Pb3O4

Pb3O4, commonly known as red lead or minium, is a mixed-valence oxide of lead with the formula Pb3O4. It can be viewed as 2 PbO·PbO2, containing lead in both +2 and +4 oxidation states. The compound forms bright red to orange-red crystalline powders and has long been used as a pigment and drying agent in paints.

Production and properties: Red lead is typically produced by heating lead(II) oxide in air, which induces partial oxidation to the PbO2 component. It is insoluble in water and relatively stable under ordinary environmental conditions. It can react with strong acids to form soluble lead salts, and it may decompose under high temperatures or reducing conditions.

Uses: Historically, red lead served as a durable and vibrant pigment for oil-based paints. It also functioned as a drying or siccative agent in linseed oil paints, helping the film to cure. In addition, it has been employed as a primer for metal surfaces to promote adhesion and corrosion resistance, though its toxicity limits its modern use in some applications.

Safety and hazards: Lead compounds, including Pb3O4, are toxic if inhaled or ingested and can cause lead poisoning. Handling should follow strict safety protocols, including appropriate containment, respiratory protection when dust is generated, and proper disposal of waste. As with many lead materials, usage is increasingly restricted or replaced in consumer products due to health and environmental concerns.