An experimental campaign took place between 2004 and 2006 in Alentejo in order to identify the pigments used in the traditional limewash and analyze pictorial techniques. The samples were collected in the exterior finishes of buildings localized in the historical centers of 47 municipalities (distributed among the districts of Évora, Beja, Portalegre and Setúbal). Its analysis was based on microchemical tests, supplemented with optical microscopic observations, Fourier transformed infrared spectroscopy and X-ray diffractometry. Results show that, contrary to the present, red pigments based on Fe (III) compounds were predominant in the lime palette of Alentejo and reveal several technical details such as the mixes between several pigments and the use of chromatic layers of variable thickness, that, in many cases, are very different from the system of transparent glazes.