The recent research visit to examine the Abingdon Ichthyosaur presented an excellent opportunity for the Collections Officer to give the fossil some TLC. The display case is rarely opened, but even when shut, it is not completely sealed. The glass top is in three sections, and the joints between them are not sealed, so over the years dust and dirt has fallen through the gaps into the case below. Particularly visible were the rubbery crumbs from erasers, as multiple school classes have rested their clipboards on the case top, writing and drawing.
Nobody likes dust in museums – it is not only unsightly, but it can also do damage.
But what exactly is dust? In this case, the eraser crumbs are the most obvious component, but dust is made up of other constituents as well. The most general definition of dust is “fine particles of solid matter”. There are skin cells and clothing fibres shed by visitors, and paper fibres spread from the office. Dust also comes in from the outside: pollution from passing traffic, pollen, soil particles. Heavy traffic – or the annual fair! – can make the building vibrate and shake dust loose from the walls and ceilings.
Why is dust bad for museum objects? Dust can attract small insects who see it as food – and will also eat the objects if they get a chance. Even if they don’t, they could attract other, bigger creatures who eat the smaller ones, and they can do damage with their droppings. Spiders are notorious for this. Perhaps you have seen this in your own home. I certainly have – I recently pulled a long neglected box from a shelf only to find the tell-tale grey spots of spider poo all over it.
Dust also attracts and captures humidity, which can lead to mould growth, or cause rust on metal objects. And if you leave the dust on the objects for too long, it can become ingrained or form a more cemented layer on top. Museum objects can’t be scrubbed like the top of your fridge at home, so once the dust has become compacted, it is much more difficult to remove.
All excellent reasons therefore to keep on top of the dust in the museum.
Apart from the bits of dirt, though, the Ichthyosaur is well protected in its case. It rests on a layer of Plastazote, a thin foam which is widely used in museums. The case is sturdy and stable, and the glass is thick enough not to break or crack, so the bones are protected from pretty much everything except those little aforementioned bits of dirt.
Now, taking the sections of the glass top off one by one, I set about cleaning up the interior of the case.
The main tools I used for cleaning were a brush and a vacuum cleaner. The brushes I use in the museum are any sort of soft brush. Here I have used a paint brush (which has obviously never been used for painting!), but if something even softer is needed, I use a make-up brush. I used the brush to move any bits of dirt away from the bones. This sometimes necessitated moving the bones as well, but since they are all numbered, I wouldn’t lose sight of how they fit together and could move them back where they belong.
Once the dirt was moved away from the bones, I could use a vacuum cleaner to remove it completely.
Here it was necessary to use specialised equipment and not the same vacuum cleaner we use for the museum floors. I used a Museum Vac, a small, portable vacuum cleaner specifically made for museum use. These have adjustable suction levels which can be turned down very low, to prevent bits of fragile objects from disappearing into the hose. They are also small and light, so they can be lifted and carried around easily. This makes it possible to use them for example while standing on a footstool or up a ladder.
And that’s it. Next time you see the Ichthyosaur, it will be in its newly spruced up environment, free from dust and dirt as it should be.
Elin Bornemann, Collections Officer