As one of the Ten Agents of Deterioration, light damage initiates cumulative and irreversible material degradation making it a significant consideration in the protection of heritage objects and collections. Reducing light exposure is the most commonly used method of prevention as given by lighting guidelines and standards utilised within preservation environments.
Applying rigid schemas for display can however be problematic for equitable access and inefficient use of museum resources in frequent rotation of displays.
Lighting levels of objects on display impact visitor experience including safety and viewing comfort in addition to the rates at which the objects undergo colour fade and other detrimental consequences of photodegradation. Finding balanced and sustainable approaches relies on management practices that promote shared responsibility and consider the value of access and use of heritage to current audiences as well as those in the future.
The sensitivities of individual objects to light vary depending on factors that include previous exposure to light, substrate interaction, particle size, and colourant concentration (Tse 2019, p. 337).
Additionally the composite nature of many heritage objects benefit from a more tailored approach to protection from light rather than generalised categorisation of materials.
Tse promotes microfade testing (MFT) to determine the lightfastness of a given material in order to more accurately assess sensitivities to light. Customising lighting plans for collections with known light sensitivities can therefore provide a better foundation from which to calculate acceptable exposure times.
Practical methods of reducing UV radiation are applying UV filters to windows where objects are exposed to natural light and placing UV filters on artificial lighting sources. It is also prudent to monitor lux and UV levels with light/UV meters regularly.
As photochemical degradation is aggravated by high temperatures, relative humidity and oxygen, placing objects in micro-climates within anoxic environments may provide an alternate option for sustainably safeguarding heritage materials. (AK October 2021)
References and recommended reading
Ashley-Smith, J, Derbyshire, A & Pretzel, B 2002, ‘The continuing development of a practical lighting policy for works of art on paper and other object types at the Victoria and Albert Museum’, in R Vontobel (ed), ICOM-CC 13th Triennial Meeting, Rio De Janeiro, 22–27 September 2002, James & James, pp. 3–8.
Brokerhof, A, Kuiper, P & Scholten, S 2018, ‘Spread or Sacrifice: Dilemma for Lighting Policies’, Studies in Conservation, vol. 63, no. sup.1, pp. 28–34.
Cuttle, C 2007, ‘Light-induced damage to object’, in Light for Art’s Sake: Lighting for Artworks and Museum Displays, Butterworth-Heinemann, Oxford, pp. 39–49.
Ford, B & Smith, N 2011, ‘Lighting guidelines and the lightfastness of Australian indigenous objects at the National Museum of Australia’, in J Bridgland (ed), ICOM Committee for Conservation, 16th Triennial Conference, Lisbon, 19-23 September 2011, James & James, pp. 1–13.
Ford, B 2011, ‘Non-destructive microfade testing at the National Museum of Australia’, AICCM Bulletin, vol. 32, no. 1, pp. 54–64.
Ford, B & Smith, N 2011, ‘The development of a significance-based lighting framework at the National Museum of Australia’, AICCM Bulletin, vol. 32, no. 1, pp. 80–86
Saunders, D & Kirby, J 1996, ‘Light Induced Damage: Investigating the Reciprocity Principle’, in ICOM-CC, 11th Triennial Meeting, Edinburgh, Scotland, September 1-6, 1996, James & James, pp. 87–90.
Tse, Season 2019, ‘Microfade Testing for Heritage Institutions: A Canadian Experience’, Studies in Conservation, vol 64, no.6, pp. 337-351.
Vincent L. Beltran, JD & Maekawa, S 2012, ‘Large-scale assessment of light-induced color change in air and anoxic environments’, Studies in Conservation, vol. 57, pp. 42–57.
Bruce Ford 2013, ‘Breaking the rules: light-exposure risk assessment and micro fading’, Cultural heritage conservation science and sustainable development: Experience, research, innovation. International conference in the frame of the 50th anniversary of the Centre de recherche sur la conservation des collections – CRCC, Paris, 23 May, Published on 6 December 2013, viewed 10 September 2009. www.youtube.com/watch?v=c59HGiHE9SQ