PR 12 – permanent bordeaux TRR

Inexpensive, widely used in printing inks but very fugitive

Manufacturer/ product code:  Kremer / 55450
Chemical Description: monoazo, naphthol
Color: red
Color Index: PR 12
Date:  from 1921

PR 12 – Permanent Bordeaux TRR is a synthetic organic pigment belonging to the β-naphthol (BON) azo pigment family, a group widely developed in the early 20th century to supply strong, economical reds for paints, printing inks, and industrial applications. PR 12 is characterized by a deep, dark bluish red with a pronounced wine- or bordeaux-like masstone, from which its common name is derived.

Chemically, PR 12 is a monoazo pigment formed by coupling a diazo component with a β-naphthol derivative. This relatively simple molecular structure gives the pigment very high tinting strength and good opacity for an organic red, allowing small additions to dominate mixtures. In tints, PR 12 can show a cooler, slightly purplish undertone, while in mass tone it appears rich and almost maroon.

In artistic practice, Permanent Bordeaux TRR has been used primarily in student and decorative paints, as well as in inks and coatings where intense color at low cost is important. It mixes readily with yellows to produce muted oranges and with blues to create deep violets and near-blacks, though mixtures can become dull if heavily loaded.

From the standpoint of permanence, PR 12 is not a high-performance pigment. Its lightfastness is generally poor to moderate (often ASTM III–IV), with noticeable fading and loss of chroma under prolonged light exposure, particularly in thin layers and pale tints. It also shows limited resistance to heat and certain solvents compared to more modern reds such as quinacridones or pyrroles.

For conservation and technical analysis, the identification of PR 12 can be useful in dating 20th-century materials, as it is absent from earlier historical palettes and less common in contemporary professional artists’ paints due to its durability limitations.

Overall, PR 12 represents a historically significant but technically limited red pigment: visually powerful and economical, yet unsuitable for works requiring long-term color stability.