PR 173 – rhodamine B

PR 173 – Rhodamine B is a synthetic organic pigment derived from the rhodamine family of xanthene colorants, a group best known for producing exceptionally bright and fluorescent reds and pinks. Originally synthesized in the late 19th century as a dye, rhodamine B was later adapted into pigmentary forms for specific applications where extreme chromatic intensity was required.

In terms of color, PR 173 displays a striking bluish-red to fuchsia hue, often perceived as a vivid pink-magenta with an almost luminous quality. It is highly transparent and possesses extremely high tinting strength, meaning even small additions can strongly influence mixtures. Compared to azo or quinacridone reds, rhodamine B appears much cooler and more brilliant, making it particularly effective for eye-catching highlights, optical mixtures, and special visual effects. Its transparency favors use in glazes, inks, and thin films rather than in opaque paint layers.

Technically, PR 173 is limited by poor lightfastness and overall permanence. Exposure to light, heat, and certain chemical environments can lead to rapid fading and color shifts. For this reason, it is generally unsuitable for conservation-grade fine art materials. Instead, it finds use in printing inks, security and signal graphics, fluorescent coatings, and temporary or decorative applications. PR 173 exemplifies the balance between extraordinary visual impact and reduced durability that characterizes many dye-derived pigments.