This volume presents the life work of the late Ruth Johnston-Feller, one of the nation's leading color scientists. It combines an overview of basic theoretical concepts with detailed, hands-on guidance for the professional conservator and conservation scientist. The author focuses on the application of color science to the solution of practical problems, providing a comprehensive discussion of the nondestructive spectrophotometric tools and techniques used to understand the color and appearance of materials during the technical examination of works of art. The book, which features numerous examples of reference reflectance spectra, can help prevent misinterpretation of color measurements and the erroneous conclusions that might result. Topics include spectrophotometry, colorimetry, colorant mixtures, analytical techniques, reflection, fluorescence, and the effects of extenders, fillers, and inerts.