Paint One of the most common types of paint examined in the crime laboratory involves finishes emanating from automobiles. Paint spread onto a surface will dry into a hard film that can best be described as consisting of pigments and additives suspended in the binder.

Paint The elements that are contained within paint pigments can be identified by emission spectroscopy or X-ray spectroscopy. Emission spectroscopy collects and measures the various light energies given off by the atom. Crime laboratories are often asked to identify the make and model of a car from a small amount of paint and will make use of color charts for automobile finishes or the PDQ database.

Paint Pigments and Dyes traditional pigments are derived from finely ground minerals or inorganic compounds. Most dyes came from organic sources such as berries and insect bodies. Many colored synthetic organic and inorganic compounds are now available. Upon Drying - solvent and/or binder transforms into a crosslinked solid by oxydation in air (Oil paints). Other binders crosslink by radical polymerisation mechanisms (e.g. UV curing) or isocyanate reacting with hydroxyl groups to form urethane.

Paint Chips Paint chips- individualized to a single source by examining color and layer structure Pyrolysis gas chromatography- compares the polymeric make-up of paint binders Automobile finishes- contain an electrocoat, primers, colorcoat and clearcoat Layers determined by microscopy and spectroscopy.

Paint chips are most likely found on or near persons or objects involved in hit-and-run incidents. Paper druggist folds and glass or plastic vials make excellent containers for paint. Paint smeared or embedded in garments or objects require the whole item to be packaged and sent to the laboratory. Uncontaminated standard/reference paint must always be collected. Tools used to gain entry into buildings or safes often contain traces of paint, requiring the tool be collected, along with reference paint samples.

Paint Analysis Lincolnshire, UK - 1991-1993, two murders by axe. Imprint of axe found on sofa and pillows. Axe found in local pond and paint analysis by ICP-AES. Matches paint at crime scene. Axe shape matches patterns found on sofa. www.lincoln.ac.uk/fabs/archives/Odontology/TheLncshrAxeMurd.htm

Proper collection and preservation of paint evidence from an automobile suspected of being involved in hit-and-run incident. Paint that is foreign to the suspect automobile is observed on the hood. Scrape the foreign paint as well as all underlying layers of paint off the car’s surface using a clean knife or scalpel. The scraping must clearly show the layer structure of the paint. Obtain a control paint sample from an adjacent undamaged area of the car. Again, all layers must be included. Package each paint specimen separately in a proper container. A druggist fold or a vial makes an excellent container. Label all specimen containers. Evidence collector’s name or initials, the date, and the sampling location are to be shown. All items collected are to be described in the evidence collector’s field notes.