Seeing Color: Practical Methods in Pigment Microscopy
THE MICROSCOPE
2014, Volume 62:2, pp. 51–61
DOI
https://doi.org/10.59082/OYBV5579
AUTHORS
Christopher S. Palenik and Skip Palenik
ABSTRACT
Microscopical methods permit the pigment particles responsible for color and effects in paints, inks, polymers, rubbers and cosmetics to be directly and readily observed, both in situ and ex situ. Using examples of pigments in paint, fibers and cosmetics, this research will demonstrate practical sample preparation and imaging methods that permit detailed visualization and utilization of pigments as evidence in forensic and industrial examinations. Preparation methods covered here range from the efficient (smears) to the traditional (cross sections) to the state of the art (ion-polished cross sections), while imaging methods spanning length scales of millimeters to nanometers, which include polarized (PLM) and oil immersion light microscopy as well as scanning (SEM) and transmission electron microscopy (TEM) will be demonstrated. Not only does such analytical information provide for the opportunity to make observations impossible by more routine, indirect forensic approaches (such as paint comparisons by infrared spectroscopy) or the casual application of magnification that is common in many laboratories (e.g., stereomicroscopy of paint chips to determine layer structures), but it opens the possibility to find true differences in the finest components of materials, which may be suggestive of a specific manufacturer, batch difference or quality issue. Finally, the resulting images provide a simple and visually compelling means by which to convey such