12 minute read
The Art of Illumination
In a thought-provoking dialogue, designing lighting global editor Ray Molony talks to lighting and conservation expert David Saunders about striking the right balance in lighting design for invaluable art pieces.
By Ray Molony
You famously once said that ‘the objects in the British Museum won't last forever’. Was that remark just another way of restating this philosophy?
It was a controversial thing to say, but I said it because I wanted to make a point.
It’s not just light that does the damage. For many objects, light is not the key agent in their deterioration.
It might be moisture. It might be pests. It may simply be that if they're stored at room temperature for any length of time, they’re going to deteriorate.
Plastics are a very good example. We know that light deteriorates plastics.
But putting them in the dark is no guarantee that they won’t deteriorate.
I’d qualify that comment by saying that it might be millions of years before some of those objects finally turn to dust. But they will.
So we have a responsibility to think about that lifetime.
We have to think how what we do might accelerate that loss. How do we apportion out that loss so that we split the enjoyment and appreciation of objects across generations.
In my book, I emphasise that we have to know our collection. We have to know its vulnerabilities. We have to know our audience because that is also going to tell us how much light is needed to appreciate it. But perhaps the toughest thing is that we need to know our own mind.
We have to make a decision about how long we want or expect a collection to last because without that, you can't join the future and the present together. You can't make that balance if you don't have a view as to where the risks lie.
A few research groups have made digital copies of objects and added a degree of change, such as fading, and they go to a panel of people and say: ‘Here's the object as it is now, and here's what it might look like in the future after some change has occurred. Over what period of time would you feel comfortable with that change occurring?’
That's the way that it tends to be done. Most of the discussions come down to a 50-year region where people are comfortable. They expect to pass it to the next generation and maybe the generation after that.
Would you take a different approach for the iconic works?
Well a number of paintings by Van Gogh were actually part of the studies. There are some pretty sensitive pigments in them. There's a pigment called eosin, known also by its commercial name of Geranium Lake, which was used a lot by Van Gogh, which is so fugitive that most of it's gone by now. When the Van Gogh Museum did this study they actually changed their lighting policy as a result of it because they realised that they weren't going to meet those expectations.
So for every object, you're making a decision – whether consciously or not – to strike a balance between illuminating it for a visitor and preserving it for future generations?
You are. But a way of thinking about it that doesn't make it such a dichotomy is to think of it as either illuminating it for the visitor now, or having it for the visitor in the future. It's visitor enjoyment and appreciation now versus visitor enjoyment and appreciation in the future.
That's quite an awesome responsibility for a curator to make that call.
It absolutely is. But it allows the curator, for example, to say, ‘Well, I'm not going to display this object at a low light level where no one can see it because that benefits no one. We’re taking away some of its lifetime for no benefit because no one can see it and appreciate it’.
Can you recall a specific example where that discussion went on?
I recall a decision by the Getty with some handcoloured daguerreotypes where they put them in display cases which were only illuminated when the visitor kept their finger on the button.
Many galleries these days opt for general wall washing and it’s seen as very practical approach as you can move artworks around. Is it a cop out in your opinion?
It’s not new. You can trace back the idea of trying to wash a wall with light in a very even way to the interwar period at least.
That was when a lot of the big American museums built these gallery spaces, which had laylights and lights in the roof space so the light in the room was extremely diffuse.
Wall washing democratises things as it gives equal weight to all objects. Large paintings often look quite good in this type of light because it doesn't produce a huge amount of glare.
Other things look terrible. With works with low relief, you just lose all sense of it. So for anything with three dimensionality, wall washing can sell you short.
At the other end of the extreme, spotlighting or framing something can produce a very strange impression. I've seen framing spotlights used in a way that makes two dimensional works of art look like they're back lit.
Maybe we're so used to seeing backlit things like computers, that there’s a kind of receptivity to it now, but it does produce a very strange result.
There will always be objects that the public and the curator consider more important, which they might want to highlight. If the lighting could draw visitors to the key objects in the room, then maybe that is a good thing for people whose time is short or whose background knowledge is not great.
So in your view highlighting is a key component?
I believe the right approach is to provide a base wash of light so that an object is visible, and then you add directional light to show the three dimensionality.
Two dimensional objects definitely look better if there's a degree of accent lighting because they can look very flat in flat light.
But it’s important to use a relatively even light over them because you don't want the centre of a large object to be very bright compared to the periphery.
And remember too that sometimes the most interesting or the most telling features of an object or artwork are not always at the centre.
The Dulwich Gallery in London recently engaged Star Wars cinematographer Peter Suschitzky to dramatically illuminate works by Rembrandt to emphasise the painter’s relationship with light. Are you a fan of this type of innovation?
Unfortunately, I didn't get to see the show but I don't regard the use of light in this way as a kind of heresy or anything like that. I think it needs to be thought about carefully and I think you need to explain what you're doing and why you're doing it so that people understand that they’re seeing the paintings in a rather different way.
There was an example at Kelvingrove [Art Gallery and Museum, Glasgow, Scotland] of a painting where lights illuminated certain parts of it to guide you through what was happening in the composition. After a period, the painting was then lit normally so you could see it as a whole object. I think this is good as it’s educating people about the object and the thoughts going through the artist’s head.
In the case [of Dulwich Gallery], I think it was really justified because it was talking about how light was used in Rembrandt's work.
Another example is [Mark] Rothko’s series of paintings for the Harvard Art Museum, which they lit with a structured light that attempted to recreate the colour before fading. Using very scientific principles, they projected coloured light onto the object which compensated for the colour loss. So it looked as it might have appeared when it came out of Rothko’s studio.
They would turn the light off periodically so you could see it in its current state and there was a lot of signage around so that visitors were aware of what had been done.
It has been done with tapestries as well, by projecting light with the colour that's faded away.
These approaches are all fine providing they’re not done to deceive.
Do curators have any responsibility to the original intentions of the artist? If a painting was originally intended to be seen in certain setting, are we being inauthentic if we display it differently?
One of the examples that's often given is pieces that were intended to be seen in churches and they'd often be in side chapels in candlelight. And they would be seen quite poorly, frankly.
We could recreate that poor lighting and sometimes we do, as an experiment or a demonstration of how they might be seen. And you can gain something from that as well. If it’s candlelight, you get a certain atmosphere, but actually it’s a very poor way of seeing an object. So I think we would lose more than gain by doing this.
However, if there was good documentary evidence that, say, an object was lit from the left in its original setting, then we could go along this route, but occasions when you have evidence like this is relatively rare.
If we were to take authenticity further, we would end up putting everything in daylight or in some warm, artificial electric light because most things were created in either daylight or in candle, flame or possibly gas, until you get to the very late nineteenth century.
Do you think curators are well served by current lighting metrics such as the colour rendering index? After all, under incandescent light, it’s possible to confuse dark blue and black, for instance.
The colour rendering calculations are a bit weighted towards certain types of lighting. Daylight and incandescent sources are theoretically perfect so what you're seeing there is not a colour rendering issue, but potentially something called matamarism, where colours don't look the same under different lights because of the way they behave in different parts of the spectrum.
This has always been the enemy of the restorer. There was an example of a Canaletto painting at the National Gallery [in London] that was very painstakingly retouched in daylight in the studio. When it was taken into the galleries – which at that time were lit with fluorescent lights – all the repairs in the sky appeared pink!
So the painting spent just a month on the wall and then went back to the studio again where it had to be redone.
The problem arose partly because of the difference between daylight and fluorescent light – with its spiky spectrum – and partly because the pigment that had been used in the original sky was something called Prussian Blue.
And it had been retouched with the ‘wrong’ blue. This blue had a ‘kick’ at the red end, which you didn’t notice when it was in daylight but you noticed it when it went into the gallery.
Has the adoption of LEDs reduced these colour issues?
They haven't gone away. I think that LEDs have rather better colour properties than fluorescent. Some fluorescents were pretty spiky, particularly the higher efficacy triphosphor lamps.
It’s better now with LEDs, and restorers are now taught about matamarism more thoroughly and are a bit more careful about the pigments they use.
Do you believe we’re changing our cultural taste for colour temperatures because of digital screens?
There’s a preference for warmer light in an interior setting at lower levels and cooler light in an external setting. I'm sure that's built into our cultural and evolutionary history.
But if you look at some of the experiments that give people a choice of different colour temperatures of light there does seem to be a shift towards higher colour temperatures. In some cases, there are quite extreme shifts up into the 5000K region.
At the National Gallery, colleagues showed 8,000 visitors objects lit with four different colour temperatures. I think one was candlelight, one was incandescent, one a 4000K source and finally a daylight source.
It was quite a robust study, although it’s still unpublished. They switched around the order the visitors saw them in etcetera, so they were able to take out a lot of statistical noise.
Remember too that the visitors had just come out of a gallery that was probably lit in the 3000K range.
I don't have the exact figure, but 70 to 80 per cent of the visitors went for one of the two cooler sources as their preference.
- This interview with David Saunders first appeared in Erco Lichtbericht magazine
DAVID SAUNDERS: BIOGRAPHY
David Saunders is an honorary research fellow at the British Museum, having been keeper of conservation and scientific research there for ten years, until 2015. He was previously in the Scientific Department at the National Gallery in London. He is a fellow of the Society of Antiquaries of London and vice president of the International Institute of Conservation. In 2015-16, he was a guest scholar at the Getty Conservation Institute, conducting the research that underpins much of his book, Museum Lighting: A Guide for Conservators and Curators (Getty Publications/Yale).
