{"id":1376,"date":"2020-01-04T14:20:22","date_gmt":"2020-01-04T14:20:22","guid":{"rendered":"http:\/\/blogs.cardiff.ac.uk\/conservation\/?p=1376"},"modified":"2020-01-04T14:36:23","modified_gmt":"2020-01-04T14:36:23","slug":"uv-huh-what-is-it-good-for","status":"publish","type":"post","link":"https:\/\/blogs.cardiff.ac.uk\/conservation\/uv-huh-what-is-it-good-for\/","title":{"rendered":"UV Huh! What is it good for?"},"content":{"rendered":"\n

Ultra-violet (UV) light. What\u2019s the first thing that springs\nto mind when you think about it? Those blacklights used in forensic crime\ndramas to reveal hidden clues? That episode of Friends with Ross and his blindingly\nwhitened teeth? Or perhaps you\u2019ve heard conservation horror stories about the\ndangers of UV light and how damaging it can be for objects. As conservators\nhowever, UV light is not just something we need to protect objects against, but\ncan actually use as a tool for learning more about them. So, how does it work\nand what can we use it for? <\/p>\n\n\n\n

The\nreason some materials glow under UV light is down to how the electrons in these\nmaterials absorb the invisible UV radiation. The electrons absorb this energy, which\nexcites them to higher energy levels. As the excited electrons slowly return to\ntheir lower energy levels, a bit of the energy they absorbed is given back out\nas visible light, which we see as a glow or \u201cfluorescence\u201d (Hosch, 2009). The\nway that these electrons react to the UV light determines the colour and\nstrength of visible light that these materials emit. <\/p>\n\n\n\n

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1. Electromagnetic spectrum. Source: Hubblesite.org<\/figcaption><\/figure><\/div>\n\n\n\n

Conservators can use UV light for a number of different purposes.\nSometimes it\u2019s used to identify materials by the distinct colours they\nfluoresce. Other times it can reveal hidden aspects of the objects themselves;\nshowing up evidence of previous repairs or changes, or sometimes even fakes!<\/p>\n\n\n\n

 Fluorescence (or the\nlack of it) in an object can reveal important information that conservators can\nuse to better understand their objects. Because different materials will react\nto UV light in different ways, there is a wide variety in the types of fluorescence\nwe might see. Thankfully, there are some helpful online tools for interpreting\nwhat the various types of fluorescence actually mean. A particularly good one\nis the Australian Institute for the Conservation of Cultural Materials\u2019 guide\nto UV fluorescence, which can be found here (https:\/\/aiccm.org.au\/national-news\/summary-ultra-violet-fluorescent-materials-relevant-conservation<\/a>).<\/p>\n\n\n\n

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2. Full view of current state of the Egyptian ceramic bowl. Source: Author <\/figcaption><\/figure><\/div>\n\n\n\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nIn my case, I ended up deciding to use UV light\non my very first object \u2013 a large Ancient Egyptian ceramic bowl that had been\nsent from the Swansea Egypt Centre to Cardiff University for treatment (if\nyou\u2019re interested in learning more about what the Egypt Centre gets up to, give\ntheir blog at www.egyptcentrecollectionblog.blogspot.com<\/a>\na visit).\n\n\n\n<\/p>\n\n\n\n

The bowl was in a bit of a sorry state by the time I got it. At some point in its past, it had been broken quite badly and someone had previously tried to stick the pieces back together. Unfortunately, the adhesive they used has aged badly and the bowl is now falling apart again. As no one at the Egypt Centre knew what had been used to repair it, before I could even think about what treatment I was going to do first I had to find out what the adhesive was.<\/p>\n\n\n\n

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3. UV light set-up at Cardiff University. Source: Author<\/figcaption><\/figure><\/div>\n\n\n\n

After some research, I had a couple of theories about this,\nbut I didn\u2019t know anything for sure. So I decided to try UV light and see if it\ncould narrow down some of my options. <\/p>\n\n\n\n

I used the main set-up that we have at the Cardiff\nUniversity conservation department, which consists of two UV lamps in the photography\ndark room in room 2.25, with a camera rig set up to take photographs. Actually\nusing the UV light set-up is pretty easy \u2013 switch off the lights, turn the UV\nlamps on and see if anything glows. You do need to wear UV filtering goggles\nwhile using it though \u2013 this kind of UV light can be really damaging to your\neyes (Measday, 2017)!<\/p>\n\n\n\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nTo be honest, the main challenge for me here\nwasn\u2019t using the UV lamps themselves, but really just trying to take photos in\nthe dark! It took me a while to get the hang of finding the right buttons on a\ncamera in the dark, and my first couple of attempts involved a lot of fumbling\naround and some less than polite words directed towards the camera. I did get\nthe hang of it eventually though \u2013 perseverance is key! \n\n\n\n<\/p>\n\n\n\n

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4. Base of bowl under normal and UV light. Source: Author<\/figcaption><\/figure><\/div>\n\n\n\n

The photography I took of my object under UV light ended up being very revealing. Not only did it narrow down the kind of adhesive I was looking at and highlight how much of it was on the surface of the bowl (and oh boy was there a lot!), but it also showed me something unexpected \u2013a second adhesive alongside the first (a deep blue fluorescence, separate from the main adhesive which showed up as a white-ish yellow). <\/p>\n\n\n\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nI have to say, I was thrown for a bit. Under\nnormal light all the adhesive had looked the same to me. Finding another one was\nsurprising! It goes to show exactly why doing tests like these are important.\nYou may find that they can reveal unexpected things that can hugely impact how\nyou approach treating your objects. Now I need to factor in a second (currently\nunknown) adhesive into my future treatment plans. Without doing a UV test\nthough, I may never have even known to look for it in the first place!\n\n\n\n<\/p>\n\n\n\n

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If, like me, you think it may be worth looking at your\nobjects under UV light, here are a couple of pros and cons about this test\nmethod.<\/p>\n\n\n\n

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PROS<\/span><\/p>\n\n\n\n