Although the majority of historic manuscripts and drawings, made with iron-gall ink on paper, have survived over centuries in a surprisingly good condition, many artifacts do show ink corrosion damage to various degrees. Metamorfoze, the Dutch National Programme for the Preservation of Paper Heritage, supports archives and libraries to preserve their paper collections. Collection keepers are challenged to take action to prevent future ink corrosion damage that would result in loss of collection value. However, to assess the urgency of preventive measures in specific cases, no help was available sofar. In response to this need, researchers at the Netherlands Institute for Cultural Heritage developed a new on-line tool: the Ink Corrosion Prognosis (ICP) - Web Service. This software tool can be used to estimate the risk of ink corrosion. It assists collection keepers to identify artifacts at high risk, to outline conservation priorities and to decide on mitigation strategies that efficiently minimize the ink corrosion risk.
Iron-gall ink is an historic ink that has been used extensively for writing and drawing until the 20th century. Due to the presence of chemically aggressive components in the ink (iron and acid), manuscripts and drawings made with iron-gall ink, can over time show damage at and near the ink lines. This phenomenon is called ink corrosion. The observable effects of ink corrosion can be grouped into three types: 1) change of ink colour and opacity; 2) discolouration of paper areas besides and underneath the ink; 3) occurence of cracks and loss of fragments in the ink areas. In severe cases these changes lead to a loss of value.
As a first step in conservation decision making, conservators often describe the present condition of an artifact in a so-called condition report. A condition report typically does not indicate to what extent an artifact's condition is stable or will degenerate. Thus, the urgency of preventive action remains unclear. To answer this question, the future condition of the object needs to be predicted. In other words, a damage prognosis is required.
The development of ink corrosion damage for a specific object is understood to depend on a combination of object characteristics, environment, and time. In other words, two identical artifacts with similar object characteristics, kept in different environments can show different damage. And, not all iron-gall ink artifacts stored in the same environment will develop ink corrosion to a similar degree.
Object characteristics used for the iron-gall ink prognosis are object age and color distribution functions of front and back image. From these characteristics we deduce the expected rate of change and the decay pattern. Environmental factors enhancing the development of ink corrosion are: 1) the exposure to high humidity levels, and 2) exposure to mechanical stress, typically due to handling. The Ink Corrosion Prognosis Web Service provides our best estimate of how your iron gall ink artifact(s) will look like in 100 years time.
The composition of historic iron gall inks is known to vary considerably. For our prognosis however, we assume all iron gall inks to be inherently corrosive. So, why are so different intensities of ink corrosion observed, even within a single artifact? Ink corrosion intensity depends on the penetration depth of ink into the paper. Areas where ink deeply penetrated, develop stronger ink corrosion damage than areas where ink remains on the paper surface, because the chemical activity of the ink is confined to regions where ink and paper are in contact. Deeply penetrated ink areas are found in particular in papers that are thin or insufficiently sized, contain ink on both sides, or show large dense ink applications. If suffient amounts of sound paper are present below the ink, both color and strength remain unaffected. Being confined to ink regions, in most cases the typical development of ink corrosion has only limited implications with respect to readability. However, unfavourable environmental conditions can dramatically alter this prospect.
Exposure to high humidity levels results in a criticially high moisture content of the paper. This will affect ink corrosion because moisture causes detrimental ink components to spread and penetrate further into previously sound paper areas. Over time these parts will discolour. The embrittlement of ink/paper regions, accompanying color changes, is not visible as such. Exposure to mechanical stress, typically due to handling, will cause the formation of cracks in brittle regions. Continued handling will cause further crack formation and eventually lead to loss of fragments.
Because exposure to high moisture and high mechanical stress levels can significantly enhance ink corrosion damage, a reliable prognosis can not be made without assessing the artifact's likely future exposure to both risk agents. Moisture exposure levels are considered high if within the next 100 years there is a significant chance (10%) of reaching a critical moisture content within the artifact. This occurs as a result of equilibration with high relative humidity levels or direct wetting, for example due to humid storage conditions, during water leakage incidents, or caused by unsafe wet/humid conservation treatments. We consider relative humidity levels arising above 70% to be increasingly dangerous with a maximum risk level at saturation. Mechanical stress exposure levels are considered high, if within the next 100 years, parts of the paper containing ink are folded or severely bend at least 10 times during consultations. Combining both environmental factors we now distinguish four different ink corrosion scenario's (A-D):
|- Ink Corrosion Scenario A:||100 years|
|- Ink Corrosion Scenario B:||100 years + intensive handling|
|- Ink Corrosion Scenario C:||100 years + high moisture|
|- Ink Corrosion Scenario D:||100 years + intensive handling + high moisture|
How will your iron-gall ink manuscript or drawing look like in 100 years time? To obtain a visual prognosis for your artifact, you can use the web form below to upload images of front and back of a single page to the Ink Corrosion Prognosis - Web Service. You are asked to specify the artifact's future environment by choosing an ink corrosion scenario (A,B,C or D) and you will have to estimate it's year of creation. For reference purposes you can also add artifact meta data and user details. After uploading and image processing done by our ICP server, an Ink Corrosion Prognosis Report will appear in your web browser. The report will contain a virtual image representing our 100 year prognosis of ink corrosion damage for the specified ink corrosion scenario. For reasons of comparison, the prognosis report also contains images of corrosion damage for the other three ink corrosion scenario's that do not apply to your artifact.
The Ink Corrosion Prognosis - Web Service can only estimate the risk of ink corrosion damage for artifacts with iron gall ink on paper. This tool can not be used for other support materials (e.g. parchment), not for other inks (e.g. printing inks), and not to estimate other risks (e.g. fire risk). If you are not sure if your object contains iron gall ink, you can apply a micro-chemical test for iron(II)ions. For test details see The Ink Corrosion Website.
Although a visual damage prognosis is informative, as such it can not tell you whether to take action or to accept these predicted changes. The question now is: How important are these changes? Or, how much value will be lost? The answer to that question in principle depends on the (anticipated) function of your artifact. Is it a Michelangelo drawing that the institution is likely to exhibit frequently within the next century? Or is it a manuscript that is primarily valued by historians for it's textual information? Although a general rule cannot be formulated, in the context of archives, the readability function of artifacts probably outweighs other aspects. For this reason we supply with the ink corrosion prognosis a numerical estimate of readability loss. This number summarizes loss of textual information due to both color change and loss of fragments.
To obtain a reliable prognosis, your uploaded artifact images need to meet a number of requirements:
To create an ink corrosion prognosis report for your artifact use the web form below.
Please try again later to click the button to upload and create your ink corrosion prognosis report or here to see to see an example report.
Your images and other information uploaded here are considered confidential. They will be stored to analyze and improve this web service only and will not be distributed to third parties.
Do you want to know more about history and preservation of iron gall ink manuscripts and drawings? Browse to THE INK CORROSION WEBSITE. Current link: ECPA . Future link: ICN .
The Ink Corrosion Prognosis Web Service has been developed by Frank Ligterink (ICN), Birgit Reissland (ICN), Norbert Ligterink (consultancy), and Claire Phan-Tan-Luu (University of Paris I-Sorbonne).
Development and hosting of this web service is generously funded by Metamorfoze, the Dutch National Programme for the Preservation of Paper Heritage. This project is a contribution to the joint paper conservation research program of three Dutch national institutions: Instituut Collectie Nederland(ICN), Nationaal Archief (NA) and Koninklijke Bibliotheek (KB), coordinated by Bureau Metamorfoze. Webhosting and technical advise is provided by Chaos Internet Solutions. We are thankfull to the Zeeuws Archief Middelburg and the University Library Leiden for providing research material. This project would not have been possible without the many invaluable discussions with national and international collegues...
You are encouraged to use the Ink Corrosion Prognosis Web Service to improve your conservation strategy planning. Please don't stop thinking after downloading your report! Although great effort is made to provide you with a reliable and usefull web service, the information provided through this website can be inaccurate or simply wrong. Prognosis results for your specific objects are possibly incorrect. The Netherlands Institute for Cultural Heritage does not accept any liability for damages of any kind resulting from the use of this website.