Orange
On this page is information about orange colours. These are:
Realgar
Use - Paint pigment
Formula - As4S4
Chemical Name - Arsenic sulfide
Structure - Monoclinic
Synthesis - Realgar mineral
Interesting Facts - Was used as a rat poison. Realgar has also been used in China to make into ornaments that ward off evil spirits.
Chrome Orange
Use - Paint pigment
Formula - PbCrO4 • Pb(OH)2
Chemical Name - Basic lead(II) chromate
Structure - Monoclinic
Synthesis - Lead nitrate and potassium dichromate are dissolved in seperate portions of hot water (100ml). Sodium hydroxide is added to the dichrmoate solution before the solutions are mixed. The precipitate is washed and then dried at 500°C.
Interesting Facts - Readily faded by light, modern varieties of this pigment are photochemically stabilised.
Henna / Lawsome
Use - Dye
Formula - C10H6O3
Chemical Name - 2-hydroxy-1,4-napthoquinone
Structure - n/a
Synthesis - Dry, grind and then sift powdered leaves from the Henna plant.
Interesting Facts -
Saffron
Use - Paint pigment
Formula - C16H26O7
Chemical Name - 4-(β-D-glucopyranosyloxy)-2,6,6-trimethylcyclohex-1-ene-1-carboxyaldehdye
Structure - n/a
Synthesis - Made from dried stigmas of the Saffron crocus flow.
Interesting Facts - Has been found present in 50 000 year old pigments in Iraq.
