Pigment Red 3
A dark red azo pigment once common in oil paints
No single value: Pigment Red 3 is a material, and its colour varies. The background shows its family, red.
Pigment Red 3, also called Toluidine red, is a dark red organic compound used as a pigment. It is an azo dye based on a 2-naphthol group joined to a 2-nitro-4-methylphenyl group. Once popular in oil painting, it is now less used because it fades in light and can bleed in paint. It is classified as carcinogenic.
- A synthetic dark red pigment used in oil paints
- Classified as an azo dye with a 2-naphthol base
- Known for fading and bleeding in paint
- Considered carcinogenic like many azo dyes
What colour is Pigment Red 3?
Pigment Red 3, or Toluidine red, is a synthetic dark red pigment. It is an organic compound, meaning it is made from carbon-based chemicals rather than minerals or metals. The colour is deep red and solid, falling into the group of azo dyes, which are known for their strong colours. This pigment stands out from other reds for its chemical structure and its use in oil paints.
Where does Pigment Red 3 come from?
The name Toluidine red comes from its chemical makeup, which includes a toluidine (methylphenyl) group. It is also called Pigment Red 3 in pigment classification. The pigment became widely used in art after synthetic dyes were developed, but its popularity has faded due to technical drawbacks.
How is Pigment Red 3 made?
Pigment Red 3 is made by linking a 2-naphthol group to a 2-nitro-4-methylphenyl group, creating an azo compound. Azo dyes are made through a chemical reaction called diazotisation, which joins two parts together to form a strong colour. The result is a dark red powder used in paints.
Where Pigment Red 3 is used
Toluidine red was once a common pigment in oil paints. Artists valued its strong red colour, but it is now less used because it fades when exposed to light and can bleed, or spread, in paint mixtures. These problems make it less reliable for lasting artworks.
What Pigment Red 3 means
There are no specific cultural or emotional meanings tied to Pigment Red 3 in the sources. Its main importance is as a pigment for artists, not as a symbol.
Red around the world
What the red family means from country to country.
The flag uses the four Pan-Arab colours: a red bar at the hoist with green, white and black bands. It was designed by a young Emirati, Abdullah Al Maainah, in 1971.
Politics and protestPrideSource: Flag of the United Arab EmiratesThe flag is a black double-headed eagle on red, the banner of the fifteenth-century hero Skanderbeg. Fans chant Kuq e Zi, red and black.
Politics and protestPrideSource: Flag of AlbaniaArmenian scribes painted manuscripts with vordan karmir, a crimson dye made from an insect that lives on the roots of grasses in the Ararat plain.
Sacred and holySource: Armenian cochinealUnder Juan Manuel de Rosas in the 1830s and 1840s, everyone had to wear a scarlet ribbon to show loyalty to his Federalist party. His enemies, the Unitarians, were tied to sky blue.
Politics and protestFearSource: Juan Manuel de RosasThe flag is red, white and red. Legend says Duke Leopold V's white tunic was soaked in blood at the siege of Acre, all but the band under his belt.
Politics and protestCourageSource: Flag of AustriaRed ochre is used in Aboriginal rock art and ceremony, and is traded over long distances. In the Aboriginal flag the red half stands for the earth and for that ochre.
Sacred and holyNature and renewalAweSource: Australian Aboriginal flagShades and relatives of Pigment Red 3
Pigment Red 3 belongs to the larger group of azo red pigments. It may be confused with other azo reds, but its chemical structure and problems with lightfastness set it apart. Other red pigments may be more stable or have different shades.
Questions people ask about Pigment Red 3
What colour is Pigment Red 3?
Pigment Red 3 is a dark red colour. It is a strong, deep red used in oil paints and is also called Toluidine red.
Where does the name Toluidine red come from?
The name comes from its chemical structure, which includes a toluidine (methylphenyl) group. It is also known as Pigment Red 3 in pigment classification.
What is Pigment Red 3 made from?
It is made by chemically joining a 2-naphthol group to a 2-nitro-4-methylphenyl group, forming an azo dye.
Why is Pigment Red 3 less used today?
It is less used because it lacks lightfastness, meaning it fades in sunlight, and it can bleed in paint, making it unreliable for lasting artworks.
Is Pigment Red 3 safe?
Pigment Red 3 is classified as carcinogenic, a property it shares with many other azo dyes. Care is needed when handling it.
Good reading and sources
The facts on this page come from the Wikipedia article "Toluidine red", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Rang rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. The swatch is an approximation: named colours are not fixed standards, and every screen shows them a little differently. If something is wrong, tell us. Last refreshed 2026-10-03.
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