Tyrian Treasure: A Surprise from the Archive
In late 2008, I was sorting and listing the contents of a nineteenth and twentieth century industrial archive relating to dye manufacture in Leeds. A small envelope of purple threads fell from the hinges of an upturned rusty trunk: I stared with some incredulity at handwriting in red ink claiming the envelope’s contents to be ‘Tyrian Purple, dyed with the bodies of shellfish found on the African coast'.
It’s well known – in the dye world, at least – that shellfish dyeing largely ceased around the time of the Fall of Constantinople in 1453, after which the last dyers seemed to have disappeared. In the eastern Mediterranean, purple dyeing ceased almost a millennium earlier as a result of the Arab conquest at the beginning of the seventh century. The biochemical method of shellfish dyeing was complex, relying on processes which were not understood chemically, and were probably only passed down within families. When the dyers ‘disappeared’ it is believed the method went with them.
Shellfish dye chemistry
Shellfish pigment must first be made soluble, (as with any dye), and this only occurs in alkaline conditions of around pH 8 and higher. Readers who are indigo dyers will be familiar with its process because an additional requirement for dissolution of the pigment is that it must undergo ‘reduction’. In reduction, the pigment’s molecules are converted to a slightly altered, but more soluble, molecular structure. This reduction process is achieved by removing oxygen from the pigment molecules, or by adding hydrogen to them. The vat turns a yellowy colour and fibre, threads or fabric are introduced. On removal, colour will return to dyed items as they re-oxygenate in the air.
The exact method for creating a true shellfish purple reduction vat was lost to us until the painstaking work in the 1990s of the late John Edmonds. Edmonds knew that shellfish dye was an indigoid, requiring a reduction process. He successfully used shellfish pigment extract for colour, and the rotting flesh of tinned cockles to start the fermentation.
Working with Zvi Koren
Zvi Koren is a respected international authority on shellfish purple whom I have met at several conferences. In 2011, I told him about the envelope of ‘shellfish dyed’ threads I had found. As befits an analytical chemist, Zvi was somewhat sceptical and reminded me that prior to the work of Edmonds and others (including himself) I’d have to go back nearly 600 years to find a true shellfish dyeing supported by modern chemical analysis. Zvi suggested I send him ‘my’ samples for analysis. This would be undertaken, via photomicrographic imagery and instrumental chromatography, at the Edelstein Center for the Analysis of Ancient Artifacts in Israel.
Zvi has described his astonishment when the dyeing turned out to be genuine. He later suggested we co-author a paper to map a possible scenario for how the dyeing came about, why, and at what date. It involved parallel investigations based on Zvi’s analysis; studies of classical and biblical texts; nineteenth century literature; the history of science and scientific connections; and the remarkable Bedford family of Leeds. Our paper was published in 2016. Years
The Bedford Family
The Bedford family first started manufacturing orchil, a purple dye made from varieties of lichen, in around 1820. Three successive and enterprising Bedford generations steered the expanding manufacturing company into the twentieth century, with achievements often based on contemporaneous research. This period saw them incorporate synthetic dyes into manufacturing, but their use of natural products continued far into the twentieth century.
The company changed names several times, but there was never a takeover. As ‘Yorkshire Chemicals’ the business went into receivership in the early 2000s. In 1880-81, Charles Samuel Bedford, grandson of founder James Bedford, attended the Yorkshire College to study chemistry with Arthur George Perkin, the second son of Sir William Henry Perkin.
W.H. Perkin’s 1865 discovery of a synthesised purple dye known as mauveine revolutionised the dye and chemical industry. The meeting of these students developed to a lifelong connection when Arthur married Charles’ Annie. Arthur and Annie spent their lives in Leeds where Arthur worked at what became the University of Leeds. Strong social ties existed between the families.
In our paper, Zvi and I proposed that the family, scientific, and working connections of the Bedfords may explain how samples of genuine Tyrian Purple arrived in the archive. Since there could be no commercial or industrial potential in shellfish dye we must assume there was a purely academic interest in the subject.
The history of chemical discoveries
Zvi’s research confirmed that the purple threads were dyed rather than smeared by direct application.  Therefore, two key things had to be chemically ‘known’ to vat dye the threads. Firstly, the dyer needed to know that shellfish pigment was an indigoid molecule, and secondly that a reduction vat was required. Knowledge of the hydrosulfite reduction vat was first presented in 1873 by Schützenberger and Lalande. Paul Friedländer’s work in 1909 Vienna determined that the main component of purple pigment from shellfish was an indigoid, namely dibromoindigo.
Dyer and date
The Leeds archive was assembled from 1914 onwards by James Bedford, the older brother of Charles. By studying chemical and historical timelines, we arrived at a possible dyeing date of 1910-13. The identity of the dyer remains unknown since no explanatory notes have been found, but the writing on the envelope containing the threads is that of Charles S. Bedford. It’s possible he dyed it himself, had it dyed by an experienced chemical colleague, or it was given to him by someone whose work he trusted.
The demise of Yorkshire Chemicals
The factory on Kirkstall Road, first occupied by the Bedfords in 1850, was abandoned in the early 2000s. I visited the demolition site in 2008 and felt unexpectedly emotional. Rising smoke and heaps of twisted metal seemed a sad legacy for a proud family’s endeavours. But the envelope of purple threads now proves significant to contemporary research and has restored to us genuine samples of Tyrian Purple. They are the first ‘modern’ dyeings currently known since the fifteenth century and embody scientific connections of the time as well as the many achievements of the Bedfords. In Zvi’s words, this century-old Tyrian Purple is ‘the most modern historic dyeing’ yet found. It serves as a lasting tribute to the Bedford family – and is a true historic treasure.
 Two articles on the archive have appeared in the Journal (Whitworth 2008,2010)
 In traditional use (e.g. Oaxaca in Mexico) shellfish have been used to smear fibres or cloth. This produces an uneven colouration that is easily seen under magnification. It is not a reduction process (Mindling, 2009)
By this time there had been no Bedfords working in the company for many years. The archive had passed to the daughter of Charles Samuel Bedford, then to her son Charles Chalcraft who was the owner in 2008.
Doumet, Joseph (1980) Étude sur la couleur pourpre ancienne et tentative de reproduction du procédé de teinture de la ville de Tyr décrit par Pline l'Ancien: A study on ancient purple.
Beirut: Imprimerie catholique. Edmonds, John (2000) Tyrian or Imperial Purple Dye. Historic Dyes Series, No 7, privately published.
Edmonds, John (2005) Trail of the Purple Snail. Journal WSD 214, p.5.
Edmonds, John (2009) Imperial purple. Journal WSD 230, p.14.
Gillespie, Frances (2013) Colour from the Sea. Journal WSD 245, pp.7-9.
Mindling, Eric (2009) Purpura! Shell Dyeing in Oaxaca, Mexico. Journal WSD 230, pp16-18.
Whitworth, Isabella (2008) Archive and Beyond. Journal WSD 227, pp.6-8
Whitworth, Isabella (2010) Beyond the Archive – to Ecuador. Journal WSD 233, pp.22-25.
Whitworth, Isabella and Koren, Zvi (2016) Orchil and Tyrian Purple: Two Centuries of Bedfords from Leeds. Ambix – The Journal of the Society for the History of Alchemy and Chemistry, 63 (3), pp.244-267.
Zvi Koren’s website, from which many papers on shellfish purple are downloadable https://edelsteincenter.wordpress.com/articles/ancient-dyes/
With thanks to Zvi Koren for undertaking this detective story with me, for his great patience giving me scientific explanations, and for lightening things up with his fondness for puns.
About the author
Isabella Whitworth is an artist, dyer, researcher and tutor living and working in Devon. She specialises in resist dyeing.
This article appears in edition #265 of the Journal for Weavers, Spinners and Dyers.
The Journal is published on behalf of the Association of Guilds of Spinners Weavers and Dyers. It covers a wide range of textile subjects, including articles on historic textile techniques and cutting edge modern design.