Assessing the condition of parchment


The idea to combine the assessment of the state of parchment documents with the digitization process developed at the Ennistuskojas Kanut (as of 2014, the Estonian Open Air Museum and Conservation Centre Kanut) in the course of the project between 2010 and 2012 to digitize the parchment documents from the 10th to 20th centuries in the Tallinn City Archive and Estonian History Museum. The same principles were also applied during the digitization of the parchments in the Tallinn City Archive that was carried out between 2013 and 2017. The idea was based on the following circumstances:

  1. Based on the logistics of the project, more than 5,500 parchments were brought to the Kanut digitization workplace during a short period of time. The condition of most of them had not been determined based on a definite methodology.
  2. In the course of the digitization, each of the parchments had to be handled separately, for both planning the digital preparation and for the digitization.

During this handling of Estonia’s oldest legacy of unique, handwritten parchments, it was logical that the conclusion was reached that the digitization workflow should be organized in such a way that made it possible to visually assess the condition of the parchments and the damages they had suffered simultaneously with the digitizing activities (and keeping to the project schedule).

The assessment of the condition and damage was preceded by becoming familiarized with the practices of Estonia and other countries.

The high technical level of the digitization, which allowed the atlas of damages to be compiled simultaneously with digitizing the overall views of the parchment, was of critical importance.

On the condition of the parchments

The preservation and practical conservation of a unique legacy is considerably simpler to organize if the general condition of the parchments and the entire collection is known.

In order to find the optimal solution necessary for preservation, a visual observation of the damage and documentation of the condition must first be conducted.

The physical integrity and durability of the parchment can be determined if we determine the condition of the parchment. Assessing the condition helps to describe and document the durability of the parchment using simple tools, and in the case of collections, to make a statistical analysis.

Analytically, stages or categories are used for the assessment of condition. The number of categories needed to assess the condition is something that should be agreed upon in advance. In each category, the condition must correspond to agreed-upon and visually clearly discernible criteria. In the case of manuscripts, the durability of the text must be considered in addition to the integrity of the object and damages to the parchment.

Different methodological approaches are necessary for determining the condition of one parchment and a collection of many parchments.

When assessing the condition of a single parchment, the individual damage is documented more thoroughly, whereas it is important to describe the damage that is characteristic of this particular parchment. In order to complete the assessment of damage, an additional study of the properties  (23.03.2016) in the area with the most representative damage is necessary.

When visually determining the condition of a large collection, it is most important to conduct a systematic and comparative visual observation based on a definite methodology. If 100% of the collection is not visually examined, then the amount that is must be representative of the entire collection. Systematic observation means that the criteria for the various categories or states of durability must be specifically defined and the documents that are in different conditions must be visually clearly distinguishable from each other. When conducting such a visual assessment, it is possible to divide the parchments in a collection in groups by the condition they are in. An analytical database related to parchment condition compiled in this way can be used successfully as base data for the statistical analysis of the condition of various collections. A similar methodological approach was used successfully between 1998 and 2006 during the joint project to preserve Estonia’s research libraries. (THULE, 23.03.2016).

The more analytical parameters a database contains, the more opportunities there are for analysis using various samples and finding optimal practical solutions.

Knowing the condition of a collection substantially simplifies the activities related to the preservation and practical conservation of the collection.

It is important to keep in mind that the visual determination of the condition is always of a static nature. It does not consider the possible changes in the properties of the parchment in the future, which will occur regardless of the time and environment. The potential accuracy of the assessment is higher if comparative assessments are made of the condition of the object based on an agreed upon methodology in the shortest possible time. No less important for the assessment is the involvement of trained experts and the immediate planning of activities for preservation and practical conservation.

Determining the condition

The following form the basis for determining the condition of the parchments:

  1. The Parchment Damage Report,

Improved Damage Assessment of Parchment, 4.2016).

  1. Subsequent IDAP-project instructions (Helpfile for the Parchment Damage Assessment Atlas, IDAP)
  2. Results of the various studies on handwritten parchment documents:
    Codex Sinaiticus (PDF, 23.03.2016);
    Bicchieri et al. Inside the Parchment (PDF, 23.03.2016);
    René Larsen , Dorte V. Poulsen, Marie Vest. Report on the Assessment and Survey of the Condition and Technique of the Vinland
  3. Map and the Bindings of the Tartar Relation and Speculum Historiale (PDF; 23.03.2016);
    Kennedy, C. J. The Structure of Collagen within Parchment. Restaurator, vol. 24 (2003), No 2, pp. 61–13.
  4. Work conducted in the National Archives: Conservation project Review of the National Archives activities 2005–2006 conducted between 2000 and 2006
  5. E. Keedus. Pärgamendikollektsiooni konserveerimine ja säilitamine Ajalooarhiivis. MA thesis. Tartu 2006 (PDF, 23.03.2016).

In most of the works, the four categories related to the condition of the parchment are visually discernible: undamaged, slightly damaged, damaged and severely damaged parchment. In addition, it has also been studied whether and to what extent the visually defined chemical and physical properties of the parchments can be divided into these four categories.

With the help of research related to materials, the physical properties of the documents belonging to four different categories related to the condition of the parchment have been defined: thickness, flexibility, transparency, etc.  As have the properties of parchment related to the level of collagen fiber (hydrothermal degradation and structural stability of the collagen) and fibrils (X-ray diffraction).

In most cases, the studies confirm that the parchment documents that were classified visually into the four categories also differed when it came to their physical and chemical properties. Therefore, research results confirmed that the visual differentiation of various conditions is possible and, this was even true despite the variance of the research results.  The reason for the variance of the results in the case of the IDAP jobs may also have the fact that an analysis was made of the results of projects that were conducted in different countries by very different people.

In some of the studies (R. Larsen, Molecular Damage of Parchment Studied by Amino Acid Analysis. Improved Damage Assessment of Parchment, IDAP, pp. 111–114, 2007), the properties showed smaller differentiation and greater variance in the case of those parchments that had been assigned to third (damaged) and fourth (severely damaged) categories. In other words, when visually assigning the condition into four categories, a greater error, or smaller differentiation, occurs when the parchments are assigned into the third and fourth categories.

Based on the fact that dividing the condition of parchments into four categories results in great variance, in this work, three categories have been used in the visual determinations: undamaged, slightly damaged and severely damaged parchment.

Categories of parchment condition

This chart presents the criteria for determining the physical condition of parchment (the IDAP criteria are indicated in parentheses as a comparison).

Category Example
First category

Undamaged and slightly damaged – the physical integrity of the parchment is undamaged or there is some small-scale damage. There are no glass-like layers or mold. The text is totally preserved. The document can be easily handled and the surface is uniformly flexible.

Undamaged — uniform, good condition with no visible damage over the parchment surface with only one, or a few smaller areas with minor visible damages.

First category
First category
Second category

The physical integrity of the damaged parchment is ruined. Tears, holes stains, mold and glass-like layers comprise less than 1/3 of the surface. There may be partially loss of the text and flexibility. Handling may be difficult.

Progressing visible damage on a larger part of the parchment and/or more minor areas with serious visible damage — biological, chemical and/or physical.

Second Category
Second Category
Third category

The parchment is severely damaged – physical damage, stains, mold and glass-like layers comprise more than 1/3 of the surface. The text is significantly damaged. The document is difficult to handle.

Progressing visible damage on most parts of the parchment and/or several minor areas with serious visible damages — biological, chemical and/or physical.

Third Category
Third Category
Identifying the glass-like layers

The condition of parchment is directly dependent on the degradation of the collagen fibers, and this is indicated by the glass-like layers in the parchment. If structural and chemical changes have significantly altered the surface of the parchment, this is easily discernible during visual observation. The relief of the surface, tonality, transparency and flexibility. These changes are caused by oxidation and hydrolysis the deterioration and shortening of the long (ca 300 nm) collagen molecules with hydrogen bonds, which have twisted into left-handed α-helixes. The weakening or total disappearance of the hydrogen bonds that stabilize the molecules increases the degree of freedom between the molecules. And this results in the initially ordered α-helix-shaped collagen molecule acquiring gelatin molecule structure that has an either partially or totally random orientation. The appearance of glass-like layers alludes directly to the reduction of the parchment’s physical strength and hydrothermal stability. The degradation process is called (either partial or total) gelatinization. This is often accompanied by the development of white calcite or gypsum precipitate on the surface of the parchment. A change in the axial packing method of the collagen molecules will quickly lead to collagen degradation at the molecular level.

In the case of historical parchments, the results of x-ray diffraction and 2D electrophoresis analysis (The Structure of Collagen within Parchment. By Craig J. Restaurator, vol. 24 (2003), No 2, pp. 61–134) allude to the severe degradation of the collagen already during the manufacturing phase. This is also confirmed by the results of other studies (Tim J. Wess. Changes in Collagen Structure: Drying, Dehydrothermal Treatment and Relation to Long-term Deterioration. Thermochimica Acta, 365 (2000), pp. 119–128; Craig J. Kennedy. Parchment Degradation Analyzed by X-ray Diffraction. Bio-and Material Cultures at Qumran, Israel, 2005).

Based on research results, a large portion of the historical parchments that have been examined to date can be included in the severely damaged category. Hence, in practical conservation it is important to differentiate between the damage caused by the manufacture of the parchment from the damage caused in the course of handling the documents.

Three categories of glass-like layers can be determined by visual observation: condition 1. – no glass-like layers appear; condition 2. – the glass-like layers cover less than 1/3 of the surface; condition 3. – the glass-like layers cover more than 1/3 of the surface.

Technical details related to the determination of the condition

Between 2010 and 2016, the damage and condition of ca 3,500 parchment documents from the Tallinn City Archive, and about 400 from the Estonian History Museum, which are dated between the 13th and 20th centuries, were visually determined. The works are unique because the collection of documents that was studied represents the almost 700-year history of the territory of Estonia as well as the manufacture of parchment.

The condition of the parchment was assessed in the course of a digitization project, and therefore, when determining the condition, the specificity of the project had to be taken into consideration: a tight schedule, and the digitization workflow. Along with the digitization it was possible to organize the complete visual examination of the documents, but it was not possible to conduct more detailed material research in order to characterize the damages.

Along with the visual assessment of the damage suffered by the individual parchments, it was also possible to visually assess the damage and condition of the collection being digitized. It was assumed that a database created as a result of the systematically conducted visual examination would provide help in analyzing the condition and pattern of damage on documents formatting in various centuries. For examples of the results, see Analysis of the Condition of the Parchment.

The condition of the parchments, the occurrence of glass-like layers and the types of damage were determined after the preparatory work necessary for the digitization (description, cleaning, stretching) and the digitization itself was completed. When determining the damage, in addition to direct light, both penetrating and slanted light was used.  Visually, 50 different types of damages and characteristics were identified. These are listed in the register of parchment damage and documented in the atlas of damages.

The methodological basis for the work was acquired from the experience, analysis and results of critical assessments derived from IDAP projects (449 parchments were analyzed).


In summary, it is important to know the following about determining the condition of parchment in the course of carrying out a digitization project

In the course of the project to digitize the parchment collection, it is technically possible to determine the damages and condition based on a previously compiled methodology.

Creating a database on the condition and damages adds great value to the results the digitization project.

The database on the condition and damages us an important tool for analysis, preservation and organizing the practical conservation.

The condition of objects and the damages would also be possible to determine in the course of digitizing other heritage collections. For instance, this would be possible during the digitization of photographic collections, if the work was methodically organized in advance and the methodology was approved by experts.