What more stunning location could we ask for to view the sumptuous works of Raphael than the 18th century Scuderie del Quirinale in Rome?
The Raphael exhibition, which marks the 500th anniversary of the death of the great Renaissance master, runs from 5th March to 2nd June 2020 and features 200 masterpieces, making it one of the largest known collections of the maestro’s works .
Loaned items include “Madonna del Granduca” (1505) from the Uffizi in Florence, “Alba Madonna” (1510) from the National Gallery of Art in Washington DC, the “Madonna of the Rose” (1518) from the Museo del Prado in Madrid and the “Self Portrait with Friend” (1520) from The Louvre.
One practical consideration which comes into play with works loaned between museums is the variety of different requirements from the loaning institution for the conservation conditions under which the works may be exhibited.
Loaning institutions often place strict requirements on the thickness of the glass in display vitrines (for security reasons), air exchange rates inside the vitrine (for conservation), and the ambient light levels to which the works will be exposed (to reduce damage from light exposure).
At ArtRatio we have direct experience of this, since many of the collections we have had the honour of displaying include items which could otherwise not be exhibited due to their light sensitivity. Many come from private collections and are accompanied by strict requirements on light exposure, and limits on maximum fluctuations in relative humidity and temperature.
Examples of works we have housed include 15th century Books of Hours at the Swedish Nationalmuseum, original books by Sir Isaac Newton for a private collector in London and the original map of the 1815 Battle of Waterloo for the Royal Engineers Museum in the UK .
As one specific example, the Waterloo Map is very light sensitive and still has the original pencil markings of the 1st Duke of Wellington on it. Since graphite is a ‘friable’ medium, it can easily be ‘lifted off’ by nearby electrostatic fields. Hence on this project we had to take extra measures to control the relative humidity to reduce the build-up of electrostatic charge on nearby insulative materials (e.g. the glass) as well as earthing all metallic surfaces to reduce the risk of electrostatic charge from museum staff when opening the vitrine.
A Step Back in Time
The Scuderie del Quirinale (‘Papal Stables’) was built between 1722 and 1732 and offers a 180° view from the highest of Rome’s Seven Hills. With the desire to turn the building into a museum, significant restoration was required and the renovated museum was subsequently inaugurated in December 1999.
The magnificent hilltop views will come at a cost inevitably due to the high light levels that collections will typically be exposed to at that altitude. If you are thinking that it should not be a problem since all the artworks are inside the building, think again.
Moreover, UV levels increase with height, with 10% to 12% more UV for every 1000 metres increase in altitude . Since Quirinal Hill, where the Scuderie del Quirinale is located, stands at a height of 61m, we can expect to see just 0.7% more UV than at sea level, but when this extra radiation is accumulated over time, it can damage fragile artworks, like works on paper and textiles.
Light Damage on Art
Most clients we work with are acutely aware of the damage done by ultraviolet, but some are still surprised at the damage done by other parts of the electromagnetic spectrum (such as visible and infrared), and how even low light levels can inflict damage over longer periods of time.
To justify our claims, we turn to the CIE Technical Report 157 entitled “Control of Damage to Museum Objects By Optical Radiation”  which is summarised in Table-1 below.
We see from Table-1 that the most sensitive types of materials (CIE category 4) include silk, fugitive colourants and newspapers, which should not receive more than 50 Lux illuminance and definitely not more than 15,000 Lux-Hours light exposure per year.
Examples of fugitive colourants include indigo, lake, and gamboge, thus covering potentially painted objects based on materials not that sensitive to light, such as stone sculptures, wooden decorative art and glass.
Even under these strict display conditions, and even with UV-filtered light, you would still see a ‘noticeable deterioration’ on CIE-4 objects within 2 to 21 years. This is obviously not optimum for the long-term conservation of art collections.
Art is normally insured against transit, theft, fire and flood but not against ‘gradual damage’ from environmental conditions, since insurers cannot determine when the damage first started .
Extreme or fluctuating levels of light, humidity, temperature or air pollution can cause substantial long-term damage to collections, both superficially (as colour fading) and structurally (as breakdown of the chemical bonds in the artwork).
These environmental changes can deteriorate the condition (and thus the market value) of the collection, but the risk of gradual damage is not currently insured. So what to do about it?
Of the four risk response strategies mandated by organisations such as the Project Management Institute (PMI), if we cannot transfer the threat (e.g. insurance) nor avoid the risk (by not exhibiting the collection), the only option left is to mitigate the risk, which involves taking precautionary measures to reduce the damage. So, what are these measures? Let’s have a look.
Solutions to Manage Light on Art Collections
Art collections, whether public or private, are currently protected from light by various solutions, such as window blinds and curtains, timer-controlled lighting, replacing fluorescent lighting with LEDs, object rotation schemes and UV filters on windows and on light fittings.
All these measures however assume that the objects within a collection have the exact same sensitivity profile, which is not always correct, as pointed out by the British Standards Institute Document BSI PAS 198 :-
“Museums need to shift guidance given to architects to the conservation needs of different categories of objects, which have widely different requirements.”
UK National Museum Directors’ Conference (2009)
It would be nice from a museum curator’s viewpoint to be able to place sensitive and non-sensitive objects next to each other if they portray a particular story, without having to place all objects at the lowest light level suitable only for the most sensitive items.
For this reason, ArtRatio has created a solution made from smart (electronically-switchable) glass, that can ‘switch off the lights’ on objects, for example whenever no-one is nearby to view them, or when the light exposure suffered by the object is nearing its annual ‘quota’, as recommended by standards bodies such as the CIE.
Housing certain objects in darkened glass vitrines seems like ‘tough medicine’, but our objective has always been to find that elusive balance between exhibition and conservation, through the smart and sustainable display of art collections.
“Largest ever number of Raphaels gathered for ‘mega-exhibition’ in Rome”, The Art Newspaper, 4th March 2020.
“Ultraviolet Radiation and Health”, World Health Organisation.
“Control of Damage to Museum Objects By Optical Radiation”, Technical Report 157:2004, International Commission on Illumination, ISBN: 978-3-901906-27-5
“Fine Art and High Finance”, Dr. Claire McAndrew, ISBN: 978-1576603338
International Ultraviolet Association.
British Standards BSI PAS 198:2012 (superseded by BS EN 16893:2018 and BS 4971:2017).