Creating A Colourful Life

Red

On this page is information about red colours. These are:

Vermilion Cinnabar
Pink Madder / Rose Madder
Light Red / Venetian Red
Cochineal Lakes
Red Lead
Cadmium Red
Litharge
Realgar

Vermilion Cinnabar

Use - Paint pigment

Formula - HgS

Chemical Name - Mercuric sulfide

Structure - Hexagonal

Synthesis - Mix mercury and sulfur until combined. Sublime and condense. Powder, grind and moisten the product with water, followed by warm water containing nitric acid.

Interesting Facts - Used in the wall paintings of Pompeii.

Pink Madder / Rose Madder

Use - Paint pigment

Formula - n/a

Chemical Name - n/a

Structure - n/a

Synthesis - Manufactured from anthrocene found in cool tar.

Interesting Facts - Was used in the 14^th century, when it was made from the root of the madder plant native to Greece. The root was dried, ground and treated with sulfuric acid, filtered and washed with water.

Light Red / Venetian Red

Use - Paint pigment

Formula - Fe₂O₃

Chemical Name - Iron(III) oxide

Structure - Rhombohedral

Synthesis - Heat yellow ochre (iron(III) oxide monohydrate) to drive off its associated water. Alternatively grind the red hematite mineral.

Interesting Facts - Used in cave paintings as well as by the Egyptians, Ancient Greeks and Romans.

Cochineal Lakes

Use - Paint pigment

Formula - n/a

Chemical Name - n/a

Structure - n/a

Synthesis - Grind dried Cochineal beetles, boil in water for several weeks and treat with dilute sulfuric acid.

Interesting Facts - Was used as a food colouring since Victorian times. Made from dry, wingless female Cochineal beetles. Carminic acid gives the red colour and is hyrolysed by dilute sulfuric acid to give armine red and sugar. It was colour additive E120. In the pictures the far right depicts dried cochineal beetles, and the near right depicts modern synthetic carmine.