This color contains the following pigments:
charred animal bone
carbon + calcium phosphate
C + Ca3(PO4)2 or C x CaPO4
Ivory Black is a cool, semi-transparent blue-black with a slight brownish undertone and average tinting strength. It mixes well with any color, and creates a range of dull greens when mixed with yellow. It has good properties for use in oil, can be slow to dry in oil form, and should never be used in underpainting or frescoing. Ivory Black is denser than Lamp Black.
Ivory Black is very lightfast and has good permanence, though it is considered the least permanent of the major black pigments.
Ivory Black has no significant hazards.
Ivory Black is a carbon based black first named as Elephantium, and described in the 4th century BCE as produced by heating ivory scraps in clay pots to reduce the ivory or bone to charcoal. The deviation in names is because the more expensive varieties of this pigment were made by burning ivory, and the less expensive ones by burning animal bone. In the 19th century, the name Ivory Black was finally permitted to be applied to Carbon Black pigments made from bone. True Ivory Black is rare in modern times due to the protection of ivory, and the synthetic variety produced today was discovered in 1929. Bone Black is produced as an industrial pigment.
Sepia is a rich, dark reddish brown pigment that can be dull in heavy applications.
Natural sepia has fair lightastness. Modern synthetic pigments that have been developed to replace cuttlefish ink are considered superior.
Sepia is not considered toxic. Cuttlefish are caught for food throughout the Mediterranean region and East Asia. The dye is often used as a natural food colorant.
Sepia was originally derived from the ink sac of the cuttlefish (Sepia officinalis), found in Mediterranean waters. Methods for extracting this natural ink and turning it into a concentrated pigment became common in the early 19th century. Today the color name is usually applied to more lightfast synthetic pigments, and the natural pigment is rare. The ink was used to color early black-and-white photographs. The name sepia has endured as a synonym for photographs colored by this process, and even for modern digital photos that are converted to sepia tones.