PBr 25 – benzimidazolone brown

Manufacturer/ product code:  Kremer / 23495
Chemical Description:  benzimidazolone
Color: brown
Color Index: PBr 25
Date:  from 1960

PBr 25, known as benzimidazolone brown, is a synthetic organic pigment belonging to the benzimidazolone family, which also includes several widely used orange and red pigments. Developed in the mid-20th century, PBr 25 is chemically derived from benzimidazolone intermediates, producing an insoluble pigment with a warm, reddish-brown hue. Its high tinting strength, moderate opacity, and clean, stable color make it suitable for a wide range of artistic and industrial applications.

Benzimidazolone brown is prized for its excellent lightfastness and chemical stability. Unlike many early organic pigments, it resists fading under light exposure and is relatively inert to acids, alkalis, and atmospheric pollutants. This durability makes it a reliable choice for modern painting, printing inks, plastics, and coatings. Its transparency and controlled chroma allow it to be used effectively in glazes, mixtures, and toning applications, providing subtle shading and warm brown tones in both fine art and commercial materials.

In conservation and analytical contexts, PBr 25 is an organic pigment and therefore cannot be detected using elemental methods such as XRF. Identification relies on molecular techniques, including Raman spectroscopy, FTIR, or chromatographic analysis. Its presence in an artwork is a strong indicator of 20th- or 21st-century materials, reflecting the shift toward engineered organic pigments that combine high permanence with vibrant, controllable colors. PBr 25 exemplifies modern synthetic chemistry’s contribution to producing reliable and versatile brown pigments for artistic and industrial use.