Analysis by the Analytical Research Services (ARS) of the Canadian Conservation Institute (CCI) often involves light microscopy combined with the scanning electron microscope (SEM). CCI's model incorporates a secondary electron detector, a back- scattered electron detector, and an x-ray detector and spectrometer, with modifications which include digital imaging processing and video microscopy. SEM is extremely useful in conservation and archaeological science. There can be up to 30 layers of paint, corrosion products, dirt, and pollution products, of widely ranging particle sizes, and a variety of materials (which can themselves vary according to source). This versatile instrument is similar to the electron microprobe: both combine electron optics with x-ray spectrometry. A beam of energetic electrons is focused on the surface, at a point, or is scanned over a rectangular area. At each point, there can be emissions of electrons, photons, and x- rays. There is a relationship (Moseley's law) between x-ray wavelengths and the atomic number of the element concerned. The article describes three applications: detection of emerald green in Dégas pastels, detailed analysis of materials used by artist David Milne, and deposits on Canadian rock-painting sites. (Photographs and diagrams are included). -- SCMRE