DECAY OF EMERALD GREEN PIGMENTS ON EASEL PAINTINGS

Abstract

Emerald green is one of the pigment  of its composition arsenic, copper It is usually used in coloring the areas of trees and clothing, the color by ageing and exposure to inappropriate environmental conditions (temperature, humidity, and ultraviolet) turn Dark brown color caused of  changing chemical and structural composition of the paint layer, The changing in colored is not only from medium damage, but there are factors that play an auxiliary role with medium damage, The  medium is decomposed and free fatty acids interact with metal ions in emerald green, which leads to the formation of mineral soap that leads to the instability of color particles , the loss of contact between of  them it  ,decompose it  and forms a decomposition product of arsenic trioxide(As₂O₃), Which migrates on the surface and interacts with pollutants and discolored green. This article aims to study of the phenomenon of emerald green color change on an oil painting from the 19th century in Al Jazeera museum by the French artist Ad.Monticelli (1824-1886), using an examination by Micro scope  Om ,   PLM ,analysis FTIR , XRD ,and SEM-EDX,. The Analytical XRD analysis showed that the archaeological color sample from emerald green, which has different mineral forms of arsenic damage, such as Copper hydrogen AsCuHO₃, lead Arsenite [Pb₂As₂O₅], and Clinoclase [Cu₃AsO₄(OH)₃] is a mineral water arsenic copper and Arsenicsulfide As₂S₃ ,FTIR study showed the decomposition products of emerald green, as monocarboxylate, calcium oxalate salts, and arsenic trioxide [As₂O₃].