#224      28 min 44 sec
Radicals in the gallery: Scientists contend with nature's art vandals

Chemistry professor Carl Schiesser and art conservator Caroline Kyi discuss how understanding the effect of free radicals on pigment helps art galleries and museums preserve important works of art. Presented by Dr Shane Huntington.

"Some artists believe that the degradation process is part of the artwork and therefore the fact that the painting decays or changes colour is actually not detrimental in the eyes of the artist.  You know the question depends upon the work of art that the artist intended." -- Prof Carl Schiesser




Prof Carl Schiesser
Prof Carl Schiesser

Carl Schiesser is Professor of Chemistry in the School of Chemistry at the University of Melbourne and Director of the Australian Research Council Centre of Excellence for Free Radical Chemistry and Biotechnology.  He received his PhD in 1987 from the Australian National University and a DSc in 2000 from the University of Adelaide for his contribution to knowledge. Prof Schiesser is a major international player in the field of free radical chemistry with expertise that ranges from synthesis through to molecular modelling. In 2007 he was awarded  the A J Birch Medal of the Royal Australian Chemical Institute.

Prof Schiesser leads a team of researchers that are currently working on the development of new pharmaceutical products that combat the damaging effects of free radicals, the development of new reagents for the detection of free radicals, and the understanding of the role that free radicals play in the deterioration of cultural materials.

Prof Schiesser is a Fellow of the Royal Australian Chemical Institute and the Royal Society of Chemistry.

Publications

Caroline Kyi
Caroline Kyi

Caroline Kyi completed a combined Arts/Science Degree at Deakin University, Geelong (1997). In 2000 she completed a Postgraduate Diploma in Wall Painting Conservation at the Courtauld Institute of Art, London. Since then she has worked in Australia and overseas on the conservation issues presented by this form of immoveable heritage. Caroline has been involved in the teaching of conservation science at the Centre for Cultural Materials Conservation, University of Melbourne and is currently pursuing her research interest in biodeterioration of cultural materials by undertaking a PhD at the ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, University of Melbourne. Her thesis is titled, Controlling biodeterioration of cultural materials: The use of free radical-based treatments to inhibit communication pathways of microbial biofilms.

Credits

Host: Dr Shane Huntington
Producers: Eric van Bemmel, Kelvin Param
Associate Producer: Dr Dyani Lewis
Audio Engineer: Gavin Nebauer
Voiceover: Nerissa Hannink
Series Creators: Kelvin Param & Eric van Bemmel

View Tags  click a tag to find other episodes associated with it.

 Download mp3 (26.3 MB)

VOICEOVER
Welcome to Up Close, the research talk show from the University of Melbourne, Australia.

SHANE HUNTINGTON
I'm Shane Huntington.  Thanks for joining us.  Typically when we hear the term free radicals we're reminded of our health and the progression of age-related damage to our bodies related to these inconvenient molecules, but chemists look at free radicals in a very different light.  Not only are they critical to the way our biological world operates, but they also impact on non-biological materials that are all around us.  Paint is one such susceptible material that is of great interest to chemists and not just because of the vast consumer market for paint products.  Many culturally significant works of art are at risk because of the actions of free radicals.  Today on Up Close we speak to two researchers.  One, an expert in free radical chemistry.  The other, an experienced art conservator.  Together their meticulous understanding of the processes that damage works of art has led them to ways of both preventing and harnessing free radicals in art conservation.Carl Schiesser is Professor of Chemistry in the School of Chemistry at the University of Melbourne and Director of the Australian Research Council Centre of Excellence for Free Radical Chemistry and Biotechnology.  Also from the centre is Caroline Kyi, an art conservator and PhD candidate.  Welcome to Up Close Carl and Caroline.

CAROLINE KYI
Thank you.

CARL SCHIESSER
It's a pleasure to be here.

SHANE HUNTINGTON
Carl I'd like to start with you.  I think it would be great if you could give us an idea of what a free radical is and how this type of molecule compares to other molecules.

CARL SCHIESSER
Well a free radical is a molecule that through no fault of its own has lost an electron.  That could come about through, for example, ultra-violet radiation damage to molecules that you might find in your skin or molecules that are found in paint.  Some of you might remember from high school physics that electrons like to go around in pairs, so when a molecules loses an electron it becomes highly reactive and it spends the rest of its life trying to find a mate for this un-paired electron and in doing so when it interacts with a biological molecule can cause damage that could lead to diseases that are not necessarily treatable like cancers and when it interacts with materials such as plastics and works of art we start to see degradation of those materials.

SHANE HUNTINGTON
Many people have heard of free radicals in relation to their health and we're always being sold antioxidants and other materials that prevent the ravages of these free radical molecules, how are free radicals specifically bad for our bodies and would we be better off overall if these things just didn't exist in nature?

CARL SCHIESSER
Well it's a double-edged sword really.  I mean free radicals are important signalling molecules for many biochemical pathways.  For example nitric oxide is used to regulate and control blood pressure and some free radical processes lead to reactive oxygen species that can combat the effects of bacterial invasion that might come about through some sort of infection process.  So from that perspective we can't get rid of free radicals, but on the other hand free radicals can also cause, if untreated and not dealt with very well, can also lead to inflammation and the sorts of diseases that I alluded to earlier and you know antioxidants are common molecules that are found in foods like vitamins - vitamin C, vitamin E.  They are often added to foods to help us live a healthier life, but you know recent studies have suggested that a lot of these added antioxidants have really no dietary benefit because they don't actually get to the site where they're required to combat the free radical damage.  I'm a little bit sceptical.  I think the jury's out on whether or not added antioxidants in your diet actually have any benefit.

SHANE HUNTINGTON
Now we've no doubt evolved with these free radicals in our environment, what about other species and other, you know, plant species and so forth in nature?  Are there similar interactions with free radicals across the biosphere?

CARL SCHIESSER
Most living organisms, as far as I'm aware, have developed some sort of defence against free radical damage and no organisms voluntarily wish to die.  So you'll find, for example, kangaroos - all marsupials for that matter - have developed enzymes that can actually repair the damage associated with free radicals that are produced through sunburn.  Now don't ask me why kangaroos still have these because they have fur so, you know, the likelihood of them actually suffering free radical damage caused by ultra-violet radiation is quite low but they still have this enzyme that other mammalian species have evolved out of their biology and I also believe that some bacteria also have these enzymes.

SHANE HUNTINGTON
Now these molecules don't just affect the biological, they also effect man-made constructions.  Where would we see these sorts of effects?

CARL SCHIESSER
In many places.  I mean the most obvious place would be in the brittling of plastic.  If you've left plastic out in the sun and it makes them easier to break.  Once you've painted your walls a nice white colour, over time it starts to yellow and that's due to free radical interactions with the pigments contained in the painted materials and that's again caused by UV damage and free radical mediated processes.

SHANE HUNTINGTON
So on the molecular scale there where in the example of the paint work and so forth is exposed to UV radiation from the sun, what's actually happening with the molecules in that area upon exposure that leads to free radicals and the damage?

CARL SCHIESSER
The majority of these paints contain polymeric materials - large molecules that essentially hold the fabric of the paint together.  When exposed to UV damage - ultra-violet radiation are high energy photons and when they hit these molecules they can cause bonds in the molecules to break.  The result of that are usually the formation of free radicals within the paint matrix and then we get all sorts of processes occurring subsequent to that.  Reactions known as beta scission processes which actually will further degrade these polymeric molecules and also reaction with oxygen.  Oxygen is all around.  Oxygen is quite paradoxical.  It is itself a free radical in its ground state.  It can react with these molecules and lead to a whole set of deleterious functional groups being generated within the framework of the polymer.

SHANE HUNTINGTON
Caroline let's turn to your area of expertise which is art conservation.  When we talk about damaging paint, what sort of damage do you see in art works relating to this free radical chemistry scenario?

CAROLINE KYI
Relating to the free radical chemistry, as Carl has mentioned, free radicals can be advantageous or disadvantageous depending on where they're introduced and the environment around them.  For example oil paints, they polymerize or form a film in what we would say were dry in response to free radical reaction, so that formation of an oil paint film is based on free radical chemistry.  If the free radicals weren't there we wouldn't have a film forming so obviously we want the radicals present in that type of chemistry.  On the other hand, for example, paint isn't just a colorant or a pigment and the binder media which is like the glue that carries the pigment, there's also additives to that paint and then we enter the realm of proprietary materials and often when conservators are confronted with an artwork where there's a problem with, for example, the paint layer, we want to go to the manufacturer and say what did you put in it?  What's the underlying chemistry that's being developed to create this product?  Often we can't get that information so then it becomes problematic because we don't know what's been added because certain pigments can enhance radical driven reactions to cause powdering and flaking of paint layers.It also depends where the artwork is housed.  If the environment has high humidity and in direct sunlight then you're adding other variables that can enhance free radical associated damage.  So it's a combination of things.  It's the paint to begin with - the quality and what the additives are - the chemistry of all those additives combined and the environment and that results in an art object or objective of cultural significance presenting damages or otherwise.

SHANE HUNTINGTON
I'm Shane Huntington and my guests today are chemist Professor Carl Schiesser and art conservator Caroline Kyi.  We're talking about free radical chemistry and art conservation here on Up Close.  Caroline you mentioned the possibility of artworks being either in, you know, these nicely controlled - humidity controlled - environments like your gallery, but then you have ones that are outside, your sort of exposed artworks.  How does the challenge in conserving these against this sort of damage compare between these two environments?

CAROLINE KYI
Oh it's significant and my interest in terms of conservation and my specialisation is actually in wall paintings so I'm interested in immovable heritage in general and the conservation issues that are presented when you can't take an object out of its environment and all the dynamic systems it operates in.  For examples environments with high humidity and humidity is actually a significant factor in lots of forms of deterioration.  For example I was working in Egypt recently and where it is quite dry - even though it's quite hot, it's quite dry - and they have mud sort of shelters to keep excavated fragments of wall paintings and pottery in there and everything was in amazingly good condition.  Why?  Because of the absence of humidity or moisture in the atmosphere.  Where you go to somewhere like Asia where you've got a high humidity, objects of a similar age would just be in a really precarious condition because of the impact of the humidity and also fluctuations in environment as well.Sometimes it's not the most advanced method of controlling environments, it's often common sense and having a regulated environment and often choosing materials that are local and have sort of a historical integrity in the sense that - for example - lacquerware works well in Asia, so we see those materials work for artefacts in ways that modern materials or western materials originating outside of that culture or outside of that locality don't, so it's a selection of materials by the artist that work in the environment and then creating an environment that's stable and hopefully reduced in humidity.

SHANE HUNTINGTON
Now when it comes to the sort of damage to paintings, it's not just the free radical scenario is it?  You're also getting what would surprise many people, the effects of both sort of bacteria and fungi acting on these paintings.  Explain how that works because it's not something that most of our listeners would expect to find on artwork.

CAROLINE KYI
It's something, even for conservators, that becomes apparent when you see the symptoms which are usually in the form of mould growing across a surface and again these types of deterioration are more pronounced in environments where there is high humidity.  What actually happens is when you see mould on a surface it's actually the result of a process that is believed to originate with bacteria.  So bacteria are primary colonisers to the surface and often they have limited nutritional requirements so they may even be able to establish themselves on inorganic materials.  Once they've established themselves and they develop a biofilm they may produce acids that may attack materials.  Obviously you have their waste products being released and also their cellular waste and then you have organic fodder for subsequent organisms to come along so you get the successive colonisation happening and then ultimately it's proposed that a combination of added materials from the environment might be involved and then ultimately you get this deterioration of the artwork.So deterioration can be aesthetic damage.  You can get staining of the surface due to pigments being produced by organisms and you can also get physical damages as structures from mould and fungi penetrating to the surface.  So yes, they can cause significant damage and as I've said in areas where there's high humidity, it's more significantly pronounced.

SHANE HUNTINGTON
Now in terms of studying these particular biological contaminants are you able to take them from the paintings, grow them up in the lab and study them?  Is that a possibility with these materials?

CAROLINE KYI
It is a possibility and that's actually something we've been endeavouring to do.  So what we've done is take some sacrificial cultural material and we've used them to create a cultural materials broth.  We've run this broth, which is sort of a representative broth of organisms isolated from artworks to test for their response to nitric oxide in an attempt to control biofilm formation.  That being said it's very difficult to cultivate organisms in the lab.  Usually it's difficult to cultivate the organisms you want too because quite often plates get contaminated and techniques like PCR - the process whereby the genetic material of organisms that may not be able to be cultivated in the lab is isolated and we can get a general idea of what organisms are present, but obviously thrown up due to standard cultivation techniques.  So while in an ideal world we'd like to identify all the species that we're looking at, we have a representative community that we can work with which is probably the best we can hope for and we're seeing a lot of parallels with model cultures as well.  So yes we have been taking organism from artworks.

SHANE HUNTINGTON
Carl, Caroline mentioned the role played by nitric oxide in the distribution of these biofilms on certain artworks.  How does that work?  What is actually happening with these particular molecules?

CARL SCHIESSER
Actually the exact mechanism for how nitric oxide controls the signalling processes within biofilms is not really well understood.  What is unknown is that at certain concentrations these organisms release nitric oxide to signal to the colony that the food has run out and so we need to disperse.  At other concentrations the nitric oxide is used to give the signal to the colony that there is a source of food and that we should grow at that particular location.

SHANE HUNTINGTON
Caroline given we know that nitric oxide is involved in these particular signalling pathways for these films are we able to utilise that to protect the artworks that you're talking about?

CAROLINE KYI
Yes, we're attempting to do that at the moment.  We're using a model organism Pseudomonas aeruginosa.  So what we're doing with that organism is trying to study a bio-remedial approach using nitric oxide.  So this particular species reduces nitrate to nitric oxide so it can effect - produce nitric oxide.  What we hope then is if we can trigger or upregulate these organisms to produce nitric oxide then they will release into a system and cause dispersion of biofilms.  Now these types of organisms - there are other organisms obviously outside Pseudomonas that can do this - have also been identified in populations removed from cultural materials, so what this implies is that we may have a biofilm that's made of nitrate reducers or nitric oxide producers within a general population of organisms.  If we can upregulate those organisms present in the biofilm to produce nitric oxide - if nitric oxide is read among the community as a universal signal for dispersal - then this can enhance biofilm dispersal.What this then leads to is the fact that if you destabilise a biofilm and reduce its integrity it enhances its susceptibility to treatments with antibiotics and bio-science.  Now I've spoken to other conservators about this treatment approach and some of them say well you know this seems like an extreme measure to take, but most people when they think about artworks they're thinking about a painting or a manuscript.  When you're dealing with an immovable heritage - large monuments, wall paintings, sculptures - the toxicity load of using lots of biocide is significant.  If you can reduce that load, that makes a treatment more, or permission and it may even reduce the periods in between treatment because unlike objects that are housed in museums where you can often treat and then put them in a stable environment and they won't require subsequent treatment for a long period of time, immovable heritage - especially if it's outdoors - often requires repeat treatments.  So what we want to do is modify or improve or develop the best approach to repeat treatments that are necessary.

SHANE HUNTINGTON
Presumably this grabs a whole range of culturally significant works that previously were outside I guess the cost base of what could be treated and allows them to be considered for treatment as well?

CAROLINE KYI
Yes and we're hoping that it will provide, potentially, a prophylactic measure because we've seen from some of our results that - so say a treatment proposal would be to treat with a biocide and follow up with a nitric oxide based treatment because nitric oxide can reduce biofilm formation at the onset as well as cause dispersal when the biofilm is established.

SHANE HUNTINGTON
I'm Shane Huntington and my guests today are chemist Professor Carl Schiesser and art conservator Caroline Kyi.  We're talking about free radical chemistry and art conservation here on Up Close.  Carl does the old phrase they don't make them like they used too, when we look at some of these paints that are currently in use today, how do they compare in terms of their longevity to some of the oldest paints that we get to examine?

CARL SCHIESSER
I think it's fair to say that back in the good old days, you know the masters would make their own paint and they would meticulously grind the pigments and they actually knew the skill to actually create a medium that would be long-lasting and so you can go and look at paintings that were made, you know, many centuries ago and they're still in fairly good knick.  The onset of twentieth century paint is where the problem lies because, you know, around about the 1950s there was a whole series of synthetic polymeric materials that are based on acrylic or maybe they were based on acetate.  They became available, largely for the housing industry and for the automotive industry, and they provided a colour palette through the use of synthetic pigments that were not available prior to that at a reasonable cost and so while you ended up having new walls painted in your house with new types of colours, the artists saw that as a great opportunity to create new works of art using these materials despite the fact that these materials had been largely developed by the paint companies to not last more than about 20 years.You know you expect a paint on your house to last 20 years maybe if you're lucky and then you'd re-paint your house.  You don’t' really expect that the paint on a painting that an artists has created to last 20 years.  You want it to last a lot longer than that and unfortunately the artists, I believe, really got into the use of this paint before the degradation chemistry of this paint was well understood and that's where the major problem lies.

SHANE HUNTINGTON
So if you were to design a paint specifically for the art community what sort of attributes would it have and how would that compare to those used, as you say, in the housing industries?

CARL SCHIESSER
That's again a difficult question to answer because it depends on the artist.  Some artists would like their painting to last forever and so you want to have a very, very stable paint to create your work with.  Some artists believe that the degradation process is part of the artwork and therefore the fact that the painting decays or changes colour is actually not detrimental in the eyes of the artist.  You know the question depends upon the work of art that the artist intended.

SHANE HUNTINGTON
Carl how do we go about investigating paints and their stability?

CARL SCHIESSER
Well we've developed methods within the centre that I’m involved in to actually directly assess free radical damage to polymeric materials with the use of probes that were also invented within the centre, but up in Queensland, and these probes are able to detect free radicals and oxidative stress through fluorescence techniques.  These compounds that are known as profluorescent nitroxides through quantum mechanical effects are actually not fluorescent in the presence of a free radical, so we make stable free radicals that contain these fluorophores.  When they detect a free radical basically the light bulb is switched on and the fluorescence intensity is directly proportional to the number of free radicals that are being detected.  So we are involved in research at the moment where we are in fact embedding these sorts of materials into existing paint formulations - and we can't do it invasively in existing works of art, but we are simulating the sorts of paints that artists used over the last 50 years.  We're embedding these.  We are artificially accelerating their damage and we're exposing them to different humidity levels with the idea of trying to work out what is the real issue in terms of a free radical basis.Is it where two different types of media contact?  Is it due to where the cracks are formed?  Where the brushstrokes haven't been quite perfectly made?  We were just trying to get a good idea of that process before we can even advise a paint company what to do about it.

SHANE HUNTINGTON
I'm very interested in this idea of simulating the environment that you will one day put the paint into.  How do you go about doing that so that you can answer the question, what will this look like in 20, 30 or 50 years?

CARL SCHIESSER
Well it's often difficult to find out the exact formulation of a paint as Caroline alluded too.  I mean some of these things are proprietary, so if the paint that you're interested in is, for example, polyvinyl acetate then you have to make a reasonable judgement about what might be in the polyvinyl acetate that a particular work of art was made out of because it's unlikely that you're going to get the exact formulation.  So the idea would be to perhaps make your own polyvinyl acetate.  You might want to put a pigment in there that was used by the artist or used by artists in general and you might want to put some other things in there that might be biocides that are often found in these paints and also molecules called HALS - hindered amine light stabilizers - that counteract the effect of UV damage.  So you would formulate this up according to the practise that might have been used by a particular artist.  You make a painting - a model painting - of course it won't be as good as the original artist's model painting and then you'll go about assessing it.  You might put it on canvas, you might put it on glass, you might put it on metal and assess the performance of these new materials under various conditions.

SHANE HUNTINGTON
Given all this knowledge that we have is there any sort of move towards, I guess, a renaissance in the way paints are made by a particular artist?  Are they going back to making them themselves in order to, you know, get the sort of longevity that some of them would require?

CARL SCHIESSER
It's interesting I've actually spoken to a couple of artists about that exact issue and it's one of costs really.  I mean artists are often - especially when they're starting their careers - poverty-stricken and so they're not really all that interested in using the best quality paints.  They're more interested in being able to create the image that they are wanting to create or the object that they're wanting to create using what's affordable to them.  That may mean that they will be using perhaps not the best quality paint.  There are paint companies out there who strive to make high quality paint and actually looking at research to improve the quality of their paint.  I think, you know, it depends on the artist and whether it's actually important to them.  You know, so for example I spoke recently to an artist who was very, very keen to get an infrared paint.  Doesn't want a paint that actually does anything in the visible regions.  She wants to actually be able to overlay a work of art on top of another work of art and you put on your infrared goggles and you see something different.

CAROLINE KYI
Because it's also about the effect that the artist wants to generate and we might say to them this paint or paint manufacturing company may say this paint is really good, proven to be this durable and they're saying but I'm not getting the effect that I want.  I want a thicker texture, I want a brighter colour.  So it's that as well and often I think for the artists it's about the visual effect as opposed to the longevity of the artwork.  But then if it was the other way around maybe conservators wouldn't have jobs.

CARL SCHIESSER
I think what's important here is not so much to come up with a new product, although that's not a bad thing, but I think the important thing here is to provide information for the artists.  I think that's far more important so the informed artist can say well if I choose product (a), you know it's only going to last this long and that's not really what I had in mind, maybe I should go out and source a different product.  So I think it's enriching the information database.  It's far more important than actually providing a new product for general use.

SHANE HUNTINGTON
Caroline I can imagine one of the benefits of all this knowledge is you're better able to capture particular works in the state that they're currently in with the knowledge that because of the materials used they may not last that long.  Is that one of the things that you're sort of doing with this knowledge? Making sure that we have good records of many of these, especially external artworks?

CAROLINE KYI
It's having good records and looking at the treatments and the conditions under which they exist.  If you have a representative profile of a series of artworks, you know the original materials, the conditions, their treatment history, you can begin as with all scientific processes to see patterns emerge and that informs us for subsequent treatments.  Also I'd like to say something with regards to this concept that previous artists or artists during the renaissance had it completely under control in terms of the materials they were using.  It's not necessarily true.  If you take The Last Supper by da Vinci, that for him was an innovative work where he was trying new materials hence the problems that they have with the artwork today.  Again, a lot of artworks where artists may have employed techniques that weren't standard or widely used, they are unlikely to be around today so there is this constant desire or need by artists to experiment but during the renaissance people - they understood their materials.  They knew what worked and that's why the fresco palette employs a certain amount of pigments because it has to be compatible with the alkaline conditions of fresco media.  So this sort of balance between knowing your materials and knowing the limitations and this desire - I think it's a human desire to experiment - that's part of the creative process for an artist.  So that's where we're at with conservation.  We've got to take into consideration the chemical and physical properties of the materials, but also the artist's sort of intention and their desire to create a certain effect.

SHANE HUNTINGTON
Professor Carl Schiesser, Professor of Chemistry in the School of Chemistry at the University of Melbourne and Director of the Australian Research Council Centre of Excellence for Free Radical Chemistry and Biotechnology and Caroline Kyi, also from the Centre of Excellence for Free Radical Chemistry and Biotechnology, thank you both very much for being our guests on Up Close today and talking about free radicals and art conservation.

CARL SCHIESSER
It's been a pleasure.Thank you.

CAROLINE KYI
Thank you.

SHANE HUNTINGTON
Relevant links, a full transcript and more info on this episode can be found at our website at upclose.unimelb.edu.au.  Up Close is a production of the University of Melbourne, Australia.  This episode was recorded on 31 October 2012.  Our producer for this episode was Kelvin Param.  Associate producer Dyani Lewis.  Audio engineer, Gavin Nebauer.  Up Close is created by Eric van Bemmel and Kelvin Param.  I'm Shane Huntington.  Until next time, goodbye.

VOICEOVER
You've been listening to Up Close.  We're also on Twitter and Facebook.  For more info visit upclose.unimelb.edu.au.  Copyright 2012, the University of Melbourne.


show transcript | print transcript | download pdf