Technical Note
Survivability of Latent Fingerprints
Part II: The Effect of Cleaning Agents on
the Survivability of Latent Fingerprints
Yaron Cohen
Myriam Azoury
Michal Levin Elad
Latent Fingerprint Laboratory
Division of Identification and Forensic Science (DIFS)
Israel Police, National Headquarters
Jerusalem, Israel
Abstract: The present work reports the results of experiments carried out to evaluate the effectiveness of some common commercial
cleaning products on the survivability of latent fingerprints on smooth
surfaces. This work disputes the assumption that latent fingerprints
do not survive cleaning agents.
Introduction
In the f irst part of the study [1], we observed high aff inity of latent f inger prints to some smooth surfaces, such as
powder-coated aluminum window frames and PVC shutters. The
fingerprints strongly adhered to the surface and resisted brushing, scratching, and finger smearing. The fact that the college
discussed in Part I was uninhabited led to another question that
will be explored in this part of the work: can latent fingerprints
on smooth surfaces survive commercial cleaning agents?
Received March 30, 2010; accepted July 21, 2010
Journal of Forensic Identification
54 / 62 (1), 2012
The resistance of latent fingerprints to cleaning agents is a
frequent issue raised in court. There is a common belief that the
cleaning process wipes prints from the surface. As the following
citation reveals: “... if it can be shown that a particular surface
is thoroughly cleaned at least once a week, then a mark found on
that surface could not be more than a week old.” [2]
This present work reports the results of experiments carried
out to evaluate the effect of some common commercial cleaning
products on the survivability of latent fingerprints on smooth
surfaces.
Materials and Methods
Clean, nonporous surfaces were used: PVC window shutters
and powder-coated aluminum window frames.
Sebaceous f inger prints were obtained from donors after
wiping their fingers across oily regions (forehead, nose, neck,
or hair).
Finger prints were developed with black magnetic powder
(Lightning Powder Company, Inc., Jacksonville, FL).
The following cleaning products were used:
Windolene Glass Cleaner (Reckitt Benckiser, England)
Ajax Window Cleaner (Colgate Palmolive-Hellas,
Geneva, Switzerland)
Sanoclear (Sano-Bruno’s Ltd., Israel)
Aston ish Bat h room Clea ner (T he Oil Ref i n i ng
Company Ltd., Pudsey, U.K.)
Astonish Glass & Tile Cleaner (The Oil Ref ining
Company Ltd., Pudsey, U.K.)
Astonish Kitchen Cleaner (The Oil Refining Company
Ltd., Pudsey, U.K.)
One set of fingerprints was deposited on the surfaces and
left overnight before processing. Another set of fingerprints was
deposited and left for two months before processing. The surfaces
were kept in ambient room temperature after deposition. Each
set contained five donors who donated two fingerprints each.
Each set of f inger prints was developed with black magnetic
powder after one day or two months. The latent prints were
then washed and wiped with cotton cloth using the cleaning
liquids mentioned. After cleaning and drying, the surfaces were
processed again for fingerprints.
Journal of Forensic Identification
62 (1), 2012 \ 55
Results
As seen in Table 1, the results show that most of the cleaning
products used in this experiment did not remove fingerprints
either from the white aluminum frame or from the PVC window
shutter surfaces. The sebaceous fingerprints adhered to these
surfaces and could be developed even after the use of cleaning
agents (Figures 1 and 2). The same results were observed for
fingerprints deposited one day or two months before the initial
development with black magnetic powder.
Commercial Cleaning
Agent
“cleans windows and
surfaces”
Windolene
Ajax Window Cleaner
Information on
Ingredients
[CAS No.]
Manufacturers’ Claim
“for window cleaning”
Butoxypropanol<5%
[5131-66-8] Sodium
Hydroxide<1% [131073-2] [3]
Fingerprints Fingerprints
remain
remain
Wetting agents
Oxygenated solvents [4]
Fingerprints Fingerprints
remain
remain
“cleans windows and hard N/A
surfaces”
Sanoclear
Astonish Bathroom
Cleaner
Astonish Glass & Tile
Cleaner
Astonish Kitchen Cleaner
WhitePVC
coated
Window Aluminum
Shutter
Frame
Fingerprints Fingerprints
remain
remain
“cleans, glosses and
removes mineral
deposits”
2-(2-butoxyethoxy)
ethanol 1–5% [112-34-5]
Nonionic surfactant<1%
[68439-46-3]
Nonionic Sufactant<1%
[8051-30-7] [5]
Fingerprints Fingerprints
removed
remain
“for glass, painted
surfaces, plastic”
Propan-2-ol 1-5%
2-(2-butoxyethoxy)
ethanol 1-5% [112-34-5]
Anionic surfactant<1%
[9004-2-] [5]
Fingerprints Fingerprints
remain
remain
“for greasy surfaces”
2-(2-butoxyethoxy)
ethanol 1-5% [112-34-5]
Fingerprints Fingerprints
Nonionic surfactant<1-5% removed removed
[68439-46-3] [5]
Table 1
Fingerprint survivability after using cleaning agents.
Journal of Forensic Identification
56 / 62 (1), 2012
Figure 1
Fingerprints on PVC shutter after cleaning with Windolene.
Figure 2
Fingerprint on coated aluminum window frame after cleaning with
Windolene.
Journal of Forensic Identification
62 (1), 2012 \ 57
Discussion
In order to understand these results, we investigated the
surface properties of the sebaceous fingerprints and the properties of the cleaning products.
Sebaceous f inger prints exhibit a strong adherence to the
surfaces examined, which might be related to their “contact
angle”. Contact angles for f inger prints are very low (0 –30°)
and contact angles for sebum-rich fingerprints are even lower
(0–12°) [6]. However, the distribution of contact angles is more
or less independent on the surface energy of the surface on which
they are deposited, according to Thomas et al. [7, 8]. This led us
to believe that this is the explanation for their strong adherence
to the surfaces. Zisman notes that long-chain fatty acids and
alcohols adhere to surfaces such as glass and metal and form a
close, packed monolayer [9]. This may happen with sebaceous
fingerprints and thus supports this thesis.
The cleaning products – surface-active materials (surfactants) – are composed of molecules containing both polar and
nonpolar parts. The hydrophilic part of most effective soluble
surfactants is often an ionic group. Ions are hydrophilic in nature
because of the electrostatic attraction to the water dipoles and
therefore are capable of pulling fairly long hydrocarbon chains
into solution. Surfactants may have nonionic hydrophilic groups
that also exhibit a strong affinity to water. For example, the
monomer unit in a poly(ethylene oxide) chain shows a modest
affinity for water but the sum effect of several of those units
in a polymer chain is an overall strong affinity for water [10].
If a f luid is strongly attracted (good adherence) to a solid
surface, the contact angle will be small. However, if the wetting
is unfavorable, the f luid will form a compact droplet on the
surface (Figure 3).
Water repellency is an important characteristic of window
cleaning products. This property allows the quick drying of the
cleaning product on the surface, and, therefore, thorough cleaning is achieved. The repellency is achieved by adding agents
that increase the contact angle such as dimethyldichlorosilane,
which is a good hydrophobic agent for silica and glass surfaces.
The dimethyldichlorosilane reacts with the –OH groups of the
silicate lattice with the elimination of HCl to give the structure
as seen in Figure 4.
Journal of Forensic Identification
58 / 62 (1), 2012
As seen in Table 1, most of the commercial window cleaning
products used in the present study were water-based with water
repellant agents (for quick drying) and with low content of detergents. The cleaning products that removed fingerprints were
Astonish Kitchen Cleaner (PVC shutters and aluminum frame)
and Astonish Bathroom Cleaner (PVC shutters). Therefore, it
seems that the concentration in the cleaning agent is a major
factor when considering the ability to remove the sebaceous
fingerprints that are “fixed” to the surface.
Figure 3
Contact angle as influenced by good and poor adherence.
Figure 4
Hydrophobic glass surface.
Journal of Forensic Identification
62 (1), 2012 \ 59
Conclusion
This part of the study shows that under certain conditions,
f inger prints can remain on surfaces even af ter the use of
commercial cleaning materials. Different commercial products
were investigated, and only two removed fingerprints. In view
of the wide variety of possible substrates, fingerprint constituents, contaminations, and the variety of cleaning reagents, we
summarize by disputing the assumption that cleaning agents
really clean various surfaces. However, the detergent concentration should be considered when this question is discussed
in courts, and one should not always assume that the use of a
cleaning product leads to fingerprint removal. In view of this
study, we recommend that when this and similar questions are
discussed, a simulation to real conditions be performed and only
then may a final conclusion be given.
For more information, please contact:
Michal Levin Elad
National Headquarters
Hainm Bar-Lev Road
Jerusalem 91906
[email protected]
References
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Elad, M. L. Survivability of Latent Finger prints, Part 1:
Adhesion of Latent Fingerprints to Smooth Surfaces. J. For.
Ident. 2012, 62 (1), 47–53.
2. Champod , C.; Len na rd , C.; Ma rgot, P.; Stoilovic, M.
Fingerprints and Other Ridge Skin Impressions; CRC Press:
Boca Raton,FL, 2004; p 193.
3. Reckitt Benckiser, Material Safety Data Sheet - Windolene,
Glass Cleaner. Berkshire, U.K.
4. Colgate -Palmolive, Ltd. Material Safety Data Sheet - Ajax
Window Cleaner, Liquid. Guildfords Surrey, U.K.
5. Astonish House. Material Safet y Data Sheet- Astonish
Bathroom Cleaner. Leeds U.K. http://www.astonishcleaners.
com/documents/document-astonish-HWhA4.pdf (accessed
September 15, 2009)
6. Scr uton, B.; Robins, B. W.; Blott, B. H. The Deposition
of Fingerprint Films. J. Phys. D: Appl. Phys. 1975, 8 (6),
714–723.
7. Thomas, G. L.; Reynoldson, T. E. Some Observations on
Fingerprint Deposits. J. Phys. D: Appl. Phys. 1975, 8 (6),
724.
Journal of Forensic Identification
60 / 62 (1), 2012
8.
T homas, G. L. T he Physics of Finger pr ints and T heir
Detection. J. Phys. E: Sci. Instrum. 1978, 11 (8), 722–731.
9. Zisman, W. A. Relation of the Equilibrium Contact Angle to
Liquid and Solid Constitution. In Contact Angle, Wettability,
and Adhesion. Fowkes, F., Ed.; American Chemical Society:
Washington, DC, 1964; 1–51.
10. Shaw, D. J. Introduction to Colloid and Surface Chemistry,
4th ed.; Butterworth-Heinemann, London, 1992.
Journal of Forensic Identification
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