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| Shedding light on cultural heritage

Objects of importance to Europe’s cultural heritage – such as old photographs, documents and tapestries – need careful looking after, while remaining accessible to scholars and the public. Museums and galleries must monitor and assess the exposure conditions these delicate artefacts face when being exhibited, otherwise they could fade and suffer irreparable damage. The European Commission-funded LiDo project has devised an easy-to-use product for conservators and other cultural heritage professionals that can show them the environmental impact of light on an object over a period of time.
A technician with LightCheck and calibration chart (photograph: Fraunhofer ISC, Wertheim).
A technician with LightCheck and calibration chart (photograph: Fraunhofer ISC, Wertheim).
Anyone visiting a museum or an historic archive will probably be struck by the different levels of lighting that are used in different rooms for different exhibits. Some objects may be quite brightly lit while others may only be seen in darker surroundings, such is their frailty. Those responsible for looking after Europe’s cultural heritage know that light is the ‘enemy’ – too bright or too long an exposure can ruin priceless objects forever.

Some conservators and curators have used the British Wool Standard (BWS) to measure light conditions. Unfortunately, this technique is designed for industrial use and is not really sensitive or accurate enough to be applied to precious artefacts.

Consequently, a new approach was required to measure light exposure so that display conditions could, when necessary, be adjusted to allow for viewing while minimising the risk to important assets. This is where the LiDo – or Light Dosimeter – project stepped in. LiDo answers the call for a more sensitive and standardised technique that is easy to handle, environmentally robust and inexpensive.

The research work started in February 2001 and was completed January 2004. The team had to be interdisciplinary in nature, bringing together scientists, manufacturers and conservators, all of whom made their own specialist contribution to the project.  Members included: the Victoria and Albert Museum in London; the State Institute for the Care of Historical Monuments, a local authority based in Prague; and industrial companies Kockott UV-Technik from Germany, and Particle Technology from the UK. Research institutes taking part were the Paris-based Centre de Recherches sur la Conservation des Documents Graphiques, the Istituto di Fisica Applicata from Florence, and the Fraunhofer-Institut für Silicatforschung, acting as project coordinator.

All change

Laboratory tests centred on creating a photo-sensitive coating that could be applied to a paper or glass substrate, which would change colour during exposure to light. The project scientists then established a precise calibration between the colour change and exposure levels. The exposure and corresponding colour reference can give the end-user valuable information about how much light an object is absorbing.

Field trials were carried out on the new dosimeter in museums in London, Prague, Florence, Berlin and Paris. The aim was to provide clear and precise calibration charts to evaluate colour change on-site. Researchers looked at issues such as light levels in summer and winter, different exposure times, the influence of different light sources, and how fading comes about over time. These tests were vital as LiDo’s work encountered real-life variables such as different humidity and climatic conditions, variations in UV protection, and differing levels of artificial and natural lighting.

Raising standards

A LightCheck strip placed next to carpet (photograph: V&A, London).
A LightCheck strip placed next to carpet (photograph: V&A, London).
The work proved to be a great success. The new light dosimeter comes in strips (approximately 7.5cm x 2.5cm) that can be placed next to objects – two commercial, registered products have already been developed, both of which are more sensitive than BWS. LightCheck Ultra is capable of monitoring very light-sensitive objects during short exposure times, while LightCheck Sensitive can be used with more durable artefacts that can withstand longer exposure.

The LightCheck products act as early-warning systems for preventative conservation, since they indicate risks long before any damage is done to the object. Conservators and gallery owners are provided with the light-sensitive strips and a colour chart so that they can evaluate the quantity of light – and the potential damage – their precious objects are subjected to during an exhibition. Using the information LightCheck provides, they can adjust exposure times and change conditions as they see fit. Because the appliance is so portable, it can also offer vital information on light levels and exposure times when objects are loaned to other museums.

Only half a day of training is needed to learn how to use the dosimeters, and this is backed up by technical support on the official LiDo website. According to the project coordinator, the product’s ease of use is likely to help art historians, curators and decision-makers understand the concerns more technically qualified conservators may have about exposing objects to too much light or placing them in the wrong environment.

LightCheck is already proving to be a great success. The project was awarded the Pan-European Grand Prix for Innovation in Monaco in December 2003. Now marketing of LightCheck is moving forward at a pace, backed by thorough market research. The project surveyed more than 100 museums and galleries to gauge interest in light dosimeters. More than 90% of them said they were concerned about the effect of light on their exhibits, and showed an interest in an accurate, low-cost product that could warn them about potential light-induced deterioration.

Indeed, the market potential for LightCheck products is vast – Europe alone has between 15 000 and 20 000 museums and galleries, not to mention hundreds of private houses and estates that are stocked with precious and delicate artefacts needing protection. LightCheck Ultra is already on the market and can be ordered on the internet, while final practicalities are being completed on LightCheck Sensitive. As of November 2004, around 300 had been sold in Europe.

Practical uses

As part of the marketing push, a number of seminars and events have been held around Europe to explain the work of LiDo to professional audiences. For example, the new dosimeters were shown to an international audience of 30 conservators in Malta. A practical demonstration illustrated how LightCheck works and the project team was able to get valuable feedback which will help refine the product. Schools which train conservators have been targeted to explain the tool’s value. The hope is that tomorrow’s guardians of Europe’s treasurers will come to use the new dosimeters on a regular basis.

The technology developed by the project could also have uses outside cultural heritage. A dosimeter has been developed for health and safety use to monitor people’s exposure to light in the work place – the ‘ergo-light watch’ has already been patented.


Project information

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