Orcein
A reddish dye made from lichens, changing colour with acidity
No single value: Orcein is a material, and its colour varies. The background shows its family, purple and violet.
Orcein is a dye obtained from certain lichens, especially Roccella tinctoria, and is known for its reddish-brown to purple hues. Its colour shifts from red in acidic conditions to blue in alkaline ones, and it has been used in textiles and scientific staining, though not as a food dye.
- Orcein is made from lichens like Roccella tinctoria
- Its colour shifts from red to blue depending on acidity
- Cudbear, a form of orcein, was first made in Scotland in 1758
- Cape Verde exported large amounts of orchil in the 1800s
- Orcein is not allowed as a food dye in Europe
What colour is Orcein?
Orcein is a dye that comes from certain lichens, often called orchella weeds. It produces a reddish-brown or purple colour, which can shift depending on how acidic or alkaline the environment is. In powder or paste form, it is used to colour wool, silk, and for scientific staining. Its ability to change colour with pH sets it apart from many other dyes.
Where does Orcein come from?
The name orcein covers dyes made from lichens like Roccella tinctoria. Traditional methods used ammonia from urine to turn lichen extracts into dye. Cudbear, a related dye, was first made in Scotland in 1758 by Dr Cuthbert Gordon, who may have named it after himself or his mother. The dye trade spread to places like Norway, Sweden, France, and Cape Verde, where lichens were gathered and exported.
How is Orcein made?
To make orcein, lichens are first processed to extract orcinol, which is then exposed to ammonia and air. This can be done using traditional materials like urine, or with chemicals such as potassium carbonate, lime, and gypsum. If these extra chemicals are used, the process can yield litmus, a related dye. Commercial orcein is sold as a powder (cudbear) or a paste.
Where Orcein is used
Orcein has been used to dye wool and silk, often without needing extra chemicals to fix the colour. It has also found a place in science, where it helps to stain and reveal structures in cells. In the past, it was a valuable export for places like Cape Verde and was made in guarded factories in Scotland and France.
Purple around the world
What the purple and violet family means from country to country.
In Holy Week, members of religious brotherhoods walk in procession in robes and pointed hoods, many of them purple, the colour of penance. A purple band also marked the flag of the Second Republic.
Sacred and holyPolitics and protestSource: Holy Week in SpainSuffragettes campaigning for women's votes wore purple, white and green: purple for dignity, white for purity and green for hope.
Politics and protestCourageSource: SuffragetteA child born to a reigning Byzantine emperor was called porphyrogennetos, born in the purple. The birth took place in a palace room lined with purple stone.
Royalty and powerAweSource: Born in the purpleIn the elections of 2005, voters dipped a finger in purple ink to prevent double voting. The stained finger, held up for cameras, became a sign of the vote.
Politics and protestPrideSource: Election inkPurple dye from the murasaki plant was costly and hard to make. In the court rank system set up under Prince Shotoku, the highest officials wore purple caps.
Royalty and powerAweSource: Twelve Level Cap and Rank SystemThe Phoenician cities of Tyre and Sidon made Tyrian purple from sea snails. The dye was so costly that it became the colour of kings and Roman emperors.
Royalty and powerAweSource: Tyrian purpleShades and relatives of Orcein
Cudbear is a form of orcein that gives purple shades and was one of the first modern dyes. French purple is another related dye, made by a similar process but with extra steps to improve its stability. Orcein is sometimes confused with orchil, which is more purple-blue, and with litmus, which is made by a related process.
Questions people ask about Orcein
What colour is orcein?
Orcein appears reddish-brown to purple, and its exact shade depends on how acidic or alkaline the environment is.
Where does the name orcein come from?
The name orcein refers to dyes made from lichens, especially those called orchella weeds; cudbear, a related dye, was named by Dr Cuthbert Gordon in Scotland.
How is orcein made?
Orcein is produced by extracting orcinol from lichens and treating it with ammonia and air. Traditional methods used urine as the ammonia source.
What is cudbear?
Cudbear is a purple dye made from lichens by a process similar to orcein. It was first produced in Scotland and used to dye wool and silk.
Is orcein safe to use in food?
Orcein is not approved for use as a food dye and has been banned in Europe since 1977.
Good reading and sources
The facts on this page come from the Wikipedia article "Orcein", 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.
More of the purple and violet family
All of purple and violet
Purple and violet
Tyrian purple
A reddish-purple dye once worth its weight in silver, made from sea snailsDye 路 馃嚤馃嚙 Lebanon +4
Purple and violet
Crystal violet
A synthetic purple dye used in science, medicine, and industryDye
Purple and violet
Logwood
A tree whose wood yields a dye once vital for textiles and scienceColour named from nature 路 馃嚥馃嚱 Mexico +3
#E0B0FF
Mauve
A pale purple named after the mallow flower and once a fashion sensationNamed shade 路 馃嚝馃嚪 France
Purple and violet
Mauveine
A purple dye first made by accident in 1856, launching the synthetic dye industryDye
#9966CC
Lavender
A pale purple named for the lavender flower, with many subtle variationsNamed shade
#CC8899
Puce
A brownish-purple shade named after the flea and once favoured in French fashionNamed shade 路 馃嚝馃嚪 France +1
#8E4585
Plum
A purple shade named for the colour of plum fruitNamed shade
More colours tied to Norway
The colours of Norway
#801818
Falu redfalu r枚df盲rg
A deep red paint pigment from the Falun copper mine, used on wooden houses in SwedenPigment 路 馃嚫馃嚜 Sweden +2
#FFFEEF
Titanium white
A bright white pigment made from titanium dioxide, valued for its strong coveragePigment 路 馃嚭馃嚫 United States +1
White
Titanium dioxide
A brilliant white pigment made from titanium, used in paints, food and sunscreenPigment 路 馃嚚馃嚦 China +5
Yellow
Chrysothrix chlorina
A yellow to yellow-green powdery lichen used as a dye in India and SwedenColour named from nature 路 馃嚫馃嚜 Sweden +5