Tag Archives: Plastics

Raspberry Pi Project – 1st video

*Head over here to see the latest blog post. 

Last July I wrote about our project using a raspberry pi and its camera module to track the decay of a plastic handbag. The project has been running for about 4 months now and we complied the first video not so long ago.

To be honest we were more than a little nervous about this project, as to us, little if anything had happened for the majority of the summer, but as the seasons changed a few things started to happen!

So a number of things are pretty clear from the video – the major one being that it’s not as dramatically catastrophic as we had hoped! Ironically the video doesn’t pick up on the areas most changed – like the great big hole on the lower left side that is blocked by the beehive bag, nor does it pick up just how many crystals have formed as they are mostly on the sides. The second is that the limitations of the camera module mean the resolution is low – but for a £25 camera it’s still good enough to give up some great information.

The sides of the bag have had seen a large formation of crystals over the three months

The sides of the bag has seen a large formation of crystals over the three months

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The large crack on the bottom edge of the bag on the left side of the image (proper right of bag) is not seen forming on the time lapse as its photobombed by the edge of the beehive bag

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The beehive bag, which I’ve talked about before, is still falling apart! Originally one side broke apart faster that the other, now that ‘better’ half is breaking up. The main crack in the bottom of the picture was only a hairline fracture at the start of the timelapse.

If you look at the video closely you will notice two things of real importance. Firstly, each of the cracks that were present at the start have gotten a little bigger and the delamination of the bag is wider. Remember that we are looking at two months data over a 3 month period, so for things to get noticeably bigger in this timeframe is a real shock in a museum environment. The second thing to notice is the way the cracks grow. If you look closely at the top right corner of the bag you will see the shadow and highlights expand and contract. We also see the beehive bag expand and contract. This might be due to the environmental conditions of our science lab and could be what is ripping our bag apart.

Our next job is to try and improve the video quality and also relate the visual information gained to the data from our environmental monitoring system. From this we may be able to come up with an insight into the storage of plastic objects.

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So what are you doing with a science degree in a design museum…

*NOTE – So the lovely people in the media department at the V&A have asked me to blog for them. This is a great opportunity for my work to reach a much larger audience! So I will be posting to the V&A blog 1st and then a little later I will post here. If you wish to keep up to date then check out my newest post over on the V&A Blog 🙂

At the very beginning of my internship I posted (in rather mushy way) about the FTIR machine that we have here in the lab. We have quite a good setup here and over the past number of months I’ve been trying to take every advantage I can to use it.

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A close up on the microscope with the sampling cell (silver disk) in position. Using a microscope we can pick out areas in a sample to take out measurement from. (c) Victoria and Albert Museum, London.

FTIR stands for Fourier Transform Infrared Spectroscopy; but what that really means is that it uses an Infrared energy beam to excite the molecules in a material. These molecules absorb part of the energy and with some fancy maths (god bless computers!) we end up with a spectrum from which we can tell a hell of a lot about the material. In a similar way to how bridges resonate at certain wind speeds or a singer breaking a wine glass, the atoms in the molecules vibrate at defined wavelengths. This means that on our spectrum each peak is associated with a certain type of bond.

So what has all this got to do with the conservation science dept. at the V&A! Well we come across a lot of waxes, resins, varnishes, and of course plastics (which is what my internship is about) in the collection. The identification of these materials is important because it not only helps us in carrying out conservation treatments, but also in building up general knowledge and information about the lives of our objects – like on the trade routes used in their manufacture. We can also learn a lot about the decay of objects by looking at peak ratios or the formation of new peaks.

We use two main methods here in the lab which I like to think of as the “quick and dirty” or the “long, but fun” methods. The “quick and dirty” method is technically known as Attenuated Total Reflection (ATR) and works by the phenomenon of total internal reflection. I call it quick and dirty because the sample prep time is quite short – you only need to place the sample on top of a sampling cell that is about 2mm2. It’s dirty because the quality of spectrum is very dependent on external factors like having a uniform thickness, having the correct pressure over the cell, having a uniform sample and most importantly having enough sample to cover the entire cell.

The “long, but fun” method is called transmission as the light source goes through the sample. This method can lead to a spectrum that is clearer and stronger than ATR but is long because of the sample preparation. First one must mount a sample onto a diamond cell.

A little size comparison - the total size of the diamond sampling cell is just smaller that a 5p piece, however we only place the sample in the small clear square. We really only need a tiny sample to make our measurements. (c) Victoria and Albert Museum, London.

A little size comparison – the total size of the diamond sampling cell is just smaller that a 5p piece, however we only place the sample in the small clear square. We really only need a tiny sample to make our measurements. (c) Victoria and Albert Museum, London.

Unlike the ATR method, transmission only needs a tiny sample (size region: grain of fine sand). The small size requirement is due to the ability to use a microscope to focus on an exact spot to analyse. The down side to using a microscope in this way is that you need to align everything correctly which takes time! The fun side is this method requires the detector to be cooled via liquid nitrogen…see my previous post for the fun we have!

An example of the differences between the two methods is perfectly demonstrated by an object we analysed that was treated by Camille Devilliers, an intern in the sculpture conservation department. Camille had a terracotta that had split in half and had been previously repaired by ‘cementing’ two iron dowels into the back of the object. Camille needed to know what the material holding the dowels in place, and what were the other materials used in the previous treatment.  With these pieces of information she could select the correct method to remove the dowels without damaging the object.

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The back of the terracotta that Camille was working on – you would be able to see two iron dowels if they weren’t covered by the brownish beeswax in the center of the object. (c) Victoria and Albert Museum, London.

The graph below shows two spectrum of the same sample from Camilles terracotta – one taken using the ‘short and dirty’ method (shown in red), the second spectrum, in blue, results from the ‘long, but fun’ method. Looking at the graph it’s easy to see that the strength of the red line is much less than the blue; what’s not so easy to spot is that the peaks don’t exactly match – the red peaks are shifted slightly compared to the blue peaks. When we come to search against the database we see that the red line has an 89.23 match with Beeswax AND with Carnauba wax. This isn’t what we like to get when we search! Thankfully if we used the ‘long, but fun’ method we see that the blue line had a 98.25 match with Beeswax and the first 5 results were all forms of Beeswax; no Carnauba to be found which is perfect!

FTIR WAX

Spectrum comparison – You might need to click on this image to get a better view of it 🙂 (c) Victoria and Albert Museum, London.

This clarity is whole ball game! When we look at more complex spectra or something that is a mixture, the greater the strength of the sample and the non-shifting peaks means it can be far easier to identify the material.

Mini Post No. 6

So I have been researching about Polyvinyl chloride (PVC) over the past while and I came across this lovely example in the lab of the major danger associated with PVC. Many of us have our family photos kept in ‘plastic’ photo albums – most of these are going to be made from PVC. The biggest danger to our valuable family photos isn’t fire or theft, its the album itself! The plasticizer is very prone to migrating to the surface of PVC, if it’s not removed it forms what’s known as sweat beads. These beads destroy photos! Take a look at the two images below to see just what kind of damage can be caused!

Later in the month I’ll do up a more detailed blog post about PVC. Till then, if you want more information about how to protect your photographs have a look what the British Library and The National Archives have on the topic.

A photograph has been totally distroied by the migraetion of plastizer from the album sheets. (c) Victoria and Albert Museum, London.

The photograph has been totally destroyed by the migration of plastizer from the album sheets. (c) Victoria and Albert Museum, London.

Close up on the face of a person in the photograph. The image had lost almost all definition. (c) Victoria and Albert Museum, London.

Close up on the face of a person in the photograph. The image had lost almost all definition. (c) Victoria and Albert Museum, London.

 

Kaleidoscope House – A dolls house for the ‘child’ interested in modernist architecture

One of the nicer elements of my job is the exposure to the wonderfully diverse collection that we have here at the V&A. Later in the year the Museum of Childhood is putting together a wonderful exhibition on Dolls houses. We (my supervisor and I) were asked to consult on one of the more unusual dolls houses that will make up the exhibition – Kaleidoscope House

Kaleidoscope house - a mini modernist masterpiece (say that 10 times fast!)

Kaleidoscope house – a mini modernist masterpiece (say that 10 times fast!)

The example of Kaleidoscope House that we have here at the Museum of Childhood does not have its artwork attached to the walls. As they were purchased separately the museum could not, in good faith (ethics and all that!), adhere the artwork to the plastic walls without investigating how the artwork, adhesive and plastic would react over time. I was set the challenge to devise a simple and quick experiment to do this.

When we talk about the lifetime of a collection or an object we need to look timelines beyond our own lifetimes or careers. Research into this topic indicates that people would like an object to survive in a “usable” form for 100-500 yrs. Clearly we can’t wait around to see how objects react to their environments, nor can we always look to the past as we may not know the exact conditions of storage. This is where artificial aging comes into play. We know that exposure to light, especially UV light, is very damaging to plastics (and to objects in general. I can’t believe I just linked to the Daily mail…). We also know roughly the amount of light an object will receive when on display:  50 lux for 10 hours a day for 365 days = ~180Klux per year. By placing objects in a light box, exposing them to very high light levels we can mimic the the effect of years of light exposure in a short period of time. There are other factors which are important, temperature and relative humidity being the other two major effects. I wont go into more detail and risk boring you all but Robert Feller has a very good book on the topic of Accelerated aging which you can find for free here and it’s well worth a read, even if it’s just to brush up on the basics of what tends to age things!

Anywhos… back to my plastic dolls house. Through a bit of research – basically procrastinating while reading the wonderfully in-depth world of mini modernist houses over at http://modernminihouses.blogspot.co.uk/ we confirmed our theory that the walls were made of polystyrene, a common plastic used for this type of application. The experiment was a simple idea – get materials similar to those intended to be used, test a range of different adhesives and expose everything to 5 years’ worth of light! CD Jewel cases are also made of polystyrene allowing us to use cd cases that we had here in the lab – to better match the current conditions of KH we used cases that were of similar age. The amazing people over in the paper conservation department gave me some mount board of a similar thickness to the artwork; they also provided three common adhesives used in paper conservation – wheat paste, EVA and Methyl cellulose. The other interesting adhesives we tested were blue tack (yup, regular blue tack!), Paraloid b72 (a very common adhesive used in conservation) and Sugru (a new silicon based adhesive a bit like blue tack, only yellow and much stronger/permanent. It is also very popular in the hacking community atm.)

CD case ready to be tested - note that I used an excess of adhesive to see the 'worst case scenario' when trying to remove the 'artwork'. In real life you would try to use much less adhesive than this. (c) Victoria and Albert Museum, London.

CD case ready to be tested – note that I used an excess of adhesive to see the ‘worst case scenario’ when trying to remove the ‘artwork’. In real life you would try to use much less adhesive than this. (c) Victoria and Albert Museum, London.

CD jewel cases in the light box, propped up so that front and back get similar light exposure. You can see that a few of the adhesives have failed right from the beginning! (c) Victoria and Albert Museum, London.

CD jewel cases in the light box, propped up so that front and back get similar light exposure. You can see that a few of the adhesives have failed right from the beginning! (c) Victoria and Albert Museum, London.

After leaving the test to run for 96 hours (who wants to do the math to work out the average light levels in the light box…) we then tried to remove the mount-board and the adhesives. Before starting the tests I thought that wheat paste would work the best – how wrong was I! It was the 1st to fall off, along with Methyl cellulose – they didn’t even last a day!

Sugru was very difficult to remove, and I really thought I’d crack the plastic – I didn’t, but as you can see below I couldn’t remove the mount-board cleanly. Removing EVA was very similar and the risk of cracking the plastic rules these two adhesives out of contention.

Sugru...I was able to remove this from the plastic CD case, but not the paper artwork - it wouldn't want to be a Constable painting i was trying to take off! (c) Victoria and Albert Museum, London.

Sugru…I was able to remove this from the plastic CD case, but not the paper artwork – it wouldn’t want to be a Constable masterpiece I was trying to remove! (c) Victoria and Albert Museum, London.

Blue tack left a nasty residue behind. Researching into what goes into blue tack we found out that it contains a small amount of Xylene. Have a look at the video below to see what happens (admittedly in a pretty extreme case) when xylene and polystyrene come into contact with one another! Not what you want to have happen and leaving the residue on the surface would increase the risk of localized damage to the object.

You can clearly see the residue left behind on the surface! (c) Victoria and Albert Museum, London.

You can clearly see the residue left behind on the surface! (c) Victoria and Albert Museum, London.

So after all that work we found out that none of the major adhesives were suitable for this project (what was it that Thomas Edison said…) . In fact some of them could have totally ruined our lovely dolls house! The curators were thankful for the information we had given them, but also a little sad as they are now back to square one. We think we might be able to hang some of the artworks using nylon wire (again, a pretty common thing to do). The risks to the object are increased the more times the blue roof has to be taken on and off, but it also means we won’t have access to hang every piece of art. A small price to pay for keeping this lovely object in great condition! You can come see what methods we used when the exhibition opens later in the year.

Beginnings…

I suppose it’s best to begin at the beginning – My name is Mark Kearney and until a short time ago I was living the idyllic (yet unemployed) country life on the west coast of Ireland. That was until I moved over to London to start work at the Victoria and Albert Museum. I have been lucky enough to be chosen to be the Institute of Conservation/Heritage Lottery Fund intern for Modern Materials (Plastics) at the V&A. The move over hasn’t been as smooth as I’d have liked and I have discovered the joys of house hunting in London! But that has finally been sorted and I’ve a place to live!

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Sunset on the Northwest of Ireland – Not exactly my backyard, but not far from me either.

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Cherry blossoms at South kensington tube station the week I started work.

My background is in Astrophysics – a subject many think is light years away from conservation. I spent a lot of my time in physics looking at fancy images of the sun with the help from the lovely people over at Solar Monitor.

I got into conservation because I have always loved museums, art, design and old things in general! When it was coming to the end of my undergraduate and careers had to be picked, I wanted to find something where I could combine all the science I’d learnt with my interests in art and design. Conservation was an obvious choice for me (I’m also nosy and I wanted to find a way round the ‘do not touch’ signs you see in museums).

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One of the many “Do Not Touch” signs here at the V&A. (c) Victoria and Albert Museum, London.

This internship is going to be mostly focused on the conservation of plastics, a material that most people think lasts forever, but some, in reality have a very short life. I will pepper the blog with images, analysis spectra and as many interesting things as I can find. The blog is going to be a record of the work I do over the coming year and I’m going to try and keep it as informal as I can. I will post links to websites where you can go into a bit more detail if you wish, but I will try keep this blog as easy to read, yet with as much real substance, as I can.

I started the internship a little over a month ago and thanks to the fall of bank holidays, some long meetings and a training day I’ve only had one full weeks work yet! (Talk about soft landings!). So far, a lot of time has been spent getting all the ducks in line for some of the work I want to do during the year. I have also been getting used to some of the high-tech gadgetry the Conservation Science department has. Over the next year you’re going to hear me talk a lot about FTIR spectroscopy.

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The FTIR machine we use here with its fancy microscope attached. (c) Victoria and Albert Museum, London.

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A typical FTIR specta for a polymer. (c) Victoria and Albert Museum, London.

This is the analysis mostly used when dealing with plastics. The department has an especially nice FTIR machine – I say nice because it has a microscope attached to it (more on that in a later post…). I am also lucky because the department has the facility for Raman spectroscopy, which is a bit like FTIR, but isn’t as widely used in conservation – mainly due to the historic high cost of the machine, but it’s thankfully coming down.

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The Raman machine. (c) Victoria and Albert Museum, London.

Over the year I will also be helping out with some of the other people in the Conservation Science department. Ill will get a chance to see how the Pest Management systems works and how we keep track of the environment we store the objects in. This is a great opportunity for me to learn as much as I can about the conservation of plastics and about large museums, so if some day you see a post about moths or the UV levels in a gallery, don’t worry you haven’t ended up at the wrong interns blog!

And lastly… It’s not all high tech here at the Victoria and Albert! Sometimes the simplest method is the best, and nowhere is that better demonstrated than in the way objects are carried, short distances, internally within the museum.

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The little baskets that objects come to the lab in – the simplest and safest way for them to travel short distances! (c) Victoria and Albert Museum, London.