The conservation of works on paper encompasses a wide range of media and materials, including maps, prints, drawings, watercolours, manuscripts or scrolls, graphic documents on parchment or papyrus and archival material.
Many photographic materials also have paper as a support and feature many of the same types of deterioration, although conservators often choose to specialise in one or the other, or both.
Causes of deterioration
Inherent to all paper-based objects is sensitivity to light, heat, and humidity. Paper conservators work to minimise damage to collections on paper by controlling light and environmental factors through correct storage and display.
Acidity (high levels of pH) may lead to yellowing, brittleness and other kinds of discolouration such as foxing. Different kinds of paper may contain different levels of acidity inherent in the manufacturing proccess, or may have been introduced to an adhesive or mount that is acidic, a factor that causes the material to become unstable.
Mould is a major concern for paper collections, thriving on even small amounts of moisture.
Other pests such as insects and rodents particularly enjoy eating organic cellulose material, along with dust, adhesives and sizes on paper objects that may contain animal-based glues.
When damage does occur, paper conservators use a variety of methods to halt deterioration, minimise the aesthetic distraction from damage on a work, and ensure the work can be handled, displayed, stored or digitised.
By researching the materials of a work, including the paper type, adhesive, media and any other materials used, paper conservators use their knowledge to make the most effective treatment decisions.
Treatments for books and paper objects often include dry cleaning to remove surface dirt. This might incorporate the use of smoke sponges, erasers, brushes and vacuum methods. Mould is often removed through brush-vacuuming. Wet cleaning techniques vary from using simple swabs with purified water, to buffer (pH neutral) solutions, to stronger chemicals to remove more stubborn adhesives or stains.
Backing removal is often required when paper objects have been adhered to a backing board or other object that is causing chemical or physical damage. This process involves mechanical scraping using tools designed to remove layers of a backing gradually in order to free the object.
Washing is similarly common for paper objects that are stained, covered in adhesive or highly acidic. Using a variety of methods, a paper conservator can isolate areas to clean or fully submerge paper objects in solutions that vary from purified water to buffered water in order to clean and return the paper to a neutral pH level.
Lining a paper object is necessary when it is very fragile, contains many tears and requires an extra support for display or handling. Using diluted starch paste, conservators coat the reverse side of a paper object and line it with a suitable conservation-grade paper chosen for its weight, texture and appearance. Paper objects that do not require lining but have tears are treated locally with fine Japanese tissue paper and starch paste.
AICCM has a Special Interest Group for those interested in the conservation of works on paper. Join this group, contribute to its activities, or speak to a specialist conservator. For more about photographic conservation see: Photographs, or the AICCM Special Interest Group for photograph conservation.