeing increase opacity
- Paper whiteness decreases opacity
- Coating decrease opacity
How to measure the opacity of paper?
There are two distinct methods to come up with the opacity value using an opacimeter. First is the contrast ratio, and the second is the diffuse opacity method.
a. Contrast Ratio Method: Ratio of the amount of light reflected back through a paper with a black background to the same paper with white background.
b. Diffuse Opacity Method: Ratio of light reflected back through a paper with a black background to the stack of papered sheets.
One of the common commercial opacimeter is EEL 12M Opacimeter.
C. Physical Examinations of Paper
One rule of thumb is: forensic analysis should always begin with non-destructive methods.
Most physical analyses are non-destructive and typically enough to demonstrate the distinction between two papered samples.
But.…. It can’t state conclusively about the same papered samples. It only states that they may be the same and further analysis needs to be done.
Therefore, a forensic document examiner always begins with a physical examination and then moves to other analysis methods.
1. Dimension of Paper
- Instrument: Ruling scale (plastic, L- shaped ruler)
- Units: millimeter
Finding dimensions of papers is important not only to come up with the grammage value (later in the post) but to find any sign of additional pages.
Following are the common dimensions of standard sheets.
|Sheets||Dimensions (length x width)|
|A0||1189 x 841mm|
|A1||841 x 594mm|
|A2||594 x 420mm|
|A3||420 x 297mm|
|A4||297 x 210mm|
|A5||210 x 148mm|
|A6||105 x 148mm|
|A7||105 x 74mm|
|A8||74 x 52mm|
All ‘A’ series sheets are arranged in a fashion that at cutting, no wastage occurs.
The A1 and A2, A3, and A4 share a ratio of 1:√2 dimension to dimension of the sheet (A0). Similarly, the rest ‘A’ series are arranged.
This is how it looks.
This is the reason why different A series sets have different fiber arrangements called grains.
Forensic Importance: These sheets are not cut exactly to the above dimensions. The variation range from
- Long grain: up to 4%
- Short grain: up to 1.5%
This variation of the dimension is due to expanding and contraction ability of paper at the time of cutting. So, QDEs must take an accurate measurement of sheets using a suitable scale.
2. Basis Weight (Grammage)
- Instrument: Analytical weighing machine with milligram scales
- Units: grams and converted into grammage (rarely imperial)
Grammage (gsm) is defined as the weight of paper in grams per square meter. Most federal and privately questioned document agencies use the grammage system.
- 35 to 55 gsm: lightest types. Used as tracing paper to newsprint papers
- 75 to 90 gsm: Very common. Used by various printing and photo printing machines
- 90 to 120 gms: Usually used for craft works, bonds, and posters
- 120-140 gsm: Promotional posters
- 210-300 gsm: Magazine and book covers
- 350-450 gsm: sturdiest paper for quality invitation cards or book covers
Quick Note: Generally, for imperial weighing, 1lb. of paper = 1.48 gsm
How to calculate paper grammage value?
Follow the following step:
- First, find the area using dimensions of sheet
- Finding the weight of a single sheet
- Calculating factor value (defined by the number of sheets per square meter)
- Grammage= factor x weight
Example: A4 sheet with observed dimension 298 x 210 mm and observed weight is 4.72 grams. Calculate grammage?
- Area of A4 sheet: 298 x 210= 62580 mm2 = 0.06258 m2
- Weight of single sheet: 4.72 grams
- Factor value: 1/area = 1/0.06258 = 15.9795
Grammage Value= 15.9795 x 4.72= 75.423 gsm.
Variation in Grammage: Basis weight may vary among the same batch of producing sheets. It is majorly because of moisture absorption by paper from its surroundings.
Moreover, modern machines are pretty accurate. Sheets grammage should not vary by more or less than 2%. However, the following are the acceptable variations in a multi-paged questioned document for documents generated using older machines.
|Grammage Value||Variation (%)|
|Below 33 gsm||±2.5|
|30 to 59 gsm||±6 to ±8|
|60 to 179 gsm||±5|
|180 to 224 gsm||±6|
|225 gsm and above||±7|
Grammage value depends on several factors such as:
- Pulp type
- Refining of pulp at manufacturing
- Filler content and chemicals
- Adhesive absorption
Variation above 10% is highly unacceptable.
The main reason for the higher variation is possibly due to chemically thinning or heat application. But it can alone be descriptive about its authenticity.
So, the questioned document examiner has to come up with other relative values such as paper density and thickness.
3. Sheet Thickness (Caliper)
- Instrument: Dead Weight Thickness Micrometer
- Units: micrometers (µm)
When it is impossible to find the basis weight, evaluating thickness comes in handy. Cases such as fragments, shredded, partially burned papered documents are encountered, it is nearly impossible to determine the exact basis weight.
Taking thickness measurements:
- Calibrate micrometer with std A4 sheet.
- Take 5 to 10 measurements from different areas of the sheet.
- Average them to get single sheet thickness
How to Use Dead Weight Paper Micrometer?
-> The most suitable micrometer for finding the accurate thickness of the paper.
-> Paper is placed on a larger base and pressed by a circular wide diameter foot (approx. 16mm) with a steady platen pressure up to 1 Kg/cm2 (98.0 Kpa).
-> Weigh-foot should rest for at least 2 seconds, but not more than 5 seconds.
With a weight dead micrometer, forensic document examiners can easily determine the bulking thickness. For that, the thickness of stacked 10 sheets is employed.
Quick Note: Torn or partially destroyed document’s surface measurement can be determined using imaging tools such as AutoCAD, ImageJ, Visilog, etc.
4. Paper Density
- Instrument: No required
- Units: kg m−3
- Normal paper Density: around 700 to 800kgm−3
Paper density is governed by the packing and arrangement of pulp while paper production.
The value is obtained by thickness and grammage. However, if the grammage value is missing (torn/partially burnt) still paper density can be calculated, but not practically viable.
How to calculate paper density?
- Weight of sheet in kg.
- Average thickness (µm) of 10-20 measurement points.
- Calculating volume using thickness and converting them into m3
- Paper density= Weight per apparent volume
Example: Find the paper density of a sheet whose thickness is 102µm and grammage value is 75.423 gsm.
- Convert gsm into kg: 75.423gsm= 75.423g per square meter= 75.423 g= 0.075423 kg
- Thickness= 102µm= 0.000102 m
- Apparent Volume= 1 m x 1 m x 0.000102 m= 0.000102 m3
- Paper density= Mass/volume= 0.075423 kg/ 0.000102 m3= 739.44kgm−3
5. Wire and Felt Marks
- Instrument: Alternative Light Source
Wire marks are because of paper being in contact with wire (or forming fabric) during paper manufacturing. While the non-wire side (another side) is called felt.
- Wire marks are common while felt marks are not
- Wire side seems rougher because of the wired pattern
These marks are highly individualistic in a batch of sheets. So, by wire and felt marks, one can define whether two samples are from the same ream (a commercial pack of 500 pages).
But that is not always true.
In many cases, two sheets from the same ream have different wired patterns.
Why? Because five to six different machine rolls that cut sheets simultaneously to produce a single ream. Therefore, you as an examiner should be considered to observe at least six sequential wired patterns to come up with any conclusion.
How to check for Wire and Felt marks on paper?
- Holding the paper horizontally to the surface.
- Use alternative lights, make light strikes over the surface at a low angle, less than 10°.
- Capture images using low magnified microscopy for further analysis of marks distribution.
Observation: Markings appear to be regularly patterned, usually rectangular or diamond-shaped.
Quick Note: Further analysis can be performed by enhancing the captured image. To make it more potent evidence, a fast reverse Fourier transform can be performed to give the wiring pattern.
6. Odor Analysis
Older documents, scent differently. The main cause of these scented hints is the release of Volatile organic compounds (VOCs). Their sources could be of multiple components, including base sheets, coatings, inks, adhesives, etc.
Olfactory Detection Port (ODP) and a Gas Chromatography-Mass Spectrometer (GCMS) to increase our ability to determine the source of odors in a complicated matrix.
To complete the odor analysis, the sample is introduced into the GC for separation and the column effluent is split between the Mass Spectrometer for identification and the Olfactory Port for subjective identification of the odor. This system allows SGS-IPS to separate complicated mixtures and correlate the chemical components to the source of the odor.
C. Watermarks Examination
Watermarks are translucent markings on the paper that defines the origin or company that they are associated with.
Information such as paper origin, authenticity, quality of sheets, and paper dating can be computed using watermark examination.
However, in some cases, depth analysis of watermarks is needed when suspected forgery. You can know more about— How to detect a forgery in Watermark Questioned documents?
Other resources on our Web related to watermarks on questioned documents.
- Watermark Types and their Significance in Forensic Questioned Document Examination
- Watermark Examination of Paper: Tools and Techniques
- Age Estimation of Questioned Document Using Watermarks
D. Pulp And Fiber Analysis of Paper
Paper pulp and fiber analysis is a destructive analysis that can help a forensic expert to identify the composition of different fibers, what the pulping process involves, and finally the origin of the fiber itself.
In general, there are six pulping processes and two major types of fibers.
Two major types of paper fibers that are used for making questioned documents are; Wood fibers (hardwood, softwood) and non-wood fibers.
Six pulping processes include sulfite, Kraft, semi-chemical hardwood pulping, thermo-chemical pulps, and soda pulping.
For the examination of fibers and pulp parts, there are three main procedures;
- Morphological and microscopic analysis: Includes examination of shape, the structure of cells, cross marking on surface, dimension of cells, and their components.
- Chemical Stain analysis: Graff C stain, Wilson stain, and Herzberg stain are majorly employed by forensic document examiners to depict the types of pulping process involved during manufacturing.
- Pulp Fiber Weighting and Composition: The pulp composition and weight can be computed with the help of a multistation tally course (for counting fibers).
All the procedure on how to compute all these three examinations of paper pulp and fiber is explained in the post.
E. Identification of Paper Additives
Papers need additional substances to make a desirable paper and these additional substances are the additives that are added to improve strength, flexibility, decrease absorption rate, optical characteristics, coloration, binding agents, and so on.
They are usually present in the form of starch, protein, waxes, oils, and other fillers and pigments that can be used by the FDE to line down the profile of the specific sheet.
Common paper additives are:
- Sizing Materials: improve strength and flexibility
- Loading Material: improve physical and optical properties
- Coating Materials: make surfaces less absorbent
- Calcium Carbonate: optical brightness agents (OBAs)
- Pigments and Dyes: coloration
- Cationic Retentions: binding dyes and pigments with pulp fiber
- China Clay: smooth and reduce shrinkage
- Titanium Dioxide: white pigment
- Soda Ash: dissolving non-cellulose part of the husk
Continue Reading: Identification of Paper Additives: Fillers, Oil, Waxes, and Pigment
F. Instrumental and Tools Analysis in Paper Forensic
There are a lot of instruments to deal with the questioned documents. Some are listed below:
- Measuring tools: rulers, grids, dead weight thickness micrometer, typewritten measuring plate, weighing machine, etc.
- Magnification Supplements: Handheld, assorted magnifiers, optivisor, comparator, stereoscopic microscope, comparison microscopes, scanning electron microscopes (SEM), etc.
- Special tools to paper forensic: microspectrophotometer, spectrophotofluorometer, Paper Brightness Tester (TAPPI &, ISO), Glossmeter, and Opacimeter.
- Decipherment of Indentation and Secret Writing: Video Spectral Comparator (VSC), Electrostatic Detection Apparatus (ESDA), Raman Spectrometer, Olfactory Port Detector, X-ray Diffraction Techniques, and various other spectroscopy Measuring Instruments in age estimation.
- Documentation and Duplicating devices: DSLR camera, printer, photocopier and scanner.
G. Absolute Age of Documents Using Paper
In some cases, finding the age of paper is required. It gives a relative age when the paper was possibly made.
Finding the age of paper can be easy and difficult too, depending on what type of questioned document is. If a QD sample is a type of security document such as banknotes, it is relatively easy to find the manufacturing date.
If the sample is written on paper, ink analysis works hand in hand to depict when it was first written which may lead to finding a period boundary how old the paper was.
Additionally, watermarks can also provide reliable information on the ages of paper. Paper Dating Using Watermarks: Is It Possible? Let’s Find Out!
However, if the QD sample is nothing but a blank sheet, the examiner has to stretch the examination and comparison to a much larger extent.
You can find the whole list of 11 Forensic Ages Estimation Techniques for Paper Dating
Challenges and Limitations in Forensic Paper Analysis
- Quantitative insufficiency of standard samples
- Deliberate distortion and submission of non-original documents.
- Multiple origins of standard paper samples (printed by different employees by different machines and paper).
- High quality reprinted documents
- The same batch of paper is used for forgery or insertion in multi-paged documents.
- Lack of resources and instrumentation.
- Absolute age is harder to define if the papered document has no writing or markings.
- Improper assessment by forensic document examiner.
- Latent prints, DNA, etc can be results of earlier storage, handling, testing.
- Excessive handling during collection and storage can flatten the impressions.
- Water-soaked, soiled, burnt, or finely shredded paper may make it inappropriate for some examinations.