Elementary Particles: An Interview with Peter Brimblecombe

The kingdom of dust, which until recently represented the threshold of the visible, once extended to every nook and cranny of the world. Traveling by air, dust would land quietly and lay claim to the world around us—the gentlest form of ruination possible. Modern microscopes, easy-to-clean plastic surfaces, and new hygiene standards have challenged dust’s dominion. We now know what dust is made of, how to clean it, and even how to produce new forms of it, at times lethal. But though diminished in its scope, dust nevertheless remains.

Dust is an area of interest for Peter Brimblecombe, professor of atmospheric chemistry at the University of East Anglia. He has researched the many forms of decay, deterioration, and disintegration, including the blackening of buildings by pollution and the effects of such spoiling on public attitudes towards architecture. Much of his work has been on dust accumulation in Britain’s libraries and historic homes belonging to the National Trust. Brian Dillon and Sina Najafi spoke to him by phone.


Cabinet: Like most people, we’re not quite sure what dust is. To what extent is dust—library dust in particular—made of books and to what extent it is made of people?

Peter Brimblecombe: That depends on the collection. Obviously if you’ve got books with leather, then you have leather-rot and so on. But if you go into archives, where there are particularly few people, most of the dust is from boxes that are degrading. And in libraries in historic homes that have many visitors but where the books are not being read, where the library is decorative, then most of the contribution tends to be from people.


Does size factor into the definition of dust used in your field?

We’re interested in what we call coarse dust—dust that settles onto surfaces—which tends to be near five microns and above. In the health field, you’ll find people talking about respirable dust, which is often somewhat smaller in size. 


Is that because finer dust has no effect on the kinds of 
conservation projects you’re interested in?

It’s not well understood as of yet. All we know is that the dust that most influences the cleaning regimes in both libraries and historic houses is the settling dust, the coarse dust. That is the dust that costs money because it changes the appearance of things, which in turn drives the weekly cleaning budget. We’ve focused on coarse dust because of these financial considerations. The effects of finer dust are probably very long term: the gradual accumulation of soiling and the loss of contrast, the gradual blackening of papers or graying of light-colored materials, etc.


At what point does coarse dust become visible?

What we know is that in historic houses, cleaners see a surface as needing to be cleaned when the coverage is about three percent, though that’s very crude. It depends on the color of the dust, what kind of surface— shiny or flat—and so on. But cleaners behave in general as though three percent is undesirable. What we know about historic libraries, however, is that the cleaners call it “a little bit dusty” when about six percent is covered with dust. Once it exceeds six percent coverage, they start talking about it being “dusty” or “very dusty,” at which point they also express a desire to clean. You could argue that book cleaners are less sensitive than housekeepers who clean historic houses, but that’s due to visibility. The accumulation of dust on books and shelves tends to be less easy to see than the accumulation of dust on shiny furniture. Those are the kind of numbers that we derive from the habits of the cleaning staff, but it’s not really public perception. The cleaning staff is more house-proud than the average visitor, who doesn’t look as carefully. However, what happens with the public, which is particularly interesting, is that dust has both negative and positive aspects. The visiting public will often say, “Oh wow, the place was slightly dusty and the sunbeams gave it this enormous atmosphere of historicity. There was a wonderful evocative feeling of a building that was lived in,” and so on. And then we ask them later if there is anything we should do, and they respond, “Yeah, you should give it a decent mop and clean all the dust away.” So it’s a very difficult management problem knowing how to respond to these contradictory public desires. 


Is the public desire for clean historic homes due to the assumption that dust indicates neglect of the national heritage?

Indeed. They read dust as neglect.

Leaving aside aesthetics and public perception, could you clarify the actual effects of the dust we’re talking about?

In the public mind, we know that people view dusty properties as unhealthy for their visit. That’s probably not true but it’s definitely a strong public perception. Another perception, which is more the conservator’s, is that a dusty property is likely to have insect infestation, the argument being that dust provides food for insects. That’s probably also not true, though there are indications that some kinds of dirt, for example, grease, most certainly feed insects. So those are some of the misinterpretations about dust. But there is the real effect of the chemical damage caused by dust, which is not simply aesthetic. Dust allows corrosion products to build up, and being slightly hydroscopic, it also allows moisture to build up, which is another form of chemical damage. Dust also becomes very strongly embedded over time. If you leave it long enough, it becomes tightly bound to the underlying surfaces. So you’ve got to remove that dust to restore the artistic or the evidential value of the object, but if aggressive, the cleaning itself ends up damaging the object.


Does your research lead to guidelines for cleaners at historic libraries and homes?

There are two reasons you don’t want to clean frequently. Housekeepers cost money, and, second, you minimize the damage to the underlying surface by reducing cleaning frequency. We have really been trying to persuade housekeepers to leave things longer, to think more carefully about how the public views the property, not how they themselves view the property, to only clean when necessary. And that’s a very difficult battle because in many ways their whole existence is driven by keeping the property spic and span. So we’re trying to give them tools, like little speckly picture cards of dust accumulation where we can say, “You really shouldn’t clean until this point.” And the other thing we do is to try to lower the actual amount of dust that gets to the objects. For example, if the path you design for visitors to take on their tour moves them further away from an object or area, you lower the dust level. One interesting thing is that people release more dust when they’re very active, when they’re moving around jerkily, so you need to design nice smooth routes through buildings. But also people shed more dust at the beginning of their visit when they’re more excitable and pointing things out than at the end of a visit after thirty rooms when they’re beginning to get a bit tired of seeing yet another state bed. You’ve got two further options: getting people to be a little more tolerant of dust, or trying to sell dust as part of the visitor experience, as a way of conveying a sense of lived-in historicity. We’ve deliberately done this as a conservation practice but it also reflects how the house probably looked when it was being lived in. It probably wasn’t cleaned every day; it was probably cleaned once a week. In many ways, this daily cleaning regimen probably doesn’t reflect historic cleaning habits; but, to be fair, the visitor numbers today are also much higher than they would have been at the time.


There are numerous literary and historical references to the blackening of buildings and to the accompanying aesthetics of this process. In one of your papers, for example, you even cite Horace complaining about a temple being blackened. Does dust also have a long tradition of being discussed? There are scattered remarks about dust, such as Proust’s visitors noting that his house was so dirty that he had dust bunnies all over and he apparently even gave them names. But does the literature go beyond just anecdotes?

There are historic comments, and the most obvious ones relate to soot in terms of the use of indoor fireplaces. By Victorian times, the problem became so serious that you 
find that furnishings and wallpapers tended to be very dark-
colored in order to hide the dust. The exception was surfaces that could be washed very readily, like the antimacassar on the backs of chairs, which were white and stood out. There’s the whole question of finding your way around these very dark rooms, because not only were they dark but also they had very low-intensity lighting using candles or gas lamps. This is why they chose to have very bright white coverings, where possible. The other classic strategy was the use of brass indoors, which was very bright and stood out. But the problem goes way back. In the fifteenth century, you see that people will only bring out festive hangings at Christmas, for example, when they can afford to burn wood instead of coal, because wood produces less black soot and causes less damage to the hangings.


Of course, housekeepers have written about dust, especially late-eighteenth-century housekeepers, the kind that Jane Austen would talk about in Pride and Prejudice. Many housekeepers kept journals or books where they wrote in great detail about the removal of dust, how frequently it needed removal, and made quite thoughtful observations about dust. Some of the policies in National Trust properties in England have evolved from those housekeepers in the eighteenth century. We’re particularly interested in one of the eighteenth-century housekeepers, Susannah Whatman, who describes how you shouldn’t let dust settle because after a while it’s difficult to clean. As the wife of a wealthy paper manufacturer in the 1780s, she illustrates how the more thoughtful housekeepers have written very carefully about the problems of dust.


Historically, the word dust referred to all kinds of matter— most obviously, physical remains, corpses, but also to all kinds of dirt and soil. I wonder if you’ve come across the historical juncture where the word actually starts to mean specifically the kind of dust we’re talking about now.

I’m not sure at what point that takes place. Dust, historically, is not viewed very positively—think of “bite the dust” and other expressions such as “dusty old buildings,” and “dusty old books.” But there’s a real incongruity: dust is actually a very unusual word in that the verb can mean exactly the opposite depending on how it is used. “To dust” may mean to “clear the dust away,” or it may mean “to dust with snow” or “to dust with icing sugar.” So it’s an internally ambiguous word, one of only about a dozen such words in English that are internal antonyms. It’s interesting in that it reflects the whole ambiguity we have with dust in the presentation of our historic buildings—the sense of exciting mystery when the dust flies up and sunbeams look so lovely, and then as a sign of neglect. There’s an ambiguity in our modern approach, and there’s an ambiguity in the very use of the verb.


Maybe it’s appropriate to end on a very small note. Can we discuss dust jackets on books? Do they do what the name suggests or are they just a publicity stunt?

Despite their name, dust jackets are not very effective. What happens is that dust sneaks down and accumulates between the jacket and the boards of the book. Book cleaning staff hate dust jackets because you have to take them off, clean them, and then clean the internal boards of the book, which get little lines of dust around them. Dust jackets are quite a nuisance; they basically collect dust.