Yellow

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

• Yellow Ochre
• Cadmium Yellow / Aurora Yellow
• Aureolin / Cobalt Yellow
• Lemon Yellow / Yellow Ultramarine
• Indian Yellow / Piuri
• Mars Yellow / Artificial Ochre
• Naples Yellow
• Yellow Lake / Yellow Madder
• Chrome Yellow
• Orpiment
• Nickel Titanate

Yellow Ochre

Use - Paint pigment

Formula - Fe₂O₃ • H₂O

Chemical Name - Iron(III) oxide monohydrate

Structure - Orthomrhombic

Synthesis - Reacting iron salts and metallic zinc

Interesting Facts - Used by the Egyptians, Ancient Greeks and Romans. Pots of iron oxide were found at pompeii. Can be used to make brown ochre by heating with sodium chloride.

Back to top

Cadmium Yellow / Aurora Yellow

Use - Paint Pigment

Formula - CdS

Chemical Name - Cadmium sulfide

Structure - n/a

Synthesis - mix cadmium chloride or sulfate and sodium sulfide or alternatively heat cadmium oxide in presence of excess sulfur and wash with distilled water.

Interesting Facts

Back to top

Aureolin / Cobalt Yellow

Use - Paint pigment

Formula - K₆Co₂(NO₂)₁₂ • 3H₂O + K₆Co₂(NO₂)₂

Chemical Name - n/a

Structure - Cubic

Synthesis - Prepared from potassium and cobalt nitrites. The anhydrous product is formed by reacting with concentrated acetic acid.

Interesting Facts - n/a

Back to top

Lemon Yellow / Yellow Ultramarine

Use - Paint pigment

Formula - BaCrO₄

Chemical Name - Barium chromium oxide

Structure - Orthorhombic

Synthesis - Mix hot, aqueous solutions of potassium chromate and barium chloride. The dried product is then ground.

Interesting Facts - Strontium chromium oxide is often used instead, but is less stable. The mineral name is Hashemite.

Back to top

Indian Yellow / Piuri

Use - Paint pigment

Formula - C₁₉H₆MgO₁₁ • 5H₂O

Chemical Name

Structure

Synthesis - dry the urine of cows fed on mango leaves.

Interesting Facts - said to have an evil smell.

Back to top

Mars Yellow / Artificial Ochre

Use - Paint pigment

Formula - Fe(OH)₃ or Fe₂(OH)₂

Chemical Name - Iron hydroxide

Structure - Cubic

Synthesis - React iron sulfate/chloride with sodium hydroxide. Dry the precipite in air.

Interesting Facts - different shades can be created by heating to different temperatures.

Back to top

Naples Yellow / Yellow Madder

Use - Paint pigment

Formula - Pb₂Sb₂O₇

Chemical Name - Lead antimony oxide

Structure - Cubic

Synthesis - Heat 1 part antimony potassium tartarate (C₄H₄KO₇Sb) with 2 parts lead nitrate and 4 parts sodium chloride for 2 hours.

Interesting Facts - Found on 2500 year old Babylonian bricks.

Back to top

Yellow Lake / Yellow Madder

Use - Paint pigment

Formula - n/a

Chemical Name - n/a

Structure - n/a

Synthesis - Grind American oak tree bark to a powder and place in hot water. yellow colour occurs when alum and dilute ammonia are added. A more vivid colour can be obtained by using sulfuric acid instead of water.

Interesting Facts - bark comes from the Quercus tinctoria and two other American oak trees.

Back to top

Chrome Yellow

Use - Paint pigment

Formula - PbCrO₄

Chemical Name - Lead chromate

Structure - Monoclinic

Synthesis - Mix hot aqueous solutions of lead nitrate and potassium dichromate.

Interesting Facts - n/a

Back to top

Orpiment

Use - Paint pigment

Formula - As₂S₃

Chemical Name - Arsenic sulfide

Structure - Monoclinic

Synthesis - Mined from orpiment mineral

Interesting Facts - Was used as a medicine in China even though it is toxic! It was also used as a fly poison and to poison arrows.

Back to top

Nickel Titanate

Use - Paint pigment

Formula - NiTiO₃

Chemical Name - Nickel titanate

Structure - Rhombohedral

Synthesis - Heat a mixture of nickel and titania powders at 1000°C for 48 hours. Compress into 100g pellets and fire at 1300°C for 2 hours.

Interesting Facts - n/a

Back to top