Collection Care blog

As part of the Hebraic Manuscript Digitisation Project (HMDP), we are currently imaging 74 scrolls. These range in size from one smaller than a little finger to another a whopping 52.41m long – three times the length of the conservation studio. The tallest is nearly a metre with its rollers.

Esther scroll in decorative case (Add 11831)

We did a brief survey last year and realised some of the scrolls were very damaged, so we have spent another two months assessing each one individually. Even this was not a simple task. Many of the larger scrolls are also very heavy, so two conservators have worked together to make sure they were handled safely, using lots of weights as stops to prevent them rolling off work-surfaces. The parchment scrolls have been tightly rolled for a very long time and even looking at them has been a challenge, as they try hard to re-roll themselves unless held down securely.

Text was rewritten after surface delamination; plus insect damage and excreta (Or 4224)

What are they? As well as some fine large Torah scrolls on parchment, made for synagogue use, we also have a number written on leather. The most important of this group is the Kaifeng Torah, made in central China in the 17th century. Read more about it here. 

There are also much smaller scrolls made for personal or family use. In particular, we have quite a few Esther scrolls, and some with the ritual texts for the Passover meal. Most copies of Hebraic scriptures are unadorned, to focus attention on the religious texts, but scrolls for family celebrations may have decorative margins or full coloured miniatures. The smallest scroll, adorned with silver, was almost certainly an amulet as the script is too tiny to be easily read.

 The smallest scroll. The finger appears huge in comparison to the tiny script. (Or 4670)

The survey showed that up to half of the scrolls needed some kind of conservation treatment. Many were quick tasks done during assessment (edge tears or broken sewing joining panels) to avoid having later to roll and re-roll the scroll yet again. However, a dozen of the scrolls needed a good deal of repair simply to get them through the digitisation processes safely, and were sent to the main conservation studio.

Sewing is too tight and the holes too close together. The leather surface is also crazed and inflexible in part. (Or 1462)

Many of the scrolls have integral rollers. We thought it safer not to repair these if broken, lest it give a false sense of security, though we never lift scrolls by the roller handles anyway, since so many are now frail. Even more fragile are the few scrolls that roll back into cases as the mechanisms now tend to stick. Thankfully, once digitised, these will be handled rarely.

Common damage: the sewing has broken and a tear has developed across the text. This must be repaired before imaging as handling will make it worse. (Or 4224)

The scrolls are made of rectangular panels of parchment or leather (often called membranes) joined end to end. We were surprised to find that the majority were linked only by long, crude running stitches of linen thread, but these joins had mostly remained intact. We understood this better when we found a pair of scrolls with joins of fine oversewing (possibly done by a seamstress, not a leather worker), where the thread had torn through the leather; the frequent holes essentially acting as a perforation strip.

Evidence of use is carefully preserved; here molten wax has dripped onto the scroll. (Or 1463)

A few of the scrolls have protective silk panels stitched to the verso at the outer end and we also found four mantles. Our textile conservator, Liz Rose, is cleaning and repairing these to make them safe to handle and image. They will be boxed separately and available for display in the future. As part of the project, many of the scrolls will also be rehoused in custom-made boxes.

An extremely damaged mantle; the silk lining is also split in many places (Or 13027)

Although our imaging technicians are well used to digitising oriental scrolls, as well as other rolled materials such as maps, we think this is the first time anyone has digitised such a large group of Hebraic scrolls. Conservators were involved early in the process of selecting suitable equipment. Although no Hebraic manuscript books have been scanned, we concluded that it would be safer and more efficient to scan some of the scrolls – though using the equipment unconventionally, without the glass sheet to flatten them. There was a full risk assessment before imaging began, and the imaging technicians received specialist handling training, including a requirement to work in pairs.

Marginal decoration of an Esther scroll (Or 1047)

Image printed on parchment and hand coloured. The printing block was probably generic, used to decorate many different texts, but is unusual for a Hebraic manuscript. (Or 13028)

Conservation’s role in the digitisation of the scrolls is now finished, but there is still several months’ work to be done on processing and stitching the images before everything is uploaded to our website. Meanwhile, you can view many of the books digitised during the project here: using “Hebrew” as the keyword.

Ann Tomalak, HMDP Phase 1 Project Conservator

We recently held a very successful public event sharing our conservation work in preparation for the British Library Magna Carta: Law, Liberty, Legacy exhibition. The exhibition marks 800 glorious years of Magna Carta since it was granted by King John of England in 1215. The conservation project involved removing six manuscripts from their frames and rehousing them for display. While they were out of their frames, the manuscripts were examined using various scientific techniques. High-resolution digital microscopy enabled incredible magnification of the iron gall ink and parchment which make up the charters. Here is a selection of the images captured of Cotton MS Augustus ii.106, one of the British Library’s two original Magna Carta manuscripts dating to 15 June 1215. Enjoy!

Imaging Scientist Dr Christina Duffy operating a digital microscope at the British Library.

Magna Carta 1215 (Cotton MS Augustus ii.106) – one of four surviving original 1215 copies.

Iron gall ink

Iron gall ink has been used since the middle-ages and is found on many of our most treasured collections including the Lindisfarne Gospels, Beowulf and Magna Carta. The main ingredients of iron gall ink include iron sulphate, tannins from oak galls and water. Overall the ink is in very good condition on this charter allowing us to appreciate the beauty in the detail of some of the initials.

Magna Carta 1215 detail.

Iron gall ink at 20 times magnification.

Iron gall ink at 30 times magnification.

Iron gall ink at 150 times magnification.

At high magnification we can see that some areas have experienced ink loss, but the Great Charter is still legible due to the remaining ink shadow left behind. Find out more about iron gall ink in a previous post here.

Magna Carta 1215 detail right side.

Ink loss at 30 times magnification.

Ink loss at 100 times magnification.

Ink loss at 200 times magnification.

Parchment

The parchment on which Magna Carta has been written is thought to be sheepskin. Parchment is an animal pelt which has had the hairs removed by liming or enzymatic action. It is then stretched and dried under tension creating a perfect writing surface with a thin opaque membrane. Below are some images showing damage to the  upper dermal layers of the parchment. Find out more about parchment here.

Magna Carta detail at the centre of the manuscript.

Damage at 30 times magnification.

Damage at 50 times magnification.

Damage at 150 times magnification.

You can find out more about this charter on the British Library Magna Carta resource page.

Christina Duffy (@DuffyChristina)

We’re delighted to announce that the conservation team behind the work done on the British Library collections in our latest exhibition Magna Carta: Law, Liberty, Legacy will be speaking at a public event on Friday 26 June 2015 18:30 - 20:30 to share their findings. Speaking on the night in the British Library Centre for Conservation will be Head of Conservation Cordelia Rogerson, conservator Gavin Moorhead, conservation scientist Paul Garside and imaging scientist Christina Duffy. Book your place here.

Join our project team of conservators and scientists on 26 June 2015.

The project spanned over three years in preparation for this year’s 800th anniversary of the 1215 Magna Carta and involved the reframing and scientific analysis of all of the Magna Carta charters held in our collections, including the two 1215 original versions.

Conservator Gavin Moorhead works on the 1215 Articles of the Barons (Additional MS 4838).

The team undertook an initial examination of the original frames to determine their structure and composition. At the event you’ll hear how probes were manually inserted into the frames to take samples of the air inside in order to determine what kind of micro-environment the charters were living in! The stability and compatibility of new materials, which would be used for mounting in the new frames, was ensured using infrared spectroscopy, pH tests, and lignin tests.

Mounting materials were tested before incorporation into the new frames. Join us to find out what the blue and red colours indicate.

With the frames removed the team had a rare opportunity to investigate the condition of the manuscripts using near-infrared spectroscopy and high resolution digital microscopy. Unpublished images of the ink and parchment at up to 200 times magnification will be shared with the audience.

What does 800-year-old ink look like at 200 times magnification? 

You will also delve deep into the exciting world of multispectral imaging and see versions of the charters and their seals under ultraviolet and infrared light. The incredible results of the text recovery project on the damaged 1215 Canterbury Magna Carta, from which much of the ink was lost, will be shared.

Once our tests were complete it was time to rehouse the charters – you’ll hear from our conservator Gavin Moorhead about the challenges and decisions required to mount for display one of the most recognised manuscripts in the world which would feature as the dramatic finale to the exhibition.

The British Library's London Magna Carta at our exhibition, Magna Carta: Law, Liberty, Legacy.

Don’t miss out on this great event and book your place now! We look forward to meeting you!

Christina Duffy

With the recent multispectral imaging of the burnt Magna Carta hitting the headlines following our blog post on the 800 year old Magna Carta revealing its secrets, there has been a lot of interest in the conservation work required to protect such items. The so-called “burnt” Magna Carta (Cotton charter xiii 31a) suffered fire damage in Ashburnham House in Westminster on 23 October 1731. This 1215 exemplification formed part of an exquisite library assembled by English antiquarian Sir Robert Cotton during his lifetime (1571-1631). Cotton’s library forms the basis of our collections at the British Library today, and a recent conservation survey of the burnt material has allowed us to categorise items based on their relative condition, enabling us to immediately identify items suitable for digitisation. This has vastly improved our workflow allowing digital access to a wider audience in a shorter time. 

This piece includes material from an article published by Taylor & Francis Group in Journal of the Institute of Conservation on 29 November 2013, available online at: http://www.tandfonline.com/doi/abs/10.1080/19455224.2013.815122#.VFDzZvmsWtB.

The burnt 1215 Magna Carta suffered fire damage and subsequent interventive treatment. The vulnerable wax seal of the charter melted and distorted in the intense heat. 

 

In the Ashburnham House fire a quarter of the manuscripts were either damaged or destroyed in the blaze, and attempts to extinguish it exacerbated that damage. The documents suffered shrinkage and distortion, bindings were carbonised, ink was lost, soot and dirt was ingrained, tide marks formed on the leaves, and parchment (animal skin) gelatinised. Gelatine is the brownish end-product of a rapid degradation of parchment collagen. Remedial work caused further damage with many of the manuscripts broken up and rebound during salvage. Incorrect reassembly impacted on the codicological history of many of the manuscripts. The darkened gelatinous material which formed along the edge of the parchment was trimmed away from some manuscripts. Unidentified fragments were gathered and put into drawers.

The collection was untouched until the establishment of the British Museum in 1753, where over the coming years invasive treatments were recorded. To separate the leaves which had glued together by gelatinisation, about 40 manuscripts were immersed in a hot aqueous solution (likely to be ethanol in water). Incisions along the parchment edges were made to allow the leaves to dry flat under pressure. Despite the efforts, leaves remained brittle and fragile. Inlaying of parchment fragments into paper was completed in 1856, but a huge number of fragments remained loose and unidentified. While the edges of loose fragments were protected by this inlaying method, over time the degradation of materials caused further concern. The brittle fragments were susceptible to break with every page turn, and acidic paper in heavy volumes tended to cockle preventing the volumes from closing.

Cotton Tiberius A. XII. Parchment fragments were attached to paper in the nineteenth century and incisions were cut along the sides to allow the leaves to lay flat.

 

Our conservators surveyed 243 items from the Cotton Collection, including 21 paper manuscripts. Items were graded on their physical, chemical and overall conditions based on an assessment of the state of the binding and parchment substrate, and thus rated for treatment priority.

Results of the survey of 243 Cotton Collection volumes. From Figure 2 and 5 in The conservation of the burnt Cotton Collection in the Journal of the Institute of Conservation, 2013

Pattern of damage where D (High degree of damage) accounts for 61% of the total items examined. From Figure 2 and 5 in The conservation of the burnt Cotton Collection in the Journal of the Institute of Conservation, 2013.

The nineteenth century treatments have been fundamental to the preservation of the Cotton Collection, and many items thought to be lost have since been rediscovered. The condition survey enabled us to quantify the damage and develop a strategy for the long-term preservation of the burnt Cotton Collection. Items identified as being fragile were immediately withdrawn from library use, while research to determine the best methods of stabilising and housing the items was undertaken. The use of analytical techniques such as near-infrared (NIR) spectroscopy for assessing the deterioration or parchment has enabled a better awareness of the nature and condition of these manuscripts. This information has helped to support the choice and realistic scope of conservation methods. In the case of the burnt Cotton Collection, the future project is now directed towards a preservation approach, including digitisiation and multispectral imaging, rather than an interventive conservation one.

Christina Duffy (@DuffyChristina), Imaging Scientist

Further reading

The conservation of the burnt Cotton Collection, Mariluz Beltran de Guevara and Paul Garside, Journal of the Institute of Conservation, 2013. Vol. 36, No. 2, 145 –161, http://dx.doi.org/10.1080/19455224.2013.815122

Collection Care fired up for BBC Four appearance, Christina Duffy: http://britishlibrary.typepad.co.uk/collectioncare/2013/08/collection-care-fired-up-for-bbc-four-appearance.html

Crisp as a Poppadom, Ann Tomalak: http://britishlibrary.typepad.co.uk/digitisedmanuscripts/2013/02/crisp-as-a-poppadom.html

‘Their Present Miserable State of Cremation' the Restoration of the Cotton Library, Andrew Prescott: http://www.uky.edu/~kiernan/eBeo_archives/articles90s/ajp-pms.htm

After a glorious week of studying European Bookbinding (1450-1820) at the London Rare Books School with Director of the Ligatus Research Centre, Professor Nicholas Pickwoad,  it quickly became apparent that works of art have been one of the best methods of recording details of techniques used in bookbinding.

The majority of books throughout history are not the heavily decorated and spectacular versions we tend to hear most about, but instead are plain, and fairly ordinary book blocks (which some people still find quite exciting - author included!). For this reason, the techniques are perhaps not as well understood or documented. Luckily the keen eye of the artist has captured precise details when depicting books throughout history, showing sewing structures, stitch types, supports, covers and even how they were stored. In this post we will look at some examples of books depicted in art.

Storage

While we now consider spine outwards as ‘the right way around’ to display books, this was not always the case. In the oil on canvas painting ‘Portrait of Lawyer Francesco Righetti’ by Guercino (1626- 28) we see doctor of laws Fracesco Righetti depicted in his library. His law books are tail-edge outwards showing endband detail with titles written on the volume.

Figure 1:  Guercino’s ‘Portrait of Lawyer Francesco Righetti’.

The engraved ‘Portrait of William Cartwright’ (from ‘Comedies, tragi-comedies, with other poems’) was printed in London for Humphrey Moseley in 1651. Cartwright is shown wearing a collar and gown leaning on an open book. The books on the wall behind him are shelved fore-edge out; a common practice in the 16th and early 17th century. Gilded-edge books stored spine away would gleam off the shelves quite spectacularly. Many medieval books have their title written in several places such as the spine, tail-edge or fore-edge as storage locations changed over time.

Figure 2:  ‘Portrait of William Cartwright’. See the full engraving digitised on the British Museum's Image Gallery.

How binderies operated

Hendrik de Haas’s print ‘De Boekbinder’ (1806) shows a bookbinder's workshop. On the left is the beating stone where gatherings were pounded with a mallet for compaction. Second from the left a man is shown bent over a special shaving knife which is drawn along the text block to trim the pages. The shavings are shown on the floor. In the centre on a stool a binder is sewing the gatherings next to a young boy taking a book to a client. The master of the workshop (as determined by his smart attire and rather dashing wig) burnishes the leather by working and smoothing it. The finisher, working for the aristocracy, made more money than the binder – it is unusual to see him wearing Hessian boots. (With tassels? On a binder? The outrage!)

Figure 3: Bookbinder’s workshop in print by Hendrik de Haas, ‘De Boekbinder’, Dordrect, 1806.

Figure 4: Left: Beating the gatherings. Right: Shaving the book block.

Figure 5: Pressing the books in Bookbinder’s workshop in print by Hendrik de Haas, ‘De Boekbinder’, Dordrect, 1806. 

Leaning against the shelving unit in the far right is a wooden book press where several books are packed tightly. It was possible to apply guilt edges to several books at a time when stored in this way.

Life and social status

Dutch painter Marinus van Reymerswale’s early 16th century oil on canvas painting ‘St Jerome in his Study’ shows St Jerome surrounded by curious objects which represent attributes referring to his life and status. St Jerome was famed for translating the Bible into Latin from Greek and Hebrew. The Vulgate, as his translation was known, became the official Latin version of the Holy Script in the Roman Catholic Church. For this reason he is nearly always depicted around books and in his study.

An expensively bound volume with clasps is shelved behind St Jerome, while on his table are several working copies with various sewing structures and tacketed bindings. A sewn book block is apparent which never had covers, adhesive, or a spine lining. The gatherings are visible with long stitch through separate supports rather than covering the whole spine. There is no adhesive used in long stitch bindings, making them very useful for music manuscripts as the book stays open easily and is very flexible. Long stitch was rare in England but common in the Low Countries as a cheap and quick way to produce almanacs. The variety of books in his study suggest St Jerome was highly-literate with a great depth of knowledge.

Figure 6: Marinus van Reymerswale’s ‘St Jerome in his Study’, 16th century.

Figure 7: Left: Leather bound volume with metal clasps. Right: Visible sewing structures, long stitch and tacketed binding. 

Textblocks could be sold without significant covers, just held together with an "endless cover". Jean Antoinette Poisson (Madame de Pompadour) was the mistress of King Louis XV, as well as a prominent patron of Francois Boucher. In Francois Boucher’s 1756 oil on canvas portrait ‘Madame de Pompadour’ the lady is sumptuously dressed and surrounded by opulent things - apart from the book she holds in her hand. The book has a drawn-on cover – a piece of paper or parchment put around the book-block. It was a cheap and quick way to bind books and there are a lot of French books bound in this way. Madame de Pompadour is displaying a casual relationship with literature, in a sense saying to the viewer ‘Look at me, I read books because they are interesting. If I like it, I will keep it” (and pay more money for the binding!).

Figure 8: Francois Boucher’s ‘Madame de Pompadour’, 1756, oil on canvas portrait.

Figure 9: Francois Boucher’s ‘Madame de Pompadour’, 1756, oil on canvas portrait. The book has a drawn-on cover – a piece of paper or parchment put around the book-block.

Street vendors/book peddlers

'Bealux abc belles heures’ is part of the ‘le Cris de Paris’ genre illustrating Parisian street vendors. It is a woodcut engraving ca 1500 showing a moment in time when prayer books, once restricted to the wealthy aristocracy, became affordable to the bourgeois with the advent of the printing press. Thin, printed copies were sold on the streets. In the vendor’s right hand is a Book of Hours showing a limp cover. Underneath his left hand we can see detail of a leather binding.

Figure 6: Street vendors and book peddlers were often depicted in artworks. Left: Beaulx abc belles heures. Right: Tavolette, e Libri per li putti.
 

Similarly in Annibale Carracci’s 1646 print ‘Tavolette, e Libri per li putti’ a man is depicted selling books from a basket that he carries over his shoulder. The book in his right hand has a cover which follows the spine when open and is bound using long-stitch.

Evidence-based research

While written documentation of binding styles and techniques is not always available, we can gather a lot of information from paintings, prints, engravings and illuminations. Sometimes they can tell us more than current literature on a subject – for example in Lorenzo Lotto’s oil on canvas ‘Portrait of a Young Man in his Study’ (c. 1530), the sitter is more likely to be a merchant than a student as the volume he is perusing is bound with a fore-edge flap – this style was used for account books and book-keeping, not for great works of literature.

Figure 7:  Lorenzo Lotto, ‘Portrait of a Young Man in his Study’ (c. 1530), oil on canvas.

Visual depictions can also be useful in filling in missing parts of our understanding. Folio 291v of the great 9th century illuminated gospel manuscript, the Book of Kells, shows Christ holding a red binding decorated with blind twilling. With the original binding of the manuscript now lost, it is possible that this is what it may have originally looked like.

Figure 8: The Book of Kells, f. 291v; a 9th century gospel manuscript containing the four Gospels in Latin based on the Vulgate text which St Jerome completed in 384AD. It has been fully digitised by Trinity College Dublin.

While bookbinding may be considered the Cinderella of the bibliographical trade (i.e. given little care or attention) it is a fascinating area of research, based on the logic of commerce – techniques and styles were not varied unless they needed to be. For more information on bookbindings see the British Library Database of Bookbindings or the Ligatus website.

Christina Duffy (@DuffyChristina)

The Lindisfarne Gospels is one of the most magnificent manuscripts of the early Middle Ages. It was written and decorated at the end of the 7th century by a monk named Eadfrith who would go on to become Bishop of Lindisfarne and serve from 698 until his death in 721. An Old English gloss between the lines translates the Latin text of the Gospel and is the earliest surviving example of the Gospel text in any form of the English language. This translation was a late (mid-10th century) addition by Aldred, Provost of Chester-le-Street.

As one of the Treasures of the British Library the Lindisfarne Gospels undergoes strict condition assessments to ensure it is kept at ideal environmental conditions. Part of this assessment involves using microscopy to take a detailed look at the pigment behaviour. We posted some images in a previous post: Under the microscope with the Lindisfarne Gospels, and here we share some of the exceptional exuberance found on folio 3r.

Folio 3r

 Folio 3r of the Lindisfarne Gospels, Cotton MS Nero D IV. Examine in full detail here

The abstracted decoration found throughout the Lindisfarne Gospels is a spectacular example of Anglo-Saxon art. There are five major decorated openings in the manuscript, the first of which is found on ff. 2v – 3 and introduces the letter which St Jerome addressed to Pope Damasus. It was Pope Damasus who requested a revision of the Latin Bible text during the late 4th century. Folio 2v consists of an elaborate cross-carpet page and faces Jerome’s letter to Damasus in Latin with the opening Novum opus (New work). The intricate detail on this page has been interpreted as an act of personal spirituality and devotion. A few examples are shown below. Enjoy!

Top of folio 3r

Top of folio 3r

Folio 3r letter 50x

Folio 3r 150x

Folio 3r detail 50x

 Top: Upper section of folio 3r. Centre: Crackled pigment of lettering reading incipit prologus at 50x and 150x magnification. Bottom: Celtic-influenced spiral motif at 50x magnification

Centre of folio 3r

Tiny drops of red lead are also observed in early Irish manuscripts which heavily influenced the Lindisfarne Gospels. The Germanic zoomorphic style is evident with interlacing animal and bird patterns.

Centre of folio 3r

Folio 3r 20x

Folio 3r pigment 50x

Folio 3r red lead 20x

  Top: Central section of folio 3r from the British Library Catalogue of Illuminated Manuscripts with creature detail at 20x and 50x magnification. Bottom: Drops of red lead in a geometric pattern at 20x magnification

Bottom of folio 3r

Decorated initials exhibit yellow pigment (orpiment) bordered with drops of red lead. Craquelure is a network of tiny cracks caused by pigment shrinking due to age. When the disruption consists of perpendicular lines it is referred to as crackling.

Bottom of folio 3r

Folio 3r 30x

Folio 3r 100x

Folio 3r pigment loss 20x

Folio 3r 50x

 Top: Lower section of folio 3r. Detail of decorated initals at 30x and 100x magnification. Bottom: evidence of loss of green pigment (verdigris or vergaut) from a decorated initial at 20x and 50x magnification. Text from the reverse (f. 3v) is shown through the parchment

For more details on the pigments used in the Lindisfarne Gospels see our previous post. The entire manuscript is digitised and available online here.

Christina Duffy (Twitter: @DuffyChristina)

Purple coloured pages of vellum are sometimes found in sacred texts adorned in gold or silver lettering. They can be seen in folios 2-5 of the recently digitised Cotton Titus C XV on the British Library's Digitised Manuscripts website. Fragments of the Codex Purpureus Petrolpolitanus (a 6th century copy of the Four Gospels in Greek) demonstrate the use of purple as an indicator of wealth, power and kingship. Purple parchment was once only used for Roman or Byzantine Emperors, but later found use in Anglo-Saxon illuminated manuscripts for the Emperors in Carolingian art and Ottonian art. The discovery of shell fragments in archaeological sites in Scotland and Ireland has pointed to the harvesting of sea snails for a gland which produces the purple colour. 

Figure 1: Fragment of the Codex Purpureus Petropolitanus, 6th century, Cotton MS Titus C XV, f. 4v. Read more about this codex on the BL Medieval blog: A Papyrus Puzzle and Some Purple Parchment. 

In 1992 marine shell remains were recovered from caves in Sutherland County in Scotland. Archaeologists used sieves to isolate shells of the whelk known scientifically as Buccinum undatum. These whelks survive in shallow water (down to about 100m) and are found in sand and mud. Their usual capture occurs using baskets or baited pots. The fragmented state of the shells dispersed around the site suggested that they had been purposely collected and broken.

Figure 2:  The sea snail Buccinum undatum.

Another type of whelk mollusc, known as Nucella lapillus (dogwhelk or Purpura lapillus) was found at the Scottish site in Wetweather Cave. Nucella lapillus are found in crevices around rocky shores and estuarine conditions. They are a species of predatory sea snail found around the coasts of Europe and in the north west Atlantic coast of North America where they feed on barnacles and mussels. The deliberately broken shells indicated to researchers that the whelks, which are not edible and were not being used as fishing bait, were being gathered for the production of purple dye.

Figure 3: Nucella lapillus feeding on barnacles. 

Nucella lapillus was also found in Connemara in the West of Ireland in 1919 by J. Wilfred Jackson. Heaps of shells (referred to as Purpura-mounds) had previously been found in 1895, but Jackson noted that the shells had deliberately broken apical whorls (a whorl being a turn of the whelk's spiral shell), but the lower whorl with the mouth had been left intact. The shells were smashed in such a way as to retain the cumella allowing the beast to be removed easily. It was clearly a serious business with one of the Irish Purpura-mounds measuring about 50 by 14 m  - over 200 whelks were found in a single square foot!

The dye is comprised of a mucous secretion from the sea snail's hypobranchial gland and is an organic compound of bromine. The secreted fluid is released by the sea snail as a defence mechanism when agitated. The secretion can be collected by "milking" the sea snails, however this is a very labour intensive process and more often than not the snails are crushed instead. It can take thousands of snails to produce a single gram of pure dye. After salting, boiling and sitting for a few days the gland fluid begins to turn from a pale cream to a purple colour. This process is accelerated by sun exposure. After about 10 days the dye is ready for use.

Figure 4: A purple parchment page of the 6th century Codex Argenteus with gold and silver lettering. 

Christina Duffy  (@DuffyChristina)

Further reading

Pollard, Tony (2005) 'The excavation of four caves in the Geodha Smoo near Durness, Sutherland'. Scottish Archaeology Internet Report 18

Jackson, J.W. (1917) 'Shells as Evidence of the Migrations of Early Culture'

Henderson, George, Vision and Image in Early Christian England, Cambridge University Press, 1999, paperback edition 2010, Chapter 3, pp.122-135, 'The Colour Purple: A Late Antique Phenomenon and its Anglo-Saxon Reflexes'.