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A hand holding a a wide brush is cleaning a the skeleton of a whale, brushing a thick layer of dust towards the nozzle of a hoover.

The whale specimens need to be cleaned on a regular basis as dust can eventually damage the bones. 

Whale oil and half an inch of dust: our bowhead whale gets a clean

Author:
By Josh Davis

As the whale hall at the Natural History Museum undergoes a deep clean and refresh, we take a peek behind the scenes at how our conservators have been cleaning one of the biggest specimens on display: a bowhead whale skeleton. 

The last time the whale skeletons hanging from the ceiling of our whale hall were cleaned was 16 years ago.

Closing one of our most popular galleries and building enough scaffolding to reach the ceiling is a huge challenge, and meant that these suspended specimens were long overdue a deep clean. So as the gallery was closed for a refresh, the conservation team tasked with keeping all the specimens on display in top condition jumped into action.

They have spent six weeks scrambling up and down the scaffolding that has filled the vast space to spruce up the four whale skeletons on display.

These include the immense remains of a bowhead whale that was collected off the coast of Greenland between 1881 and 1882. The skeleton measures a whopping 14 metres long and has been in the collections since 1934.

The bowjead whale specimen surrounded by scaffolding and boards, as one person in a hi-vis jacket is cleaning the bones.

The bowhead whale skeleton on display was collected off the coast of Greenland 160 years ago, and has been at the Natural History Museum since 1934.

Two layers of dust

There was a half inch-thick layer of dust over the entire surface of the bowhead whale that could effectively be peeled off in one go. But as Arianna Bernucci, one of our senior conservators goes on to explains, a little more goes into the care of these specimens.

‘All of the whales get what we call a dry cleaning and conservation,’ explains Ari. ‘So hoovering to remove that really thick layer of dust, and then normally we would also sponge the specimens with a dry sponge.’

‘But because the dust was so thick this time, they actually required more cleaning. There was literally two layers of dust. A soft, fluffy upper layer, and then as that was depositing it was compacting a second layer underneath.’

A close up of a large, fuzzy lump of grey dust on the surface of the whale bone.

Due to logistical problems in accessing the whale specimens, it had been 16 years since they were last cleaned. 

A purple gloved hand peeling back the top layer of dust, which is coming away in a single piece like a sheet of fuzzy felt.

The dust had formed two layers, of which the soft, fluffy upper layer could be peeled off as if it were a layer of felt.  

This required the team to do an initial pass with the hoover to remove the thicker top layer of dust, and then a second pass to suck up that finer layer beneath.

It is important that these specimens are cleaned and looked after because dust is hydroscopic, meaning that it acts like a sponge and draws in water that can damage the bones underneath. Pests can also colonise the dust and start to call it home, as some organisms will feed off the dust itself.

Getting up close with the whales has also allowed Ari and her colleagues to assess the skeletons for any potentially dangerous cracks or deterioration in the bones.

But one of the main issues with marine mammal specimens , such as whales and dolphins, is a little stickier.

Their bones contain a lot of oil. In life this substance is critical for the animals to maintain buoyancy in water and was the reason why so many were slaughtered during the eighteenth and nineteenth centuries. But it can cause major issues when trying to preserve their remains in collections.

The view from inside the ribcage of the bowhead whale.

The cleaning also allows the conservation team to get up close to the specimens and check for any potential damage to the skeletons. 

A close up of a bone showing a wet, glistening pacth that is fresh whale oil.

Despite being collected 160 years ago, the bones of the bowhead whale are still leaching oil. 

Typically, when a fresh whale specimen is collected, preparators will attempt to remove as much of this oil as possible. But even then, they cannot get all of it out of the bones. The bowhead whale on display in the whale hall is still leaking oil 160 years after it was collected.

‘It's a very slow leach - so it's not pouring out - but you can see where it has slowly dripped out, almost like resin from a tree,’ explains Ari. ‘The bowhead and the right whale both had oily areas that were super sticky and we felt like it was going to keep attracting dust and actually cause a potential issue for the specimens.’

‘We made a decision to use ethanol to just gently reduce it, in a process of swabbing the area and then letting it dry and then if it still feels sticky to the touch then you would do a little bit more.’

Two people wearing hi-vis jackets and masks burshing and hoovering the skull of the bowhead whale on either side of the skeleton.

The refresh of the whale hall will make it easier for the conservators to clean the whale specimens at least once a year from now on. 

Life within the dust

A close up picture of brush with fluffy grey dust hanging off it.

Most of the dust is incinerated, but a small sample is saved so that it can be analysed to see what is living it. 

Inevitably, the process of cleaning four whale skeletons produced a lot of dust. All of it had to be collected and disposed of as hazardous waste, but not before a few samples were collected. Some of these were sent to be tested to see what, exactly, might be growing on and within the dust.

This isn’t the first time that the team have done this. When Hope the blue whale was moved to Hintze Hall in 2017, the skeleton also underwent a deep clean. The dust from Hope was analysed to reveal a whole community of fungi and yeast living within it and on the whale’s bones too. They found species of Penicillin as well as yeasts that have also been found in alpine glaciers and sediment from north Siberia.

Similar analysis will be conducted on this new dust. A few additional samples have been packaged away and added to the collection.

‘We save a portion of it for research and analysis,’ says Ari. ‘We still actually have dust from Hope [the whale] that we saved just in case, because you never know when a new analytical technique is going to come.’

‘So watch this space to see what we can find.’

With the new refresh of the gallery cleaning these specimens will be made easier, allowing Ari and her colleagues to access them at least once a year from now on.  

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