1. An early warning system for light damage in museums and exhibitions M. Bacci a, C. Cucci a, S. Gerlach b, H. Roemich b, A.-L. Dupont c, B. Lavedrine c and G. Martin d a Istituto di Fisica Applicata "Nello Carrara"-(IFAC), Via Panciatichi, 64, I - 50127 Firenze b Fraunhofer- Institut für Silicatforschung, Bronnbach Branch, D – 97877 Wertheim c CNRS / CRCDG, 36, rue Geoffroy-Saint-Hilaire, F - 75005 Paris d Victoria & Albert Museum, South Kensington, SW7 2RL London 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

2. Interaction between light and the art object To be appreciated by the observer, the object needs to be illuminated, even if light can cause irreversible damage to the colours Light is energy To illuminate an object means to supply it with energy A compromise has to be reached so as to allow a satisfactory reading of the painting while keeping the lighting at sufficiently low levels

3. LIGHT TEMPERATURE RH POLLUTANTS COOPERATIVE EFFECTS? Lighting is not the only cause of colour fading. The presence of pollutants and unsuitable temperature and humidity conditions can amplify and accelerate photo- alteration processes 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

4. THE EQUIVALENT LIGHT DOSE (ELD) Co-operative effects cannot be correctly evaluated by a separate measurement of each environmental parameter In order to give a semi-quantitative indication of the amount of the cumulative damage we have introduced the concept of ELD

5. 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004 DEFINITION OF “EQUIVALENT LIGHT DOSE” The ELD can be defined as the light-dose which is capable of producing, in a given material in an uncontrolled environment, the same spectral variation as that measured in the same material exposed under well-defined and controlled environmental conditions

6. Accepted annual luminous exposure limits from published data (Tétrault,2003) Category Examples of artefacts After 100 years, a just noticeable fading will result from a maximum luminous exposure of High sensitivity ISO 1,,3 Graphic documents, albumen prints, colour photographs, parchment, leather, textiles, tapestry, natural history specimens 10 000 lux h per year Moderate sensitivity ISO 4,5,6 Oil paintings, tempera, wood, polychrome sculptures, bone, ivory 100 000 lux h per year Low sensitivity ISO 7,8, above Stone, metals, ceramics, B/W photographs 3 000 000 lux h per year 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

7. The global microenvironment can be much more dangerous to paintings than light alone After 9 months of natural exposure in different museums, some tempera sensors, which were prepared for this purpose (ERA project, Contract N. EV5V CT 94 0548), showed alterations even in a controlled environment: in some cases, this exposure corresponded to more than 50 years of exposure to lighting of 200 lux. 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

8. Installation of the IFAC-CNR prototype inside the “Geographic Maps” room at the Uffizi Gallery 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004 dosimeters reference Fibre optics Automatic recording of the dosimeter colour ELD is evaluated on the basis of a previous calibration, performed by means of an accelerated ageing test A photodiode measures the actual light

9. A test of equivalent-light dosimetry over 300 days 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004 Uffizi Gallery IFAC-CNR laboratory Travel to and exhibition at Valladolid, Spain

10. 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004 A simple measurement of the light dose could be not sufficient to assess a possible risk We have verified that in natural conditions the fading is always greater than the expected one on the basis of the light dose received Therefore

11. 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004 Need for a device, which, in some way, can integrate the effect of the different environmental factors A light dosimeter for monitoring cultural heritage: development, testing and transfer to market “LiDo” Project EC-contract EVK4-CT2000-00016

12. Fraunhofer-Institut für Silicatforschung (FhG/ISC), Germany Istituto di Fisica Applicata „Nello Carrara“ (IFAC), Italy Victoria & Albert Museum (V&A), United Kingdom National Inst. for the Preservation of Cultural Heritage (SUPP), Czech Republic Náprstek Museum (NM) and others, Czech Republik Dr. Dieter Kockott UV-Technik (DK) Germany Particle Technology (Par Tech), United Kingdom Centre de Recherches sur la Conservation des Documents Graphiques (CRCDG), France SUPP-CZ

13. data-logger recording VIS light, UV, T, RH LCU BWS1 - Evaluation of effects of the exposure in terms of the colour change (  E*) - Investigation on the relationship:  E*  Luminous Exposure (= I t) LCS “Maestà”, Giotto (c.1310)-Uffizi Gallery-Florence The basic idea : 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

14. The aim of the project: development and testing of light dosimeters and their transfer to the market Selection of dyes/matrices/substrates Laboratory experiments Field application Standardisation of the preparation method SUPP-CZ Exposure of light dosimeter in the V&A London next to sensitive carpet

15. To obtain a colour variation of  E  10-12 the exposure needed is 12 kluxh for LCU 60 kluxh for LCS 250 kluxh for BWS1 A comparative test: LightCheck ® U, LightChek ® S and BWS1 Calibrations curves Artificial light-ageing in light-chamber - (500 lux quartz halogen lamp at T=23 °C, 50 %RH) LCU LCS BWS1 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

16. Low exposure levels are detectable with LightCheck ® Different degrees of light-sensitivity are found light-sensitivity BWS - LCS - LCU BWS - LCS - LCU LightCheck ® U and LightCheck ® S have different and complementary operative ranges: LCU up to 100 kluxh LCS from 90 to 400 kluxh 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

17. LCULight Dose (Klux.h) 4U75 - 100 3U45 - 75 2U30 - 45 1U5 - 30 0U0 - 5 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004

18. LCSLCU LCS and LCU work in a fashion analogous to that of a pH indicator

19. 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004 LIGHT DOSIMETERS LTD 32 CAMDEN LOCK PLACE, LONDON NW1 8AL, U. K. TEL + 44 207 267 7555, FAX + 44 207 267 1555 UK VAT REG NO. 828 5021 35 e-mail: david@outlookres.co.ukdavid@outlookres.co.uk All North American enquiries should be to www.keepsafe.cawww.keepsafe.ca All French speaking enquiries should be to www.atlantis-france.comwww.atlantis-france.com All German speaking enquiries should be to www.cwaller.dewww.cwaller.de All other enquiries should be to david@outlookres.co.ukdavid@outlookres.co.uk LCU and LCS started being sold in June 2004. First clients include the National Library of Czech Republic; the National Library of Ireland; the Tate Museum, London; the Getty Museum, California; the Smithsonian, Washington D.C. ; the Victoria and Albert Museum, London; the National Museum of Sweden; the National Trust, Britain

20. 6 th Indoor Air Quality 2004 Meeting – Padova – 10-12 November 2004 ACKNOWLEDGEMENTS This work was supported by the EC Project ‘LiDo’: A light dosimeter for monitoring cultural heritage: development, testing and transfer to market (EVK4-CT-2000-00016), under the Fifth Framework Program. Thanks are expressed to Dr. Anna Maria Petrioli and Dr. Antonio Natali (Soprintendenza “Polo Museale fiorentino”), who allowed the authors to place the dosimeters in the Uffizi Gallery.