When describing the damage to and properties of parchment, visual observation is decisively important. During practical conservation, the visual description of the record is the first stem of documentation after the description of the cultural history.
When conducting visual observations, light sources of various wavelengths (ultraviolet 100-400 nm, infrared 770 nm-1 mm, visible valgus 380-770 nm) are used. In the case of visible light, observation in both direct and slanted light can help.
A good tool for practical conservation is an atlas of damages. The pictorial files of damage included in the atlas can be used by the conservator as templates for the damages that need to be identified. The terminology related to the damages added to the pictorial files, and the text explaining the possible causes of the damages simplify the documentation of the damage and the organization of the activities related to the conservation. The more samples of damage included in the atlas, the better tool it is. The information in this atlas of damages is the result of ca 4,000 visual observations of parchment.
Usually, one can visually identify several characteristic traits and/or injuries typical of a parchment. With the help of the atlas of damages, they can be documented in a coded way and with a text that characterizes the injuries in an unambiguous way. The atlas of damages can also help to document the injuries by specifying the locations thereof on the parchment. See the example below.
Visually identifying damage based on parchment document AMD 115.2.1:
Kahjustus: C 6.7 Helvestumine. Irdumine
Kahjustus; B 3.4 Joonimine
Kahjustus: C 6.5 Tindikadu. Luitumine, valastumine
Kahjustus: C 6.2 Klaasjas ala
Kahjustus: A 1.2 Jäsemete ala
Kahjustus: A 2.6 Paksuse kõikumine
When the type of damage has been determined with the help of the atlas, in the second stage of the documentation, it is possible to further study the damages by further visualizing them at the microscopic (0.001–0.1 mm), mesoscopic (0.05–0.1 µm) or nanoscopic (6–7.5 nm) level. Such examinations provide additional information about the nature of the parchment and the damage at the collagen fiber level. When planning further examination of the damages to the parchment, it is useful to keep in mind that analytical methods for determined damaging, unlike visual observation, may be harmful to the parchment.
Therefore, when planning further examinations, one should first ascertain,
- Whether damaging the document in the name of the established goal is ethical and
- Whether the results of analyses that will damage the document will significantly help to preserve the document as compared to not taking the necessary samples.
When planning to carry our harmful examinations, a compromise solution is to damage the document minimally and ensuring the repeatability of the obtained research results, along with an unequivocal interpretation that can be used to describe the damage and organize preservation in the future. Unfortunately, in the case of historical parchment, the repeatability of the research and the unequivocal interpretation of the results is complicated by a whole series of objective reasons. (K. Nielsen, Visual Damage Assessment. Improved Damage Assessment of Parchment (IDAP), pp. 45–51, 2007).
Every parchment document has totally different characteristics and damages, even if they are limited to a small area. The damages are not homogeneous throughout.
Individual micro samples that are taken do not fully characterize damage that covers a large area. It is necessary to methodically take micro samples from the places where damages have evenly occurred at a microscopic level. If this has not occurred, a significantly larger number of samples should be taken based on the principle of random selection, in order to statistically analyze them.
Whereas it is important that the most characteristic damage, that which most significantly impacts preservation, exists in the place where the micro samples are taken. This area is called the parchment’s specific damage area. When all these methodological preconditions are fulfilled, the repeatability of the research results is still the determinative factor.
The repeatability of results is especially poor in the case of the parchments, the different sides of which (avers, revers) have been processed differently and, based thereon, have been damaged differently.
In order to obtain repeatable research results, the micro samples should be taken from the parchments based on animal species. And the various skin structures that occur in the different areas of the animals’ bodies must also be kept in mind.
Based on the complicated methodology required for properly conducting research, the visual observation of the damage and status of the parchment acquires increasing importance in practical conservation. Whereas it is important that the visual observation methodology take into consideration the specific features of the parchment under examination and enable the determination of as much statistically analyzable information as possible.
In summary, the following is important when conducting visual observation
- Registering all the areas with specific damages;
- Grouping the damage areas based on their impact, formation or some other important similarity indicator; if possible, damage subgroups should be created during documentation;
- Making sure that the visual characteristics of the damage can be interpreted unambiguously;
- Making several measurements when testing/measuring visual characteristics and when analyzing, using the statistical average of these measurements;
- When registering whether characteristics exist or not, find additional information for describing the characteristic.
In addition to documenting the status of a document, a visual observation that is carefully thought-out and carried out document and analyze the regularity, connections and empirical patterns related to the appearance of damage and the reasons for its development.
In this atlas, parchment damages have been systematized into six basic types based on the causes.
- Damage that has been caused by the characteristics of the raw skin used to manufacture the parchment.
- Damage that has been caused by the manufacture of the parchment.
- The damage and characteristics of the parchment surface that were caused the final finishing of the parchment surface and the preparation of the parchment sheet for writing.
- Damage that was caused by formatting the parchment into documents, letters, book pages, etc.
- Changes caused by the repair or conservation of the parchment.
- Damage caused by storage or handling.
For a survey of the categories of damages and characteristics, along with the relevant terminology, see Register of parchment damage and characteristics [pdf].