Toluidine Blue

Toluidine blue

Toluidine blue is an organic dye that is often used to dye cotton and wool fabrics blue. It was first synthesized in 1865 by German chemist Heinrich Caro.

Chemically, toluidine blue is a salt of toluidine and a sulfonic acid and has the formula C15H16ClN3S. It forms a dark blue crystalline powder that dissolves well in water and forms bright blue solutions.

Toluidine blue has high light fastness and is wash and abrasion resistant. Therefore, it was widely used for dyeing work clothes, uniforms, and also for artistic purposes.

Today, the use of toluidine blue has declined due to its toxicity. If in contact with skin or inhaled, it may cause irritation and allergic reactions. However, this dye is still used in some industries.