For the proper care of an art collection you should be aware of the agents of deterioration in order to avoid or minimize their effects through the implementation of a number of simple procedures. Agents of deterioration are external forces that act upon objects and cause their chemical or physical degradation. They may include some of the following: direct physical forces; theft, vandalism or careless transportation of the objects; fire; water; pests; pollutants; light levels; incorrect relative humidity and temperature.
DIRECT PHYSICAL FORCES
Responsible for various types of damage that can deform, puncture, dent, scratch and/or cause wear to all types of objects. These damages are generally related to improper handling, transportation and exhibition of the objects or, in rarer but more severe cases, catastrophic causes such as the collapse of a shelf or part of a structure of the building, earthquake, etc.
Accidents have happened in many different situations, for example during an exhibition opening, when a champagne cork went flying through a canvas painting, leaving a hole in its wake. A crated painting shipped to an exhibition was pierced by the forklift truck that was supposed to safely transport it from the airplane to the cargo area. Heard of the Qing dynasty vases shattered by a visitor to the Fitzwilliam museum as he fell down the staircase? Or what about the 19th Century statue that was broken by a student while trying to take a selfie?
Recommendations
- Provide secure packing to minimise potential damages during transport by providing cushioning and protection;
- Whenever possible resort to specialized art handler's carriers for highly valuable or fragile items;
- Be aware of the risks involved with large numbers of visitors and secure your collection if it is on open display.
THEFT AND VANDALISM
May be intentional (theft of objects easy to carry, vandalism) or involuntary (misplaced or lost objects). Even the most famous museums have had high-profile thefts, so this should not be underestimated. There have been numerous famous cases of vandalism to works of art, including spray painting of a Picasso, graffiti to a Mark Rothko at the Tate Modern, and countless others. Rembrandt’s Night Watch at the Rijksmuseum in Amsterdam was repeatedly slashed with a knife, while a sketch by Leonardo da Vinci in the National Gallery, London was shot at with a gun, resulting in severe damage.
Recommendations
- Photograph and inventory the objects and update the inventory regularly;
- Periodically check the locks of the outside and inside doors;
- Plan a round of inspection frequently/daily;
- Install outdoor lighting;
- Install security cameras, burglar alarms or employ security guards.
FIRE
Causes total or partial destruction of the works, chars, and leaves soot deposits and smoke residue.
Recommendations
- Periodically check electrical installations and existing air conditioning systems, no matter how sophisticated they are;
- Install an automatic fire detection and sprinkler system. Where this is not feasible, implement minimal measures of fire fighting, including the installation of fire extinguishers, fire blankets and other means such as sand buckets, for example.
WATER
Water poses a grave threat to objects and works of art, as it causes damage which may in some cases be irreversible: textiles (staining), metals (corroding), wood (swelling), stone (efflorescence) and paint layers (delaminating or buckling layers), for instance.
Recommendations
- Check for infiltration of rainwater or water from plumbing, broken or leaking pipes and flooding; remove all objects that may be affected immediately;
- Do not keep any objects directly in contact with the floor in order to protect them from possible flooding or leaks, as well as insects and mechanical shock;
- Air conditioning units have a tendency to leak – avoid hanging paintings directly underneath;
- Ensure windows are closed in case of heavy rainfall.
PESTS
These are biological agents that can cause damage to collections. They can be divided into three groups: vermin, insects and mould. Vermin may include birds or rodents that can gnaw at, or foul the objects with their excrement. Insects such as silverfish (paper), the common woodworm and termites (wood), and moths (textiles) cause progressive degradation in organic objects. This starts with small holes scattered throughout the object and may subsequently lead to severe loss of material, sometimes up to complete destruction. Mould can appear in various materials, such as paper, leather and wood, and can weaken or stain them (it is usually white or brown in appearance, often with a characteristic odour), preferably in the more hidden and less ventilated areas of the objects.
Recommendations
- Distribute insect traps throughout the storage and display area;
- Avoid food consumption around works of art, as crumbs provide a source of food for pests;
- Keep the storage area cool – cockroaches and many other insects prefer a warm environment, and will avoid your storage area if it is colder than the outdoors;
- Regularly check for insect frass and wood powder, which is a tell-tale sign of woodworm or termite infestation;
- Seal doors and windows;
- Keep objects that were recently acquired quarantined before putting them on display or in storage. This allows you to check for any possible infestation that might affect the remainder of your collection.
Figure 1. Side bar of a painting’s strainer attacked by insects (left photo)
and backing-board of a work on paper attacked by mould (right photo).
and backing-board of a work on paper attacked by mould (right photo).
POLLUTANTS
Source can be external (industrial sources, domestic, transport-related or the incineration of waste) or internal (linked to the presence of visitors, the exhibition and construction materials, etc.). This includes gases (such as ozone, formaldehyde, nitric acid, sulfur dioxide), liquids (such as plasticizers, grease), and solids (such as dust, soot) which can be responsible for changes in object processes that may include, among other things, the acceleration of the natural processes of ageing and degradation, discoloration, corrosion and disintegration.
Recommendations
- Leave windows closed, particularly during hazy periods, to avoid pollution from external sources affecting the collection;
- Filter the recirculating air of the air conditioner system and change filters periodically;
- Wash hands prior to handling objects, or wear non-slip gloves.
LIGHT LEVELS
Light degrades objects continuously and irreversibly. There are two types of radiation that are particularly harmful – ultraviolet radiation and visible light – since both can disintegrate, fade and darken organic and coloured inorganic materials.
Recommendations
- Use dim light, light only when needed and avoid heat resulting from the proximity of the light source to the object;
- Limit the lighting time so as to reduce the risk of fading/discoloration and accelerated ageing;
- Keep storage rooms in total darkness whenever they are not being used, and ensure extended completely dark periods for the most fragile objects by removing them from continuous display;
- When displaying the most sensitive objects (for example paper, textiles), natural light should be avoided. For less sensitive objects it will be possible to resort to natural light as long as it is controlled and filtered. The sun must not shine directly on the objects, and windows should be covered with UV-film, blinds and/or curtains.
TEMPERATURE AND RELATIVE HUMIDITY
High temperatures increase the rate of degradation. Fluctuations in humidity affect fragile objects in particular, while wood may expand and contract, resulting in cracks and warping.
Maintaining a dry and cool environment helps reduce the rate of deterioration of objects. Mould growth is a serious issue in the tropics, and can be avoided by maintaining an appropriate environment.
Recommendations
- Keep relative humidity and temperature below 60% and 24° C respectively, if possible;
- Avoid large and rapid fluctuations in temperature and humidity;
- Run air conditioning or fans to circulate air throughout the space;
- Install dehumidifiers if necessary;
- Purchase a digital thermohygrometer to be aware of the environmental conditions in your storage and exhibition space;
- Plastics, electronic and photographic materials are sensitive to high temperatures and benefit from colder storage environments;
- Do not hang paintings or place objects along outside walls (these can get cold and wet);
- Move objects away from sources of direct heat.
Figure 2. Example of a digital thermohygrometer
(which can be purchased for example on HERE)
(which can be purchased for example on HERE)