Elaborate Prof (Dr) Achal Pandya, Head Conservation Department, Indira Gandhi National Centre of Art, Dr Swayam Prakash Tripathi Project Associate (Conservation) Indira Gandhi National Centre of Art (IGNCA), New Delhi
Poor air quality inside museums is one of the main causes influencing the state of conservation of exhibits. Even if they are mostly placed in a controlled environment because of their construction materials, the exhibits can be very vulnerable to the influence of the internal microclimate. As a consequence, museum exhibits must be protected from potential negative effects. In order to prevent and stop the process of damage of the exhibits, monitoring the main parameters of the microclimate (especially temperature, humidity, and brightness) and keeping them in strict values is extremely important. The study focuses on monitoring and analysing temperature of air and walls, relative humidity (RH), CO2, brightness and particulate matters (PM), formaldehyde (HCHO), and total volatile organic compounds (TVOC). The studies show that this environment is potentially harmful to both exposed items and people. Therefore, the number of days in which the ideal conditions in terms of temperature and RH are met are quite few, the concentration of suspended particles, formaldehyde, and total volatile organic compounds often exceed the limit allowed by the international standards in force.
The results represent the basis for the development and implementation of strategies for long-term conservation of exhibits and to ensure a clean environment for employees, restorers and visitors.
Light
Light can cause damage to collections. The amount of damage is determined by the intensity and type of light, the time of exposure, and the natural resistance of the object’s components. Light damage is not only limited to fading, overexposure can also cause weakening, discoloration, yellowing and embrittlement. Damage caused by light exposure is both cumulative and irreversible.
Light damage can be mitigated by controlling the amount of total light exposure over time. When artifacts are placed on exhibition, steps should be taken to ensure that the light exposure is controlled, monitored, and recorded. Facsimiles may also be used to avoid overexposure of the original artifact. Objects that are not on exhibit should be kept in darkness.
Ultraviolet Radiation
Ultraviolet (UV) radiation is an invisible component of many light sources including sunlight, fluorescent lights, and traditional tungsten light bulbs. It contains more energy and is therefore more damaging than visible light.
Human eyes cannot detect UV, so filtering UV will not affect the visual experience except for on certain very specific materials. Many modern white papers also contain optical brighteners, which will make paper appear slightly whiter when UV is present, but this is not a significant difference.
Measuring Light and UV
Visible light and UV can be measured with a handheld light-meter or data-logger. Less accurate light measurements can be taken with a smartphone app. Light reading should be taken slightly in front of the actual object, carefully following the manufacturer’s directions. Visible light is measured in lux or foot-candles. One footcandle (fc) is equivalent to approximately 11 lux.
Ultraviolet is measured in microwatts per lumen (μW/lm), which describes the fraction of ultraviolet radiation in visible light. Because it is a ratio, the total UV will increase as the light levels increase, even as the ratio remains constant. The exposure of an artifact to light is a product of illumination level and time: Light level (lux) x Time (hours) = Exposure (lux hours)
Lighting Design Considerations
To have a successful lighting design, lighting designers have particular considerations that affect lighting on
space, objects, and purpose. Colour rendered, colour temperature, texture, form, viewing angles, layered
light and maintenance are all factors that contribute to the whole. An understanding of these factors allows the lighting designer to fuse lighting elements with an architectural designed space to create an effective and functional design for humans to interests and experience the space. Pollution in the Museum Gaseous pollutants, including organic acids, sulphur dioxide, nitrogen oxides and ozone, can cause bleaching, discoloration and weakening of a variety of materials.
Particulate pollution (dust) can become embedded in the object’s surface, cause abrasion and wear, attract moisture, act as a food source for pests and be visually disfiguring. Liquids such as sweat can also cause problems such as dirt, corrosion and chemical weakening of materials.
It has long been recognized that exposure to atmospheric pollutants constitute a risk to museum collections. Outdoor pollutants produced by fossil fuels can damage paintings, textiles, and other works of art. Indoor pollutants generated by building materials can harm metal objects as well as other items.
Researches focused on outdoor pollutants including nitrogen oxides, ozone and other photochemical oxidants, sulphur dioxide, and particles and expanded to include indoor- generated pollutants specifically, formaldehyde, acetaldehyde, and formic and acetic acids. At the same time, the emphasis of research shifted from the macro-environment (Gallery and storage spaces) to the micro-environment (display cases and storage cabinets), where most of the damage from these indoor pollutants occurs.
Of increasing concern for collections in urban environments is the soiling of exposed surfaces, such as textiles, which cannot be cleaned safely or without difficulty. Internal combustion engines produce very small particles of nearly pure carbon, which cause extensive soiling.
Studies were carried out to determine the damage gaseous pollutants cause to various types of museums objects. Certain photochemical oxidant pollutants proved detrimental to a number of organic colorants. In addition, various materials were exposed to formaldehyde to measure their sensitivity to the pollutant. These studies confirmed that metals, and to a lesser degree shells, were susceptible to formaldehyde. Yet glass and ceramic glaze was not affected after 100 days of exposure. Recognizing the limited resources of many museums, researchers studied passive sampling devices that would allow museums to conduct their own surveys with minimal cost and expertise. Through testing, a number of commercially available, relatively low-cost products were identified that met the criteria for museum environments. This work has enabled many institutions to conduct economical pollutant surveys of their storage and display areas.
Also investigated were mitigation methodologies to reduce significant indoor concentrations of pollutants.
Those methods that proved effective used active filtration, passive protection, and combinations of procedures that worked along with the building’s ventilation system. The solutions are as simple as placing a tray of a sorbent material in a display case to absorb damaging pollutants or as thorough as identifying and isolating the offensive material from the display or storage space.
Pests
When we talk about pests, often thoughts turn to the common species that are known to transfer disease and infection, such as rodents, cockroaches and flies. However, not all pest species are what we might term as “public health” risks, and therefore the presence of some pests does not automatically mean there is an associated risk to people’s health. But, in the right environment, many pests can be incredibly destructive and will decimate their preferred food source.
In a museum or gallery, display or storage environment, the risk to exhibits or works of art from insect pests is a major priority. Clothes Moths and Carpet Beetles are the most common textile pests in the Museums, and an infestation of either or both can decimate a collection. They have the ability to digest the fibrous protein & “Keratin” which forms the main structure of natural materials such as hair or feathers and is present in leather. This ability and appetite put textiles and works made from wool, silk, fur, vellum and leather at risk. Damage caused by textile pests are performed by the larvae, making detection difficult due to their size, especially in the early stages of infestation. Early signs would be new holes in objects (Bringing into focus the importance of ongoing monitoring), and “Frass”. Frass is the excrement of the larvae, which might appear as a dust or powdery substance.
Pests in Museum Buildings Most modern buildings successfully prevent the entry of pests by careful design and detailing of potential entry points such as doors, windows and vents. Building standards and the improvements to heating and ventilation systems have also played a part in creating environments that are generally less attractive to insect pests. If you are planning a new building then it is worth discussing the special needs of your collection with the architect and including this in the initial design brief. In most cases it’s impossible to have a completely pest-free environment, Unfortunately, even with the most comprehensive controls, you still may fall foul of pests. It is not usually practical to totally exclude all pests from a building, so it is important that they are denied a suitable environment in which to feed and breed when they do get in.
Many insect pests can fly and may enter properties through open doors and windows. With moths and beetles, it is the larvae that cause all the damage. The longer you have adult insects in your property, the more eggs they lay and the more activity there will be to control.
So, act quickly if you see any insects, and inform your pest controller. The key to avoiding pest infestations is to understand the conditions under which they thrive. By denying them the four things they need-food, warmth, humidity and harbourages. It is possible to prevent them from becoming established if these four key factors are disrupted. The four factors are often inter-linked and achieving the right balance is not always straightforward, but it is also important you develop the right procedures.
Treatments
The choice of treatment method will depend upon the severity of the infestation, the type of material and the value of the object. The treatment of objects should only be carried out after taking the advice of a conservation or collections care specialist. In many situations, the application of an appropriate residual insecticide such as permethrin micro-emulsion will be sufficient to tackle an isolated outbreak of insect infestation. If your museum collection is made up of fragile and precious items, the pest control industry can offer you a number of innovative solutions to solve your textile pest issues.
Some standard insecticide formulations may not be suitable for treating specialist items. However, heat, cold, carbon dioxide and even hormone confusion can all be used as controlling agents for textile pests, so ensure your contractor is considering such processes to preserve the integrity of your collections. These developments in the pest control industry mean that museums now have a number of options for treatments that will prevent or eradicate pests, if carried out correctly. (Concluded).
