Current Names: English: King's Yellow (artificial); German: Rauschgelb, Operment; French: orpiment; Spanish: oropimente; Italian: orpimento Obsolete Names: auripigmentum The modern name comes from the Latin auripigmentum, or golden pigment. Color: Yellow Green Colour Index: Pigment Yellow 39 Density: 3.5 Hardness: 1.5 Chemical Formula: As2S3
Orpiment is yellow arsenic sulfide, usually described as a lemon or canary yellow or sometimes as a golden or brownish yellow. It is designated as brilliant yellow in Munsell notation 4.4Y 8.7/8.9. Orpiment is a rare mineral that usually forms with realgar. In fact the two minerals are almost always together. Our orpiment is from Kadamdzhay in Kyrgyzstan.
History of Use: It is an historical pigment having been identified on ancient Egyptian objects and paintings from the thirty-first to the sixth century B.C. It is mentioned in Greek and Roman literary sources. The Hellenistic Leyden papyrus described its use for late Egyptian painting, as does the Mappae Clavicula for early mediaeval painting. The pigment has been described in various other mediaeval manuscripts dating from the 12th to the 15th centuries.
Permanence and Compatibility: Early authorities usually described orpiment as fading readily, or at least to some degree on exposure to light. It is said to be incompatible with lead- or copper-containing pigments. Molart studied the mechanisms of deterioration in orpiment. Several medieval painting guides do not recommend mixing orpiment with lead white, red lead or verdigris. However, it must also be noted that it has been identified in paintings mixed with indigo, red iron oxide, azurite, Prussian blue, green bice (artificial malachite), and bice (smalt). It cannot be applied to wet plaster, and hence is not recommended in wet fresco painting techniques.
Oil Absorption and Grinding: No data has been published on the oil absorption properties of orpiment. It is difficult to grind because of its micaceous structure. For this reason, it is often quite coarse. It has been suggested to add ground glass to the pigment to facilitate grinding and dispersion in linseed oil.
Toxicity: The toxicity of arsenic sulfide pigments has been known for years. Extreme caution must be used when handling the dry orpiment pigment, as well as in any soluble form, to avoid inhaling the dust or ingesting it.
NOT FOR HOME USE. SOLD ONLY TO PROFESSIONALS. Read cautions about handling pigments