Preserving paper documents and artworks
This advice is for collection items such as:
- letters and certificates
- newspaper and magazine clippings
- prints and posters
- drawings, watercolours and paintings.
Paper-based materials can deteriorate chemically and physically. Some deteriorate because of their inherent properties, others as a result of poor storage or display conditions. Damage can be caused by poor handling practices. The media on paper-based objects, such as ink, watercolour or pencil can also degrade. While we cannot stop deterioration, we can influence the rate at which it happens.
Chemical deterioration includes:
- Fading and discolouration of papers and the media on the paper caused by exposure to light or ultraviolet (UV) radiation. Deterioration will occur more quickly when exposed to higher light intensity.
- Deterioration caused by mould attack that can develop in humid conditions; mould has the ability to consume and stain the materials on which it grows.
- Paper brittleness and staining caused by acid either in the paper or the material with which the paper is in contact.
- Deterioration caused by interaction between the paper and the printing medium used. Iron gall ink is acidic by nature and over time, can burn through the paper on which it is written.
- handling and use damage such as, tears, dents, punctures, abrasions, and paper losses
- folds and creases causing paper to split
- pest attack, caused by some insects and rodents for which paper and glues are a food source
- extreme temperature and relative humidity fluctuations that cause buckling and distortion.
Correct handling of flat paper items will aid their long-term preservation. The following procedures should be followed:
- Always handle with care.
- Never allow food or drink near items
- Have clean hands, even when wearing protective cotton or powder-free surgical gloves. If an object is particularly fragile close-fitting surgical gloves may be more appropriate.
- Use a rigid support, such as piece of cardboard when carrying papers. This is important where papers are oversized and fragile or need to be carried over long distances.
- A flat-bed trolley is useful for moving oversized material.
- Interleave artworks and documents with archival tissue to protect them from abrasion and ink or adhesive transfer from other items.
- When working with artworks, use pencil not ink. Pencil marks are readily removed, whereas inks can be difficult or impossible to remove.
Preservation and storage
If specialised storage is available then temperatures between 18 to 20 °C and at relative humidity between 45 to 50 per cent are desirable. Office air-conditioning generally operates between 21 and 23 °C in temperate climates. If these conditions are stable then the natural deterioration of the objects can be moderated. Wide fluctuations in conditions can physically stress records and accelerate their deterioration. Note that air-conditioning systems usually only operate during office hours, leading to a wider fluctuation of temperature and relative humidity at other times. At sustained relative humidities over about 65 per cent, mould growth can occur. It is recommended that you aim for a storage area with stable conditions, where the temperature is around 20 °C and the relative humidity remains below 60 per cent.
Corrugated board storage boxes can provide a convenient micro environment by buffering documents from the full effects of fluctuating humidity and temperature.
Materials degrade more quickly when exposed to light, especially ultraviolet (UV). Surprisingly, fluorescent tubes often emit a relatively high level of UV. Lighting should be turned on only when it is needed. Ideally, storage areas should have no windows. Where windows are present, they should be covered with opaque curtains or blinds.
Insects and rodents will cause damage through what they eat or leave behind. Reduce the chance that they will be attracted to record storage areas by following these recommendations:
- Do not eat in storage areas.
- Keep surfaces (floors, tops of shelves) clean.
- Empty rubbish bins regularly.
- Check storage areas regularly for outbreaks of insects or rodents. Should an infestation occur, baiting or fumigation may be necessary. Further advice is available on Integrated pest management.
Use properly cured powder-coat painted metal shelves for paper records and plan cabinets for flat storage of maps, plans and large artworks. Prints, drawings, posters and watercolours should be stored flat, while paper files are usually stored vertically. Clearly label storage boxes and folders to minimise unnecessary handling. The storage area and facilities should be clean to discourage pests. Unsealed wooden and particle board/MDF shelving can release harmful vapours and should be replaced where possible.
Simple archival enclosures such as boxes, folders, wallets and paper cards protect paper based items against mechanical damage, light and dust. They also provide micro-environments that reduce temperature and relative humidity fluctuations.
Choose a high-quality paper product for long-term storage. The Archives has established a list of local suppliers of archival materials. Some plastics are also suitable for paper record storage. The plastic should be free of plasticisers, surface coatings and other harmful chemicals. The most suitable plastic film is a form of polyester known as PET, which sells under the proprietary names Mylar or Melinex. Food grade polypropylene and polyethylene are acceptable lower cost alternatives.
Encapsulation is a method of storage that uses a close fitting stiff polyester sleeve to take the majority of handling pressure and abuse. It allows an item to be viewed in its housing without direct contact. Hot lamination where the plastic sleeve is adhered to the original documents and artworks is not recommended. This treatment is irreversible and will lead to the accelerated deterioration of the paper inside.
If you require further conservation advice on the storage and display of paper documents and artworks contact the Agency Service Centre.