PY 32 – strontium yellow

Used in oil paints in the late 19th and early 20th centuries

Manufacturer/ product code:  chemcraft CAS 7789-06-2
Chemical Description:  strontium chromate
Color: yellow
Color Index: PY 32
Date:  from 1830

PY 32 – Strontium Yellow is an inorganic pigment composed primarily of strontium chromate (SrCrO₄). It is valued for its bright, warm yellow hue with excellent opacity, chemical stability, and lightfastness. Strontium Yellow has historically been used in industrial coatings, plastics, ceramics, and artists’ paints, providing a strong, durable yellow coloration suitable for both decorative and functional applications.

Chemically, PY 32 is a crystalline compound in which the chromate anion (CrO₄²⁻) provides the characteristic yellow color, while the strontium cation stabilizes the crystal lattice. This inorganic structure gives the pigment outstanding resistance to light, heat, and chemical degradation, making it highly durable in demanding applications. However, as a chromate-based pigment, it is toxic and requires careful handling and regulatory compliance.

In practical applications, Strontium Yellow exhibits high opacity and moderate to strong tinting strength. Its bright warm tone blends well with other yellows, oranges, and reds to produce a wide range of warm hues. Its chemical stability ensures color retention in paints and coatings, even under prolonged exposure to sunlight and environmental stress. In artistic applications, it has been used historically as a high-coverage yellow in oil and tempera paints, although its toxicity has limited its use in contemporary artists’ materials.

From a conservation perspective, PY 32 is chemically stable and highly lightfast, maintaining chromatic purity over long periods. Its durability makes it a reliable marker of mid-20th-century industrial pigments.