Multiple maps and map overlays from HO193/75, showing signs of mechanical damage

Transparent papers are present in The National Archives' collection as maps, map overlays, artistic designs and engineering plans. The transparency of the paper is vital for the record to fulfil its intended function. Unfortunately, many of these records are in poor condition (frequently showing tears, holes, creases and folds), they are brittle and discoloured resulting from the methods of production of the transparent paper coupled with the heavy handling that often occurred if the records were working documents.

Treatment on a case-by-case basis

In many cases the condition of the transparent papers requires some form of conservation treatment to ensure that the records can be handled without undergoing further degradation. However, this is complicated by the wide variation in the condition of transparent papers, their susceptibility to damage by water or solvents that can be used in conservation treatments, and their dispersal throughout the collection. Many treatment options ranging from minimal to full-scale treatment are available, allowing the tailoring of the treatments to the specific record.

Each transparent paper must be considered individually as the treatment for one may not be suitable for another, particularly as the manufacturing process of the papers can greatly affect the stability of the paper with respect to water and solvents. However, for institutions such as The National Archives where full-scale treatment of all transparent paper documents is not a viable option for the reasons mentioned above, the question of when a transparent paper should be treated, and to what extent, is very significant. The absence of an answer to this question in the context of The National Archives was addressed in a one-year fellowship, which began in October 2012.

Conservation Research Fellowship

This fellowship aimed to deliver practical tools that aid conservation professionals in deciding if, how, and when transparent papers should undergo conservation treatment or rehousing. Working with colleagues from across The National Archives and experts from other cultural heritage organisations, we have developed a decision framework that summarises the factors and questions to be considered when deciding if a transparent paper should undergo conservation treatment. We have also developed five tools to support this framework:

  • The Transparent Paper Survey for Readers and Conservators - this survey ran for 12 months in the reading rooms and conservation studios of The National Archives. The survey was successful at gathering valuable data with minimal staff input. Consequently, the survey method may be adapted for use in future projects. The survey results, some of which have been reported on The National Archives' blog, provided much needed evidence about the location and condition of transparent papers in the collection
  • The Transparent Paper Database - this database stores information about transparent papers such as location, condition, and size, that can inform preservation planning and will in time provide a comprehensive overview of these papers in the collection
  • The Condition Rating Scale - this scale can be used to indicate the extent and severity of damage types such as tears, folds, and fragmentation, to help evaluate the condition of the collection and prioritise records for treatment
  • The Colour Rating Scale - The scale can be used to indicate the colour of transparent papers which can vary from white to shades of yellow, orange, and brown. We are investigating whether the colour is a reliable indicator of the method of manufacture since this can affect preservation decision-making
  • The Treatment/Rehousing Decision-Tree - this decision-tree builds on a conservation professional's existing knowledge and skills to decide how to treat or rehouse a transparent paper and to identify those records that would benefit from future treatment or rehousing

Publication of this framework and its five tools is underway. If you would like further information on this fellowship, please email