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Conservator analysing text lines on a Codex leaf.
Conservator analysing text lines on a Codex leaf.

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Overview of the conservation of Codex Sinaiticus at the British Library

Helen Shenton

Chair, Conservation Working Party

Introduction to the conservation of Codex Sinaiticus for all four sites

Codex Sinaiticus is the earliest manuscript of the complete New Testament and the earliest and best witness for several books of the Old Testament. For scholars of the Bible it is the pre-eminent manuscript, known as aleph or 01, in other words number one. The Bible was written by hand on parchment in the middle of the fourth century around the time of Constantine the Great.

About 400 leaves of the Codex remain, divided between the four locations. There are 347 leaves in the British Library in London; 43 leaves in Leipzig University Library; five fragments in the National Library of Russia in St Petersburg and 12 leaves and 45 fragments in St Catherine's Monastery in Egypt.

A key component of Codex Sinaiticus digitisation project is the Conservation Working Party, established with representatives from the four locations of the National Library of Russia, Leipzig University Library, St Catherine's Monastery and the British Library.

The main reason for the conservation element of Codex Sinaiticus project was to make sure that the leaves were all in a stable enough state so that they could undergo the process of digitisation without being harmed. The principle was to carry out only sufficient conservation of the leaves to stabilise them for imaging.

In order to know how much conservation was required, the condition of each of the leaves needed examining and documenting. A way of recording the condition was designed that could be used in all four locations. This information would be incorporated into the individual digitised images of leaves on the website. The conservation assessment has led to an internationally-agreed new terminology for some of the special physical features of the manuscript and has produced a model for conservators and scholars to identify these terms.

The leaves have been in different physical and climactic environments and are in different condition; for example, the parchment exhibits different amounts of cockling and there are degrees of corrosion from ink. One of the original aims of the conservation assessment was to link the current condition to the "life" that the leaves have had in the different locations. Reviews of any previous repairs and conservation were undertaken where possible. A future ambition is to review the environments in which the leaves have been variously kept (though the experience of other research projects such as the "Identical Books Project" suggest that detailed historic environmental records will rarely be available and potentially link them to the condition of the different components of the manuscript.

The project aimed to carry out an unrivalled, detailed examination of the physical characteristics of the manuscript to help identify who wrote the manuscript and where it may have been written. Therefore, elements such as the different inks, the way the leaves were prepared for writing and the type of animal from which the parchment was made were investigated. The conservators carried out a very close visual inspection leaf by leaf or fragment by fragment in each of the four sites.

For specific questions, a combination of "high-tech" and "low-tech" methods was used. For example, a technique adapted from diagnosing cancer using ultra violet and infra red light was explored for looking at the composition of the ink and areas where the writing has been corrected. DNA techniques were investigated for their potential to identify the type of animal from which the parchment was made (the one reference by Tischendorf was the "antelope"). Ultimately, international experts were asked to look at the parchment under high magnification and give their expert opinion about the species of animal.

Collaboration and consultation

The international co-operation of the project has been a very important element, further broadened by linking to conservation and research projects around the world. The principle for all the analysis and examination was to use non-invasive, non-destructive techniques.

The working method was to be inter-disciplinary across Codex Sinaiticus project and to be collaborative with other international projects. There was extensive consultation between scholars and conservators to define what curatorial and codicological questions could also be addressed during the extensive and intensive examination and subsequent documentation of the manuscript (undertaken primarily to assess the condition and need for conservation prior to digitisation). There were some fundamental questions that needed information, for example, work on the composition of the inks might assist with the identification of the different scribes.

This led to a very inter-disciplinary approach involving recording over 300 fields of information, documenting everything from the characteristics of the parchment such as the follicle patterns (as an aid to identification of animal type) and colour (using international colour standards) to codicological features such as pricking and ruling and marks on the fore-edge of the central bi-folium of quires which became known as "squiggles".

Similarly, there was extensive consultation between the digitisation experts and conservators about the imaging, from the practicalities of minimising risk and the design of book cradles to the achievability of UV and IR imaging.

The collaborative nature of the Conservation Working Party meant that the partners agreed to use the same documentation. It was developed in English with hypertext links to images of features, for example, erasures, over-writing and offsetting of the ink; distortion and creasing of the parchment and previous repairs. It was further translated into German, Greek and Russian. The information entered onto the spreadsheet has then been transposed onto the digitised leaves on the website.

Moreover, the collaborative nature extended beyond the four partners into working with other established projects. For example, the requirement for systematic, reproducible measurement and comparative documentation of the parchment linked into the work of the EU-funded IDAP network Improved Damage Assessment of Parchment.

Archival records of previous conservation were reviewed where possible and the physical evidence of previous conservation was recorded during the examination.

Conservation for Codex Sinaiticus Project at the British Library

The working principles of the conservation-related work undertaken at the British Library were to:

  • Minimise the risk to the manuscript, for example, by minimising the handling of the original manuscript.
  • Minimise the amount of imaging, for example, by carrying out raking light and standard light imaging (and possibly UV) at the same time.
  • Carry out only non-invasive, non-destructive analysis.
  • Collaborate with relevant research projects.
  • Document the work for future researchers.

The different elements of the project were:

  1. Pre-conservation; previous conservation and binding
    • Research records of acquisition, exhibition and storage history from library archives and catalogues, from Douglas Cockerell's archive and secondary sources.
    • Research previous conservation and 1935 binding.
  2. Assess Conservation techniques
    • Review other comparable projects and professional initiatives.
    • Review potential treatments for example, of iron gall ink on parchment.
    • Produce bibliography.
  3. Assess Analytical techniques
    • Review ink identification methods.
    • Review parchment identification methods.
  4. Carry out Conservation assessment and documentation
    • Design and pilot the documentation.
    • Establish data recording protocols to ensure consistency across partners.
    • Record the evidence of scribal hands.
    • Examine scribal corrections.
    • Examine the inks.
    • Record codicological information for example ruling and pricking .
    • Establish identification of the type of parchment.
    • Assess condition and conservation treatment.
  5. Produce protocols for imaging
    • Environmental conditions.
    • Investigation of cradle system.
    • Investigation of light levels and heat emission; establishment of appropriate UV wavelengths for analytical images etc.
  6. Conservation treatment
    • Review available techniques.
    • Carry out conservation.
  7. Dissemination
    • Documentation findings onto website images of leaves.
    • Write papers; input to Exhibition; film treatment.
  8. Identify outstanding issues and areas for further research

The project

The examination of the 347 leaves of Codex Sinaiticus at the British Library was a major undertaking and afforded the conservators an unrivalled opportunity to observe all the leaves during a condensed timeframe. The following essays on the website have been written based on observations made during the condition assessment and conservation treatment:

Conservation treatment

The 347 leaves of Codex Sinaiticus at the British Library were conserved and bound into two volumes in 1935 by Douglas Cockerell. They arrived at the British Museum Library in December 1933 from St Petersburg, as unbound conjoint bifolia in a metal box. Cockerell carried out some treatment of the parchment and resewed the leaves into two volumes with oak boards and white alum tawed cape goat spines. The first task of the current Conservation project was to research the history of the manuscript since its arrival in the UK, using British Library archives and the Douglas Cockerell Archive. These included correspondence between Cockerell and the British Museum, his Time Book for Work on Codex Sinaiticus, lists of materials and suppliers, and his reports on the "Repairing and Binding Codex Sinaiticus at the British Museum. The correspondence sheds light on the decision-making involved in the rebinding of Codex Sinaiticus and illuminates especially, Cockerell's approach to the project regarding documentation, choice of materials and techniques. It also gives some insight into the discussions by the Trustees and the level of public interest. The correspondence reveals a high level of goodwill on the part of suppliers in helping Cockerell. In 1952, Roger Powell conducted a brief assessment of Codex Sinaiticus and the Archive contains his letter to Cockerell, outlining his view that it is Substantially … in very good order" with, for example, some lifting of the repairs to the parchment.

Summary of documentation

The current conservation condition assessment was carried out in a very methodical method, after extensive discussion and consultation. Existing documentation models were incorporated where appropriate. For example, elements of the survey methodology and terminology of the St Catherine's Foundation Conservation project developed for printed books were used, together with discussions with Christopher Clarkson. Secondly, elements of the National Preservation Office's Preservation Needs Assessment and a further refined BL condition survey methodology were used, especially for descriptions of damage.

The partners agreed to use the same documentation, recognising that it was best suited for the leaves and less suited for the fragments. The hypertext links to images of features of the ink, parchment surface etc are taken from examples found on Codex Sinaiticus. Whilst it has been translated into German, Greek and Russian, it was found to be most consistent to complete the assessment in English and then translate the findings. Created originally as a spreadsheet to aid search and analyse the information more easily, the information has since been transposed onto each digitised leaf on the website for future researchers to interrogate and interpret.

A very extensive glossary was produced of the terms used to document Codex Sinaiticus. These have been incorporated into the images on the website. Hypertext images of the terms were also produced, which again are embedded in the presentation of the leaves on the website.

All the physical aspects of the manuscript are recorded for both short-term and long-term purposes. The short-term purpose was to assess the stability of the manuscript before digitisation and determine what conservation is required. Longer term, the manuscript can be monitored given the potential repeatability of the documentation.

The codex was examined and documented under a series of headings, working logically from the primary support outwards:

  • the parchment
  • scribal features
  • codicology
  • previous treatment
  • condition
  • condition of previous repairs
  • conservation treatment

These were further refined, for example, each parchment leaf was documented as to whether it was the hair or flesh side of the animal, whether there were follicle patterns and axilla marks, skeletal marks, scars and veining. These features help to identify how the parchment was prepared and help identify the type of animal the parchment was made from.

A series of features record evidence of the parchment-making process, for example, parchment-makers' holes and repairs, or the striations left by the knife used to scrape the parchment.

A further series records the characteristics of the parchment now, its thickness, opacity, colour, surface (whether glossy, satin or matt). The method used is recorded in the glossary, for example, measurements of the thickness were taken with a micrometer at seven locations to determine uniformity and the average between the thinnest and the thickest were also calculated. The condition is recorded by damage type and extent for example surface dirt, accretions, major or minor cocking, which builds on survey methodologies used in museums.

Collaboration and analysis

A conservation checklist was produced for the technical working party, outlining the characteristics which should be noted during the imaging. These included:

  • very fine text (where the character height is less than 2mm)
  • text that extends or originates in the gutter
  • text that has "burned" through the parchment
  • ruling, pricking and other outline marks
  • faded text, offset text
  • extensive and/or deep creasing (more than 5mm)
  • repairs.

An investigation and evaluation of multi-spectral imaging was carried out as part of the project, as a potential method of revealing, for example, erasures or over-written passages. By examining a manuscript in different regions of the visible spectrum (from UV to IR) differently-coloured features may be distinguished. In the event, the images taken with UV light to reveal passages identified by the curators and transcribers as being particularly interesting were of such high quality that the hyperspectral imaging was used less than originally envisaged.

Investigations were made into how to identify the animal from which parchment was made. Tischendorf mentions antelope3. The type of animal could help identify where the parchment was made and/or where the manuscript was written. DNA has been used in some manuscripts but it is a technique which requires about a square centimeter of parchment, and one of the governing principals of the project was there would be no destructive testing. The usual way to identify animal skin is to examine the follicle patterns, which are distinctive for each species. However, the there was gelatinisation of the parchment and distortion from stretching which made this examination of follicle patterns difficult. An expert was consulted and sent some 65 images which he examined microscopically and reported that "Most positive identifications are calf, but a few wool sheep has also been found. In most cases are found gelatine [is found] formed in the follicles".


The principle was to carry out only sufficient conservation of the leaves to stabilise them for imaging. Following the extensive condition assessment, a minimal amount of treatment was required to stabilise Codex Sinaiticus to enable the manuscript to be digitised.

The principals determining the choice of materials and techniques were that they should use the minimum amount of moisture; that the repairs and supports should be strong but not place any strain on the Codex's very thin parchment; and the repairs should blend into the substrate and can be safely removed if necessary.

Some of Cockerell's previous parchment repairs were lifting and these were reattached using an application of 5% Salianski Isinglass in 95% deionised water. Isinglass adhesive was selected due to its "tacky" properties, its ease of removal and its ability to adhere at room temperature.

Small tears located on the outer edges and within the margins away from the text were repaired using a remoistenable, light weight (11gsm) Tengujo Japanese tissue, which had been pre-coated with two applications of 5% Salianski Isinglass/95% deionised water.

Any weak areas within the text columns were supported with small "splints" prepared from long fibred Japanese tissue. A suitable coloured Kozo tissue was blended into a pulp and kept in small pulp balls awaiting use. When required, the long fibres were teased out into splints with tweezers. The 5% Isinglass/95% deionised water was then applied and the splint was placed between the individual text lines and characters. No adhesive or tissue fibres were placed in contact with the written text.

Conclusion: Key findings of the conservation project

The key findings of the British Library's element of the conservation are:

Conservation Treatment

  • Relatively little conservation treatment was required to stabilise the leaves to enable digitisation to be undertaken.
  • Apart from some ink corrosion, most of the leaves had only small tears and losses along the head, tail, fore-edge and spine, probably attributable to mechanical damage.


  • For the most part, definitive skeletal evidence was scarce. This led to the conclusion that, with a few exceptions, each parchment bi-folium was cut from a flank of the animal skin well away from the spine, neck and pelvic regions.
  • Much of the visual parchment evidence cannot answer many of the questions asked by those seeking proof about the origins of the Codex and the story of its survival. It does however inform the question about the animal type and is indicative of the fineness in the parchment that the animals' skins produced and the finesse of the workers who created it.
  • The parchment is:
    • Both bovine (calf) and ovine (wool sheep) in origin.
    • Exceptionally uniform in thinness.
    • Supple and flexible in quality.
    • Generous in bi-folio size and lavish in layout.
    • Characterised by a sparse quantity of visual imperfections and blemishes.
  • The parchment features reflect:
    • A well resourced enterprise.
    • The idea of excellence in the animal husbandry.
    • High standards in the selection of skins.
    • High degree of manufacturing finesse.
  • The parchment condition is:
    • Exceptional for its age.
    • Low in levels of significant degradation.
    • Affected by long-term ink corrosion.
    • There is gelatinisation of the parchment
  • It is the intention of the conservators to continue the analysis of the parchment features. It is hoped that with the availability of all the documentation data, it can then be used to compare the differences in folios across all holding sites and to help draw some further conclusions. There has already been some work done on stain mapping consecutive folios that are in different locations and these will also be compared for differences in colour and dimension in the hope that any disparity can answer some of the questions that still remain.


  • The visual examination carried out on Codex Sinaiticus has highlighted areas of conservation and curatorial interest.
  • Brown-black inks:
    • There have been two, possibly three, re-tracings of the brown ink text.
    • Some squiggles have been retraced.
    • Some of the primary quire numbers (on the Old Testament only) have been retraced in the past.
  • Red inks:
    • The red text has been retraced once or maybe twice.
    • The cause for the retracing is apparently not because of fading, but a characteristic of the ink solution prepared.
  • Quality of the inks:
    • The primary ink is of very good quality as no major degradation is visible.
    • The ink of the secondary retracing is of an inferior quality. It has caused ink loss, corrosion of the support and offset
  • Condition of old repairs on inked areas:
    • The silk gauze used by Douglas Cockerell is in good condition and is not apparently causing damage of the parchment or the inks.
    • Materials and techniques used by Douglas Cockerell for the repairs are very high quality.
  • Current condition of inks:
    • The inks are slightly friable but in overall good and stable condition.

Scribal Characteristics

  • Changes to scribal phenomena such as the location and spacing of text prickings and rulings did not appear to synchronise with Scribe changes as expected.


  • The restoration of the Codex carried out by Douglas Cockerell and his son saved many of the original features of the manuscript (such as book mark evidences remaining loops of threads and leather accretions on the fore edges).
  • Changes to scribal phenomena such as the location and spacing of text prickings and rulings did not appear to synchronise with Scribe changes as expected.
  • Thanks to Cockerell's accurate documentation and pictures it was possible to make hypotheses about previous sewing structures.
  • It is now conceivable to say that Codex Sinaiticus was never bound in two volumes as it is now.
  • That the text block edges were probably only trimmed once.
  • This was not done during the last sewing before the present one.
  • That was kept unbound at least for the last part of its life before coming to England.
  • That the previous binding was in a "Byzantine" style and that it was never sewn on supports as suggested by Douglas Cockerell.

Multi-spectral imaging

  • Multi-spectral imaging was chosen to complement the work done by the British Library's Imaging Services team, with the expectation that it would help to resolve dubious or ambiguous passages.
  • The intention was not to rival the systems used by the National Gallery and other institutions for high-resolution multi-spectral imaging of easel paintings, but to image small areas of the manuscript where the reading was uncertain.
  • The MuSIS, manufactured by Forth Photonics, met our requirements, producing images of adequate resolution for our purposes.
  • The MuSIS can produce reflectance spectra of the different inks used in the Codex, which can assist in identifying the pigments used. It is probable that the black ink is iron gall ink, and the red contains vermilion.
  • The digital images produced by the BL Imaging Services team were of such high quality that the scholars had no difficulty in transcribing even hard-to-read parts of the manuscript.

Areas for further research and analysis


  • Investigations on Codex Sinaiticus inks are ongoing, and more information is still to be discovered. It is hoped that it will be possible in the future to carry out scientific analysis using non-invasive in situ techniques, in order to confirm or modify current observations and theories.
  • Real time monitoring of the condition of the parchment to monitor change in condition over time, for example monitoring the gelatinisation from the JPEG2000 images.

Condition and environmental history

  • The correlation between the current condition of the manuscript, for example the degree of ink corrosion, and the history of the environmental conditions (if known) where the leaves have been variously housed, is an area for further work.


  • For the treatment of iron gall ink corrosion on a parchment substrate.


  • In order to have a better understanding about the manuscript's very complex and rich use (possible storage and its separated parts or unbound) a more accurate mapping of the stains could be extremely useful.