Infrared Analysis of Paint Samples

Infrared spectroscopy can also be used to identify generic paint types as these also have distinct infrared spectra. This information may be required for the purpose of over painting with a compatible paint system, selecting a suitable paint stripper to remove multiple layer paint systems or for the purposes of obtaining data for historical records. Due to the requirement of a small sample size, individual layers of paint can be analysed using infrared spectroscopy within a multiple layered paint system, provided they can be separated. As in the case of sealants the instrument is capable of detecting very slight differences between resins and figure 3 shows the infrared spectra of alkyd resins variously modified.

Figure 3 Infrared spectra of modified alkyd resins in paint samples.

Infrared spectroscopy is also sensitive enough to detect the difference between paint application methods, and Figure 4 shows the infrared spectra obtained for a sprayed and a powder coated polyester resin paint finish.

Figure 4: Infrared spectra of polyester resin paint finishes.