Ponder the Putrid History of Purple Dye

The stinky process of making the royally sought-after purple dye involved mollusks subjected to biochemical, enzymatic and photochemical reactions — and possible sacrificial rituals.
Aug. 5, 2024
4 min read
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Hexaplex trunculus snail

Tinctis murice vestibus quod omni et nocte utitur et die Philaenis non est ambitiosa nec superba: delectatur odore, non colore.

- Martial (c.80 AD)
Written almost 2,000 years ago, Roman satirist Martial’s epigram translates as: “Philaenis wears purple-dyed garments every night and day, but she is not ostentatious or haughty; she likes the odor, not the color.” 
 
Philaenis, reputedly the author of an ancient sex manual, is another day’s work. Here Martial is poking fun at efforts to mask her body odor. 
 
There’s a very good chance the strategy worked, too, given that the process involved in making the much sought-after purple dye was legendarily smelly. 
 
The process, thought to date as far back as 3,000 BC, was developed by Phoenicians from Tyre in modern-day Lebanon, hence the name Tyrian purple. 

Processing centers were located downwind of nearby populations.

Elsewhere, Martial alludes to the city of Tyre retaining a permanent fishy smell because of its dye manufacturing activities. Indeed, he composed a list of bad-smelling things that couldn’t equal it, including sulfurous waters, an amorous goat and the old shoes of a veteran soldier. Hence why centers of processing were located downwind of nearby populations.
 
Worth more than its weight in gold, in Martial’s time, two pounds of Tyrian dye retailed for about $60,000 at today’s prices. Julius Caesar and Caesar Augustus made laws that only the Roman Emperor could wear purple and Martial’s contemporary Nero made it a capital offence to wear or even be involved in its sale.
 
The manufacturing process started by harvesting sea snails from the Muricidae family of predatory marine mollusks. To manufacture about one gram of Tyrian purple required 10,000 snails, weighing in at about 50 kg.
 
Archaeological evidence from around the region suggests the next step involved either hand harvesting the mollusks’ dye-containing mucus glands or crushing the creatures wholesale.
 
Either way, the raw materials were mixed with salt water and left steeping in vessels or vats, sometimes with gentle heating, for up to three weeks. The choice of container is thought to have been important because it allowed some control over the oxygen and light supply that drove the biochemical, enzymatic and photochemical reactions occurring in the brine, hence the shade of purple obtained.  
 
Fabrics were then soaked in the dye solution until they achieved the appropriate shade of purple. 
L.Berger
Figure 1. A purple snail pit in Kolonna. Left before excavation and right during excavation.
Figure 1. A purple snail pit in Kolonna. Left before excavation and right during excavation.
A new study carried out by researchers from the University of Vienna, Austria, and published in a recent issue of PLOS ONE, sheds further light on the process and hints at associated spiritual practices.
 
The researchers — specialists in classical archaeology, veterinary science, forensic medicine and analytical chemistry — have been investigating a largely undisturbed purple dye workshop at Kolonna on the Greek island of Aegina.
 
In its cultural heyday, about 2,000 BC, Kolonna was a densely built and strongly fortified settlement that experienced a period of economic prosperity. At some point between 1,900 and 1,700 BC, purple dye production began. 
 
The Austrian team has unearthed raw material and debris in the form of crushed murex shells, tools and facilities, including pounders, a grinding stone and a waste pit, plus the finished product — dye pigment. 
 
Enough of the pigment remained on pottery fragments from different vessels to be analyzed by high-pressure liquid chromatography.  
 
This revealed the banded dye-murex Hexaplex trunculus was used almost exclusively at Kolonna. It’s an unusual finding for the region, suggesting this mollusk had an overwhelming dominance in that area or that the manufacturers hadn’t heard of the evolving “double dyeing” process, which used pigments from both Hexaplex trunculus as well as Bolinus brandaris.
 
Note to Philaenis: Kolonna dye even now emits a slightly fishy odor when mixed with water.
The “remarkable homogeneity” of the pit sample suggests that the mollusks were hand-collected, possibly by divers. 
 
No reliable estimate of the scale of purple dye production is possible, as there is no evidence of the frequency of emptying and refilling the waste pit. However, the ubiquitous admixture of partly trampled purple shell fragments suggests at least continuous, perhaps professional activities. A network of nearby ditches and basins, yet to be excavated, could also play a part in the process.
 
However, within the excavated area of the purple workshop, the team did find skeletal remains of heavily burnt infantile and juvenile piglets, kids and lambs.
 
Noting the complete destruction of the burnt remains of restricted age, sex, species, body part, and treatment, the team suggests the animals were used in ritual activities aimed at promoting the highly meaningful event of purple production rather than normal food consumption practices. 
 

About the Author

Seán Ottewell
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Seán Ottewell

Editor-at-Large

Seán Ottewell is a freelance editor based in Ireland. He has an impressive background in the chemical industry. After earning his degree in biochemistry at Warwick University, UK, he earned his master's in radiation biochemistry from the University of London. His first job out of school was with the UK Ministry of Agriculture, Fisheries and Food, London, where he served as scientific officer with the food science radiation unit.

From there he entered the world of publishing. In 1990, he was the assistant editor of The Chemical Engineer, later moving on to the chief editor's position. Since 1998, he has been a regular contributor to European Process Engineer, European Chemical Engineer, International Oil & Gas Engineer, European Food Scientist, EuroLAB, International Power Engineer, published by Setform Limited, London, UK.

Chemical Processing has been proud to call Ottewell Editor at Large since 2007.

He and his family run a holiday cottage in the small village of Bracklagh in East Mayo. He also fancies himself an alpaca farmer.

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