Lighting exhibitions for preventative conservation

One of the most frequent comments from visitors most galleries receive is 'You should turn the lights up'. It is often quite frustrating for visitors to come and view works of art on display only to find that it can sometimes be difficult to see them with the executed lighting. Why is everything so dark? The colours are not being shown to their full advantage. My selfie looks like a vampire!

Unfortunately for artwork, the tool that enables the work to be seen is also one of the most effective tools for making it disappear forever. Temperature, humidity, pollution, physical intervention, pest damage and lighting are all factors that need to be considered when caring for and displaying objects, but lighting is the one that seems to cause the most controversy.

Why does light affect objects? 

Light is a complex thing to explain. There are three main wavelength groups on the lighting spectrum that allows the human eye to see colour; Ultra Violet Light (UV), Visible Light and Infra-Red Radiation (IR).

UV and IR are invisible to the naked eye, but this does not mean they are harmless. Have you ever been sunburnt? That is UV working its painful magic! IR is mostly detectable to humans as heat.

Nearly all types of light contain all three components, but the amount of each component can vary: daylight contains a high level of ultraviolet radiation, tungsten light contains low amounts of UV but emits a high level of IR, LED lights also contain low to high levels of UV light, depending on the type of light used (Scottish Museums Council Fact Sheet – adapted for use in Australia 2003).

Many materials are particularly sensitive to light: paper, fabric, leather, photographs, and media (inks, colorants, dyes, and many other materials used to create objects and art). Aside from fading, there may be damage to the physical and chemical structure of materials. Visible light and UV provides energy to fuel the chemical reactions that lead to deterioration and while UV is blamed for most of this damage, visible light is also problematic. 

Intense lighting and long exposure times can lead to fading or changing colours in dyes and colourants. Ultraviolet radiation will lead to weakening, bleaching, and yellowing of paper and other organic materials. All of these changes can diminish readability, affect the aesthetic appreciation of artwork, and impact access to the information contained within the artwork. Even if you take a faded photograph down and store it in the dark, it will not return to its original appearance and will continue to fade when taken out again - unless we are talking about Cyanotypes, but that is another discussion.

Protection of objects

Because this damage is cumulative and irreversible, it is critical to understand how to protect materials in the first place, prior to displaying them. This is the foundation of thinking and planning for all preventative conservation.

It is sometimes thought that by eliminating high levels of UV light - by using LED lights for example - the risk for increasing the light levels is eliminated. Unfortunately, this is not the case as visible light causes destruction as well. Over time, there has been much research developed by scientists, conservators and institutions worldwide in order to create standards and practices to protect and preserve artworks while on display and in storage. 

Most collection materials can be on exhibit for three to four months at 50 to 150 lux and show no immediate fading. A level of 50 lux is similar to the low lighting in the evening in a regular home living room. For comparison, general office lighting is around 400 lux and direct sunlight measures 30,000 lux (D.Conn, 2012, Protection for Light Damage, NEDDCC).

Lighting is a complicated balance for exhibitions because if the light levels are to be higher than 50-150 lux, the length of time on exhibit needs to be decreased accordingly. When making the decision about exposure time on exhibit and light levels, low light levels for extended periods of time cause as much damage as high light levels for short periods. 

It is understandable for visitors to want to see the artworks in the best possible light (physically speaking) however it is important for them to understand that caring for the collection extends beyond displaying it in a beautifully, brightly lit way. For objects to survive for as long as possible, preventative conservation methods must be considered. Often one of the most impactful feelings when revisiting a gallery is observing a work you saw many years ago and the connection you had at that time. If we don’t turn down the lights to accommodate protective measures for the materials, your favourite artwork may not be visible, in any light, in the future.