Paint analysis

Forensic Examination of Glass and Paint analysis and interpretation... 

Paint analysis for elements such as Fe in the case of TiC>2 based materials is often important. Also elements such as Cr and Hg may have to be determined. 

The main emphasis in forensic paint analysis lies in the comparison of materials the physical and... 

Concerning the paint analysis, reproducible and correct measurements can only be achieved if the sample material is optimally prepared. In the preparation of paint traces it is essential that characteristic features such as common broken edges, striation marks, or texture effects on the upper or lower surfaces are not destroyed. 

For paint analysis, a spectral range comprising between 4000 and 600 cm is usually used, but for the identification of some inorganic pigments and extenders (e.g., titanium dioxide), a lower frequency... 

The main emphasis of paint analysis with SEM concerns EDS or EDX. To compensate for inhomogeneities, the scanned sample areas should be as large as possible. At least two to three areas must be analyzed under standardized measurement conditions. Mapping procedures are recommended for the analysis of cross-sections. In this manner the thinnest layers on the upper and lower surfaces (e.g., zinc phosphate layers on the lower surface of vehicle paint fragments) can be described and analyzed. Metallic paints should be examined at higher magnification (10000 x) in aluminum-free areas. 

An interesting procedure in forensic paint analysis, however, is thermogravimetry-mass spectrometry (TG-MS), determining simultaneously TG curve and its first derivative, total ion current versus the TG temperature, single ion currents for selected molecular fragments versus TG temperature, and determination of the pigment/volume concentration of... 

Caddy B (ed.) (2001) Forensic Examination of Glass and Paint - Analysis and Interpretation. New York Taylor and Francis. 

Scientific Working Group on Materials Analysis (SWG-MAT) (1999) Forensic paint analysis and comparison guidelines. Forensic Science Communications, U.S. Department of Justice, FBI, July 1999, vol. 1(2). Online www.f bi. gov/progra ms/la b/f sc/backissu/julyl999/painta. htm. 

Among techniques employed in paint analysis, spectrophotometric methods (infrared (IR), Raman, and UV-visible), chromatography (both gas and liquid). X-ray diffraction and fluorescence, atomic spectrometry, nuclear magnetic resonance, and pyrolysis are the most useful and provide more selective or more sensitive information than the classical procedures about the main components of paints. In the following sections the main merits and applications of these techniques will be described. 

Liquid chromatography (LC) can effectively replace GC in the analysis of paint components with low volatility. Among LC techniques the most interesting in paint analysis is gel permeation chromatography (GPC), which provides an interesting tool for the characterization of binders from the study of the composition and molecular mass distribution of the resins. 

Forensic science makes nse of IR spectroscopy and IR microscopy, not only for paint analysis but for analysis of controlled snbstances. IR can be used to detect the active compounds in hallucinogenic mushrooms, for example. IR is often used to confirm the identity of controlled substances such as cocaine. It has the advantage of being able to differentiate isomers that cannot be distinguished by mass spectrometry (MS), for example, ephedrine and pseudoephedrine. 

Standard Guide for Forensic Paint Analysis and Comparison. ASTM Standards, Designation E 1610-95 ASTM Philadelphia, PA, 1995. 

Standard Guide for Forensic Paint Analysis and Comparison," in ASTM Standard E1610-02 14.02, ed. ASTM Intematioiial, 2004. Thornton,., "Ch. 8 Forensic Paint Examination," in Forensic Science Handbook, Volume II, R. Saferstein, ed., 2d ed. Upper Saddle River, NJ Prentice Flail, 2002. 

Mass spectrometry using alternative ionization and sample preparation methods are employed in ink and paint analysis. The oldest of these techniques is based on pjnrolysis of the sample (typically, a paint) prior to its introduction into the GC. Detectors for PyGC are and FID. Pyrolysis patterns can be examined in the same way accelerant patterns are (Chapter 10), but increasingly, GCMS is preferred over FID. Pyrolysis is, by definition, destructive, but the sample size is reasonably small, and recently a micropyrolysis GCMS has been developed and applied to photocopier toners and paint. A laser is focused on the sample through a microscope, and the pyrolysis vapor product is directed into the GCMS system. The pattern of the pyrolyzates and chemical composition... 

Takami, M. and Eastop, D. (2002). The conservation of a Korean painted silk banner, c. 1800 paint analysis and support via solvent-reactivated acrylic adhesive. In R. Vontobel (Ed.), 13th triennial meeting, Rio de Janeiro, 22-27 September 2002 Preprints 747-754, James James. 

Hameau et aL (2001) Hameau, P Cruz, V Laval, E. Menu, M. Vignaud, C. Paint analysis of some post-glacial sites in southeastern YrnDcC Anthropoloffe 105 (2001) 611-626 Hansen Brownmii.ler (1928) Hansen Brownmiller American Journal of Science CCXV (1928) 229 Hanzel et oL (1990) Hanzel, D. Meisel, W Hanzel, D. Giithch, P. Mossbauer effect study of the oxidation of vivianite Solid State Communications 76 (1990) 307-310 Harborne Baxter (1999) Harbome, J.B. Baxter, H. The Handbook of Natural Flavonoids 2 vols., John Wiley Sons, Chichester, UK (1999)... 

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