This spooky-looking picture shows the silver ship model of the Terra Nova as it appears under ultraviolet (UV) light. Fiona Cahill started conservation treatment on the model when it was given to us in 2010, and I have taken up the project where she left off.  One of the first things I did was to examine the model under UV.  UV light examination is a very useful technique for spotting old conservation repairs, because often glues and coatings “fluoresce” and show up in various colours under UV light, where they can be hard to see in visible light.

The ship model was coated in lacquer a long time ago to prevent it from tarnishing, and now this needs to be removed because it has turned an ugly yellow with age.  Under UV light the lacquer looks pale green, while the areas where the lacquer has been cleaned off look purple.  Here it is clear which parts of the rigging are still lacquered and which are not:

The ship model is very intricate, and cleaning the lacquer off is a process that takes weeks, so the UV lamp is brilliant for showing up areas which have been missed, or which need more cleaning.

The lamp is also useful for spotting repairs that are not very obvious in normal light.  This is a soapstone sculpture of a musk ox by Henry Evaluardjuk, a famous Inuit artist.  Under normal light it looks OK.

But under UV light you can easily spot smears of adhesive on the surface – and then remove them.

In some cases the colour of the UV fluorescence is very distinctive and can help identify the adhesive or coating.  Knowing which resins have been used on objects in the past makes all the difference when deciding how to treat them in the present.

The UV lamp is actually just a normal task light with UV fluorescent bulbs installed in it (and thank you to the Fitzwilliam Museum for lending these).

The bulbs give out high frequency UVA rays which are pretty hazardous.  This means that I have to cover my hands and skin to protect them when using the lamp, and I also have to wear a fetching visor to protect my eyes (no, it is not a welding mask!).

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