There are various causes of chemical deterioration.



Exposure to light or ultraviolet (UV) radiation fades and discolours papers, and the media on the paper (for example, ink). The higher the light intensity, the faster the deterioration.

Mould growing in humid conditions can consume and stain the materials on which it grows.

Paper brittleness and staining is caused by acid in the paper or the materials it is in contact with.

Interaction between the paper and the printing medium used can cause deterioration.  For example, iron gall ink is acidic and over time, can burn through paper on which it is written.

Physical deterioration includes:

• tears, dents, punctures, abrasions, and paper loss from handling and usage
• splits from folds and creases
• damage from insects and rodents eating paper and glue
• buckling and distortion from extreme temperature and relative humidity changes

Correct handling of flat paper items will aid their long-term preservation.

• Never allow food or drink near items.
• Wash your hands before handling objects, even if you will wear protective gloves.
• Use powder-free, close-fitting surgical gloves for handling fragile objects.
• Use a rigid support, such as piece of cardboard, to carry papers. This is especially important when you need to carry fragile and oversized papers over long distances.
• Use a flat-bed trolley to move oversized material.
• Separate artworks and documents with archival tissue to prevent abrasion and ink or adhesive transfer.
• Use pencil when working with artworks as ink can be difficult or impossible to remove.

Temperature and humidity

Stable conditions can reduce the deterioration of objects.

Wide changes can:

• physically stress records
• accelerate their deterioration

Aim for a storage area with stable conditions:

• temperature around 20°C
• relative humidity below 60%

If specialised storage is available, aim for:

• temperature between 18 and 20°C 
• relative humidity between 45 and 50%

Office air-conditioning generally operates between 21 and 23°C in temperate climates.

Air-conditioning is usually on during office hours, so temperature and relative humidity changes outside these times.

Mould growth can happen when the relative humidity is over 65% for a considerable period.

Lighting

Materials degrade faster when exposed to light, especially UV. Fluorescent tubes often emit a high level of UV.

Only turn on lighting when needed.

Storage areas shouldn't have windows. Any windows should have opaque curtains or blinds.

Pests

Insects and rodents cause damage by what they eat or leave behind.

To reduce the risk of damage by pests:

• don't eat in storage areas
• keep floors and the tops of shelves clean
• empty rubbish bins regularly
• check storage areas regularly for outbreaks of insects or rodents

Should a pest infestation occur, you may need to arrange baiting or fumigation.

Use properly cured powder-coated metal shelves to store paper records and files.

Use plan cabinets for flat storage of:

• maps
• plans
• large artworks, including prints, drawings, posters and watercolours

Label storage boxes and folders clearly to minimise handling.

Keep the storage area and facilities clean to discourage pests.

Unsealed wooden and particle board or MDF shelving can release harmful vapours. Replace where possible.

Paper products

Boxes, folders, wallets and paper cards protect paper-based items against:

• mechanical damage
• light
• dust
• changes in temperature and humidity

They also provide micro-environments to reduce changes in temperature and relative humidity.

Choose high-quality paper products for long-term storage.

Plastic

Some plastics are also suitable for paper record storage.

The plastic should be free of:

• plasticisers
• surface coatings
• other harmful chemicals

The most suitable plastic film is a form of polyester known as PET (sold as Mylar or Melinex).

Food grade polypropylene and polyethylene are acceptable low-cost alternatives.

Encapsulation

This is a storage method that uses a fitted stiff polyester sleeve to prevent handling pressure and abuse.

The item can be viewed without direct contact.

Hot lamination

This treatment is not recommended. Sticking the plastic sleeve to the original document or artwork is irreversible and leads to faster deterioration of the paper inside.