PB 33 – manganese blue

Artists considered it a perfect blue but it was discontinued in the 90’s

Manufacturer/ product code:  Kremer / 23730
Chemical Description: barium sulfate permanganate
Color: blue
Color Index: PB 33
Date:  from 1935

PB 33, known as manganese blue, is an inorganic synthetic pigment with the chemical composition barium manganate sulfate (BaSO₄·MnO₄). It was introduced in the early 20th century and quickly gained appreciation for its distinctive bright, slightly greenish blue color, reminiscent of turquoise or cerulean tones. Unlike many organic blues of the same period, manganese blue is a true pigment rather than a dye lake, offering good opacity and a clean, luminous hue.

Manganese blue is notable for its excellent lightfastness and chemical stability. It is resistant to acids, alkalis, and atmospheric pollutants, making it a durable choice for artists’ paints and industrial coatings. It performs well in a variety of binding media, including oil, tempera, and acrylics, and shows minimal color change over time. Its relatively low tinting strength compared to phthalocyanine blues allows for controlled mixtures and subtle tonal modulation, which contributed to its popularity in 20th-century painting.

In artistic practice, PB 33 was often used for skies, water, and decorative passages requiring a fresh, cool blue. However, its production involved environmentally problematic manganese compounds, leading to declining manufacture and eventual discontinuation in many countries by the late 20th century. As a result, PB 33 has become less common in contemporary materials. For conservators, the identification of manganese blue is valuable for dating artworks and understanding 20th-century pigment choices, particularly in modernist and postwar painting contexts.