Talk given at a joint meeting of ICOM-CC, the conservation committee of the International Council of Museums and ICEE, the International Committee for Exhibition Exchange, in a session called "Exhibition or Destruction", ICOM general meeting. Stavanger, Norway, July 5 1995. Unpublished.
Before I begin, I would like to ask you all two questions.
First, how many of you came to Norway by aeroplane? Hands up!
Well, before you take your return flight, I think you should know that the most dangerous parts of your trip are take-off and landing. And, for each of these flight events, there is a risk of around one point three fatalities in every one million. A risk of death of one in 325,000 for a return flight.
My second question is, How many of you have ever bought a lottery ticket? Hands up!
And a supplementary question. How many of you have ever won the big prize, the jackpot?
I would estimate, as a scientist, that that was about the same number of you, here today, that has ever been killed from travelling in an aeroplane!
But just think back. When you made that booking, for the flight to this conference, you knew there was a risk. You knew that, not only was there a small but real chance of total annihilation, but that there was a 100% chance of being damaged by jet lag, by airline food and by complementary beverages.
But you compared these risks with the benefit of coming to this conference. The midnight sun, the beauty of the fjords, and something to do with museums. And you weren't being selfish in this analysis. You knew that large numbers of your international colleagues would benefit from your wit and your wisdom. And your colleagues at home would benefit from your report and your gossip.
You compared these benefits with the potential losses. Suppose, at the point of leaving Stavanger, you were to contribute to that figure of one point three fatalities. What would be lost? All those learned papers that you are going to write one day, once the pressure of administration subsides. All that accumulated knowledge could be lost without a trace. Yet you assessed that the short-term benefit of attending this conference far outweighed the risk of losing the long-term benefit of your unique expertise.
So, even before I begin my talk, you know exactly how to ...
[Slides 1 (L & R) "Consider the benefits" "Calculate the risks"]
I am told that in museums around the world there are just two sorts of people. Those that can see nothing but the benefits of temporary exhibitions and international loans and those that can see nothing but the risks of damage and decay. Each group is determined to spoil the fun of the other.
[Slides 2 Picture of two people, Brian and Linda Picture of two people, Sue and Leesa]
In a large museum, such as the V&A, with an active loans and exhibitions policy there are a large number of people involved in preparing exhibitions on site, and preparing objects for travel to exhibitions at other venues. Pictured here is a small fraction of this large number of people. From left to right : Administrator, designer, curator, conservator.
They all have different areas of expertise and different areas of responsibility. They all have different motivations and different ways of judging whether an exhibition is a success. Possibly, under the pressure of an exhibition deadline, they might occasionally forget that any view but their own should be considered. But the important thing is that they are all smiling.
[Slides 3 Picture of Director (looking grim) Picture of Chairman of Trustees (trying to smile?)]
Its obviously a little more difficult to smile if you are director of a national museum or the chairman of its board of trustees. This is because you are more directly concerned with the financial consequences of success or failure. You are likely to be concerned with political and diplomatic benefits. You get upset when some smiling conservator says it is out of the question for that one politically key object to travel.
But if the right people are involved in decision-making for exhibitions, at an early stage. If each will respect the area of responsibility and expertise of the other. And, most important, if they truly deserve that respect. Then there is every reason to suppose that, from an organisational point of view, the exhibition will be a success. And everyone can smile.
First everyone in the team must understand the benefits.
[Slides 4 Benefits Money Enjoyment Outreach Marketing Scholarship Conservation]
On this last point, one thing that exhibition organisers should appreciate is that both curators and conservators worry that exhibitions and loans distort conservation priorities and that objects are treated for no other reason than to withstand the rigours of travel.
[Slides 5 Pictures of Japanese exhibitions with Japanese people... ...overwhelmed by beautyof V&A objects!]
However, the recent series of travelling exhibitions from the V&A to Japan exemplify these benefits. We pocketed a large exhibition fee, we fulfilled our museum mission statement by increasing enjoyment and understanding, we reached out to people of a different culture, we sold V&A merchandise and marketed the V&A brand name. Scholarly catalogues were produced, and more than a thousand objects were inspected of which, a substantial number were treated.
Now these benefits, which are not all readily measurable in monetary terms must be compared with the costs.
[Slides 6 Costs Examination Preparation Transport Packing Courier Monitor Damage]
All the costs, except possibly the last, Damage, are directly measurable as money. Money spent on staff time, materials or services bought.
The object must be examined to see that it is in a fit state to travel and to be exhibited. If it is not it will need some treatment or preparation.
It must be packed in a way that relates to its size, weight, complexity and fragility. In a way that accounts for its sensitivity to changes in temperature and humidity. Good packing is expensive to begin with but it also adds to the volume of the shipment which increases the costs of transport.
When exhibition organisers try to cut costs they often try to eliminate the courier. Undoubtedly there are times when the object's best interests would be served if someone did eliminate the courier. But when someone who understands the physical nature of the object and its relationship to the environment is selected as courier, then both the object and the exhibition can benefit.
It is wise to monitor the environment to which the object is going and relate this to the environment to which it has become accustomed. This incurs a cost in logging equipment and in time to analyse the data.
Lastly, there is a risk that some damage will occur.
All the costs on this list are those associated with the physical movement of the object. All of the processes mentioned require input of expert advice. The area where most of this practical expertise is developing is in conservation departments of major museums where there are scientific staff or in major national centres of conservation research. It would therefore be expected that an intelligent and communicative conservator or conservation scientist would be an essential member of an exhibition planning team.
[Slides 7 Pictures of damage to Minton vase Cracked snake handle]
Yet, Unfortunately, despite this increasing expertise damage will still sometimes occur.
The conservator will assess that an object is strong enough to travel. The packers will estimate the probable stresses of dismantling and reconstructing this complex object and devise a packing system that doesn't exert undue pressure on delicate parts . And yet damage occurs.
In retrospect we would say that such a heavy, complex, fragile object should not have been allowed to travel. If we are open about our failures it will help others make better judgements in the future.
Now, If we consider the benefits of an exhibition and compare them with the costs, we are doing a cost-benefit analysis. In Museums it is rare for this to be a very formal exercise. Usually the director or a senior curator makes a quick subconscious assessment. The benefits, which are difficult to quantify but easy to justify, can readily be made to outweigh the costs, which will be charged to the borrower anyway.
But if, as part of the planning of an exhibition, you did carry out a formal assessment, you would find that although you were able to put an exact price on all the time spent, on all the materials, services and equipment to be bought, you couldn't put a price on the damage. Because it hasn't occurred yet. This is where the study of risk becomes useful.
There are some kinds of damage that may or may not occur. There are some kinds of damage are inevitable but you don't know to what extent they will occur. It depends on the object and on which hazards are being considered.
[Slides 8 Hazard Earthquake Plane crash Road crash Vibration Case drop Object drop Installation Dust Light Air pollution Case pollution Humidity extreme Temperature extreme Humidity variation Temperature variation Fire Theft]
There are so many hazards, from earthquake to air pollution, from the heat of a fire to extremes of humidity, that its a wonder that any objects survive. But this is a list of possible hazards. Things with a potential to do harm. They may not be present in some situations and, when present, they may not actually affect the objects.
Moreover when you consider sending an object from your own institution to another place, you should consider only the additional risks of the journey and the new location. The object is already at the mercy of most of these hazards even when supposedly safe at home.
[Slides 9 Left: On the Move Plane crash Road crash Vibration Temperature extreme Humidity extreme Case drop Object drop Installation Theft Right: Just Sitting Quietly Dust Light Air pollution Case pollution Humidity variation Temperature variation Humidity extreme Temperature extreme Earthquake Fire Theft]
Here I've divided that long list of hazards into two groups. Those that relate to objects sitting quietly doing nothing and those that relate to objects jet-setting about.
Look on the left hand screen at objects "on the move". I have highlighted in red where the risks from those hazards are appreciably greater for a loan to another institution than they are if you are installing a new display in your own museum.
Look at objects "just sitting quietly". Once again I have highlighted in red where the risk to the object is appreciably greater if it is sitting in someone else's museum or gallery rather than sitting in the gallery outside your office. (there is no red on the screen! )
Highlighted in pale green are the hazards that might, just possibly, in a worst case scenario, present a greater risk. Of these all but theft and earthquake are easily controllable at the design stage. Even the chance of theft and the effects of earthquake can be minimised by good design.
But as you glance down this list you say, "no, no!", surely the risks of vibration are much greater when the object is on the road rather than moving around in the Museum. Probably not.
Two years ago we measured levels of shock and vibration for the movement of paintings between Osaka and Tokyo in Japan.
[Slides 10 Pictures of Japanese warehouse lifts and lorries]
At Osaka the paintings were loaded onto trolleys and moved into the lift to the ground floor where they were loaded into air-ride vehicles. After a 10 hour journey they were unloaded and man-handled up nine flights of stairs.
[Slides 11 Picture of case going upstairs Chart (explained in text)]
In the lorry ( the central section of the graph) there is no measurable shock or vibration. While the paintings were entirely in the hands of the object handlers there was some slight shock. But while the object was being moved in what might be considered the most careful way, in a purpose built store, using trolleys and lifts, it suffered accelerative forces of up to 4 G. And although these are actually quite small for a robust object such as an oil painting the important point is that they are considerably greater than anything suffered during ten hours on the road. They equate to what is probably happening in your own museum.
I've been talking about risk but I haven't yet explained what I mean by that word.
[Slides 12 Left: Risk Random events Probability x Loss in Value Continuous exposure Time x Ratex Loss in Value Risk 0.0001 x 100% = 0.01% 1 x 0.01% = 0.01% 10000 hrs x 50 lux x 0.000002% = 0.01% 200 hrs x 250 lux x 0.000002% = 0.01%
For events that are more or less random, such as someone dropping a pot or an earthquake shaking it off a shelf, risk is defined as: the probability of that event multiplied by the loss in value resulting from that event. Value could be measured in dollars or in do-nuts. But for the duration of this talk I shall be using percentage change in value. This avoids the danger of offending anyone by giving a monetary value to objects that may be either priceless or worthless.
For hazards such as pollution or exposure to light, the degree of damage is likely to be directly related to the exposure. Risk can be defined as the extent of exposure multiplied by the loss in value for each unit of exposure.
Look at the first two examples on the right hand screen. These relate to random events. In the first there is a very small probability (one in ten thousand) that there will be total (100%) loss. In the second there is a probability of one (absolute certainty) of a very small loss in value (one hundredth of one percent). Both have the same magnitude of risk.
The lower two examples refer to continuous exposure to an agent of deterioration. In this case light. A short exposure to a bright light does the same amount of damage as a longer exposure to one that is less intense. The figure of 'point five noughts two %' is my own estimate of the loss of value to a sensitive work of art on paper caused by one lux hour of exposure.
By using such calculations it is possible to compare the risk of damage by light due different types of display. We can also then compare these with the risks of random events such as fire or theft.
Of course, it is not at all easy to come up with the figures that go into such calculations. Some are easier than others.
For events like plane crashes the total number of successful flights is recorded and all failures are well documented. But for events like the dropped museum object, the number of successful transfers is not recorded and the number of failures is suppressed. But within your own institution you can probably come up with a figure that is accurate to one power of ten and that may be all the accuracy you need. Needless to say the figure will be very, very small.
Changes of value are even more contentious, but I am told that a group of colleagues can be guided towards some sort of consensus. Again an accuracy of one power of ten is all that is needed.
[Slides 13 Risk chart (transit) Risk chart(sitting still) (explained in text)]
These two charts represent my rough, first pass, estimates of the relative risks posed by different hazards to a wide range of objects. Such as the V&A has recently sent out in large travelling exhibitions. (so rough and ready I am not yet prepared to air them on the net!!!) Again they are divided into the risks of moving about and the risks of sitting still. The longer the coloured bar, the greater the risk. The end of the orange section marks the worst possible case, the greatest probability combined with the maximum loss in value.
The end of the yellow bar represents something like an average risk. Theoretically there is no minimum risk but,in practice, there are diminishing returns in the effort needed to reduce the risk. More important the numbers become so small that they are really indistinguishable from zero.
This line here represents the point at which the numbers have become so small that they are negligible. On this scale the line is marked minus 6, which means a risk of 'ten to the power minus six' percent, that is one millionth of a percent.
At the other end there is a line at +2, a risk of ten to the power of 2 or one hundred. Absolute certainty of 100% loss in value.
Since these numbers show the powers of ten you may have worked out that each step to the left reduces the risk ten times.
I have drawn a line at minus 2. this is a risk of one hundredth of a percent. I would define any risk greater than this as unacceptable. This is my arbitrary definition but it follows examples in other areas of risk study. Any institution would have to come to its own definition of unacceptable risk.
So between one hundred percent and one hundredth of a percent there is a range of unacceptable risk. Below ten to the minus six we have unreal meaningless numbers. Between ten to the minus two and ten to the minus six percent we have a range of real but acceptable risk.
Not surprisingly the average risks of being on the move are ten to a hundred times greater than those to do with sitting still. But they are still quite acceptable. All of the average risks are acceptable, but some of the worst case scenarios are not. These unacceptable risks are associated with the period of installation of an exhibition, with exposure to light, with pollution generated within show-cases and extremes of temperature caused by show-case lighting. The last three only affect certain types of object and the dangerous installation only occurs at certain types of venue. Let me illustrate these four extremes.
[Slides 14 Japanese exhibition installations ...people with ladders milling around chaos, confusion... aimlessly.]
This is the period shortly before the opening of an exhibition when everyone's schedules have slipped but everyone has to meet the same deadline. The courier must be brave and refuse to allow the object into this environment.
[Slides 15 Heals Archive Textile samples Chinese silk robe
We all know that some objects are sensitive to light. Some are so sensitive that only a couple of months exposure at 50lux will cause a noticeable change. Textile pattern books, especially those with fabric samples dyed with chemical dyes of the nineteenth and early twentieth centuries, will contain extremely sensitive material which has had very little exposure. The value of the samples is in the exact representation of their original colours. If they are put on open display the percentage loss in value will be enormous. Far greater than for some more exotic looking textile object where the dyes are more stable but have already suffered some changes as a result of long exposure.
Sensitive objects which are of archival value and have a limited exposure history should not be put on display anywhere, not in your own museum nor in anyone else's.
[Slides 16 Whole enamel pendant shattered enamel]
There are a small number of recorded cases where ceramics, rock crystal and enamels have been damaged by the radiant heat from sunlight or from spotlights. A surface temperature change of around 60 degrees centigrade is necessary but this is easily achievable with poor lighting design.
[Slides 17 Inro with lead inlay Lead objects from Museum of London]
The timbers and composite boards from which temporary show-cases are made give off volatile acids and aldehydes which can reach dangerously high concentrations. Natural history specimens, such as shells, and objects made of lead are particularly sensitive to these compounds. The results of reaction are usually crystalline or powdery white corrosion products. On the left is an example from the V&A which took about a year to manifest itself. On the right is an object that was sent on loan from the Museum of London to an institution which chose to disregard the Museum's specification for case construction. The effects can showed up within a couple of months. Since the cost of corrosion removal is a very high percentage of the value of the object it shows up as a substantial risk.
For objects that are sensitive and where the quality of the display environment cannot be guaranteed I would say the risk was unacceptable. One way round this would be to send the exhibits with their own environment. An environment you as lender are responsible for and feel comfortable with.
[Slides 18 Rosetti panels Boticelli]
There are other times when it will make you feel more comfortable to send objects with their own environment. Paintings on wooden panel are traditionally thought of as very sensitive to fluctuations in humidity. Despite their optimistic promises we know that many venues will not be able to meet even our relaxed environmental specification. The V&A now routinely lends panel paintings in microclimate cases. These can encase the whole object and its frame, as with the Rosetti panels on the left. Or they can be fitted almost invisibly into to frame, as with the Boticelli on the right.
[Slides 19 Paintings risk chart--on the move Paintings risk chart--sitting still
If you take a specific group of similar objects such as oil paintings then the range of magnitude of risk is smaller. That is, there is less orange showing on the chart. (less uncertainty)
If I had chosen specific objects for specific journey to a particular venue I could have further reduced that uncertainty. The average risks are all quite acceptable. Coming in third, winning the bronze medal, just behind fire and theft and just ahead of totally trivial is humidity fluctuation.
The notion that some humidity fluctuation is not such a great risk to oil paintings is something that is causing considerable controversy at the moment.
Since plus or minus five percent became the internationally accepted norm for humidity control there has been a growing feeling in conservation that somehow this is an absolute minimum standard, that we must strive to do better and that, if we fail, the objects will disintegrate before our eyes. By mindlessly reciting "plus or minus five, plus or minus five", or God help us "plus or minus one percent" ! And by refusing to be flexible in the interpretation of what are meant to be guide-lines, some conservators have done their profession a great disservice and have made others less willing to include them in the planning of exhibitions.
[Slides 20 Smithsonian graph 50% Smithsonian Graph 70%
An observation that any of us can make is that in fact there are large numbers of paintings happily living in environments that fluctuate around the range 35% to 65%RH without disintegrating. Recent research work by Mecklenburg and Tumosa at the Smithsonian Institute has given a scientific explanation for that observation.
The red curve shows how the strain in the pigment layers of a painting vary with changes in humidity. On the left hand screen we have a painting that has become acclimatised over a long period, many years, to 50% RH. If the humidity rises we develop a positive tension which could lead to cracking. If we decrease the humidity we develop compression that could lead to cleavage of the image layer.
But over a short range of strain all the components of a painting will behave elastically. That is, like a piece of elastic or a spring. If the applied stress is removed they will return to their unstressed state, undamaged. The limit to elastic behaviour is known as the yield point, shown by these lines here. This is not the breaking point but the point at which elastic behaviour gives way to plastic deformation, that is, irreversible change.
But within this range we can expect totally harmless and totally reversible changes in stress and strain in the paint layers. And as you can see this safe range of stress corresponds to humidity range of around 30-60% RH. A range much larger than the familiar plus or minus five.
But compare this behaviour with a painting that has become acclimatised over a long period to a humidity of 70%. At higher humidities the safe range for humidity fluctuation becomes much narrower. The range for a painting at equilibrium with 50% does not overlap the range for a painting at equilibrium with 70%. If you transfer a painting from one location, where the environment is in this range (30-60% RH), to another environment that is also somewhere in this range, there is a negligible risk of damage. However if you transfer a painting from a location with this environment (65-75%) to another location with an environment in this range, even though that may be at 50% ± 2%, there is a very high risk of damage.
[Slides 21 Selous painting Chew Manga sculpture
This is why this large unglazed painting (left) survived transfers around a range of galleries in Japan whose humidities ranged from 30-65%. Yet this polychrome sculpture suffered serious paint loss when it was moved from a cold damp church to a warm dry museum for the aptly named exhibition "The Art of Death"
I have shown the risk of earthquake as acceptable. This must be so, as serious museum professionals are acquiring valuable objects and placing them in museums in areas of high seismic activity.
[Slides 22 Kobe houses after earthquake Kobe fires after earthquake (slides borrowed from Jerry Podany)
This is what the city of Kobe looked like the morning after I had persuaded the Board of Trustees that there was no risk in sending paintings to Japan.
[Slides 23 museum in Kobe--fallen storage case museum in Kobe--showcase lighting diffusers smash ceramics
Even in Kobe, the risk of earthquake is small compared to the risks of fire or theft or humidity extremes. It's just that the risk of an earthquake is greater in Kobe than in London. We have sent textiles and paintings to the Hankyu gallery in Harbourland near Kobe since the recent earthquake.
[Slides 24 Left: Objects Assess * Condition * Exposure history * Differences Options Send * send own environment Don't send Right: People Understand * pressures * Motivations * Differences Respect * Opinions * expertise * The Decision Deserve respect]
I would like to summarize by saying that If you are planning an exhibition that involves sending your own objects out on loan or if you are planning to borrow someone else's objects, you need to do several things.
For the welfare of the objects, you need to assess the risks by looking at the objects condition, and the history of previous exposure to light and to humidity. You need to assess the differences between where the objects are now and where you want to send them. Then you have three options. In the majority of cases you will see that it is safe to send. If you are worried about large differences in environment you can overcome this by sending the object surrounded by its own familiar microclimate. In a few instances there are objects which are too fragile to send, or are in such pristine condition that they should not be subjected to the rigours of display. In which case everyone should be happy with the decision not to send.
Now, If you want to consider the welfare of the people, one way to make sure that everyone does remain happy with the decisions reached is to be sure that everyone understands what the benefits are and what the risks are. To do this people will have to listen to one another. They will then learn that other people are also under pressure from the deadlines of multiple projects. They will learn that other people have totally different but utterly valid reasons for wanting things to happen.
Out of this dialogue will come a respect for the different opinions of the various people involved in planning and preparation. With luck there will also grow respect for the professional expertise of the diverse members of the team.
And in that way all the members of the team will respect The Decision, whatever it may be.
But it is only by developing an informed and flexible attitude to the benefits and to the risks, that the individual contributors to decisions will begin to deserve respect.
By the way if you've begun to worry about the flight home. Just remember you aren't going to win the lottery either.
Timestamp: Sunday, 23-Nov-2008 15:20:04 PST
Retrieved: Wednesday, 16-Oct-2019 12:26:13 GMT