The Minimalist work of Donald Judd exemplifies modern and contemporary works of art that utilize the appearance of bare metal as an integral component of the artist's intent. Decades after fabrication, disfiguring patterns have appeared on the surfaces of many such works. These patterns are not related to the formation of tarnish or other corrosion effects caused by improper storage, display, or transportation and handling; rather, they are associated with the initial processing of the metal sheets and subsequent fabrication of the art objects. Due to the challenges of obtaining analytical data directly from works of art, the authors present results from industrial sheet metal coupons prepared to simulate materials and techniques used in Donald Judd's copper and brass artworks. Attenuated total reflectance Fourier transform infrared spectroscopy carried out on each side of 55 coupons indicated the presence of organic materials such as long-chain aliphatic hydrocarbons, esters, and ethers, consistent with the types of compounds used in industrial lubricants. In addition to conducting the first systematic instrumental analysis of these residues, the authors propose the use of specific solvents for their removal as an alternative to abrasive methods, which cause removal of original surface from the objects.