Stone Conservation

Stone conservation at the Bergen Museum

This month two of our team, Zina and Marielle were leant out from the whale project for three weeks to help clean and restore a beautiful stone sculpture of the goddess Athena. She is the goddess of wisdom and adorns the front of the museum and her attribute, the owl, can be seen in the Bergen University’s seal.

The sculpture on the museums façade is composed of Athena in the centre, measuring 1280 x 700 x 2050 mm (length x depth x hight) flanked by two smaller rocaille volute ornaments. The stone ornaments have been carved in German sandstone possibly Obernhofern sandstone which is also known as Bremer stone.

A drawing of the Athena sculpture and stone carvings on the front of Bergen Musuem.

Over the years, since it was created in 1865, the sculpture has been badly affected by the pollution in Bergen and a black crust has formed over the stone. In addition the sculpture has other problems such as flaking stone which has been caused by running water, frost and salt damage. A stone conservator from Stavanger Museum came to assess the work and make an initial treatment proposal and then Zina and Marielle began work on restoring this beautiful and symbolic feature of Bergen University .

The first week up on the scaffolding the temperature held a steady minus ten degrees and we were very grateful when woolly socks were bought in and an extra heater was put up! We started with testing the recommended cleaning method which was first soaking the surface with water and then cleaning with soft metal brushes and more water. Since the black dirt was tougher then anticipated, we developed a method of packing them in over night with wet cloths (to keep them wet as long as possible before cleaning) as well as applying a triammoniumcitrate gel on very black areas. This complex binder loosened the black dirt a bit and saved our arms from scrubbing too much!

Pictures of part of the Athena Sculpture before and after cleaning.

Over the three weeks we carried out this method and with a lot of scrubbing we were happy with the result in the end. By doing repairs with a sandstone mortar on flaking surfaces the stone will be protected from further damage caused by rain and frost. We have enjoyed undertaking some stone conservation work but we’re also looking forward to being back in the (relative) warmth of the whale hall!

So, for now it’s time for Christmas holidays and celebrations and work on the whales will begin again in January 2011. From everyone in the whale team we wish you a very Happy Christmas and New Year.

A Very Delicate Skull

Things are moving along quickly and we have almost completed cleaning the Sei whale skeleton.

However, the skull on this skeleton requires a lot of careful and painstaking work. The cranial bone has deteriorated considerably is now extremely thin and delicate. In addition there is a lot of exposed trabecular bone (the honeycomb like bone found beneath the smooth surface bone). This makes cleaning the bone very difficult as we do not want to damage it any further.
This picture shows how paper thin some of the bone on the skull is.





There is evidence of past repairs to the skull as there are thin strips of bone, that appear to have fallen off, screwed back onto the premaxilla, often with small wooden supports added. We have also discovered fragments of bone lying in the skull which have fallen off the maxilla, vomer and nasal bones.

Gordon has been tackling the skull and has modified our usual cleaning methods to work in this area. In order to clean the very thin bone he applied a solution of ammonia with a soft brush to the bone surface, left it for 5 minutes and then using the soft bristled brush gently foamed the solution on the surface, lifting the dirt. This was then removed either with a vacuum cleaned or with tissue paper to blot off the excess, so that no rubbing or scrubbing was required.

The parts of the pre-maxilla that had previously been screwed back on were removed and carefully stored so that they can be re-attached more sympathetically later on in the project. All the small fragments we found were glued back into place (a bit like doing a whale skull jigsaw puzzle). This was achieved using a special conservation 'glue'called paraloid (acryloid) B-72. The important thing about paraloid is that it is 'reversible' - that is, it can easily be removed in the future using acetone. The use of non permanent 'glues' is an important aspect of conservation as it means you can repair a specimen with the possibility of non destructive change if necessary in the future.

The paraloid was used in combination with Japanese tissue paper to stick the paper thin bones together. The tissue paper was used as a reinforcing agents as the edges of the bones were just too thin to stick to each other.

Here are some pictures of the Sei whale as it is being cleaned....

The Sei whale skull work is nearly completed and the team are moving onto the Humpback whale - once again we have found a name - Roger!

Forskningsdagene

It was a very busy Sunday for Bergen University as it hosted a Research Day (Forskningsdag) for the public. There was a busy schedule of events - from mummifying a hen to getting oil from a stone. The whale project was included and people could come and visit us here in the Whale Hall, climb the scaffolding and get up close and personal with the whale skeletons.

Despite the very stormy weather we had around 100 visitors in just 3 hours so the whale team was very busy showing people around and answering questions! We hope everyone enjoyed seeing the skeletons and the Museum project in action.

Laser Cleaning

Laser Cleaning

Whilst experimenting with cleaning methods we gave laser cleaning a go.

Laser cleaning is becoming increasingly popular in conservation, particularly when dirt needs to be cleaned from very delicate surfaces such as textiles and paintings. The most commonly used laser cleaning systems in conservation emit short pulses of light, typically at a wavelength of 1064 nm or 532 nm. Light at this wavelength quickly and selectively heat the dirt on the surface, which expands and comes away.

In many cases, the light interacts only weakly with the surface of the object and the removal process stops as soon as the clean surface is exposed due to colour differences between the dirt and the surface. It is, therefore, possible to completely remove unwanted layers without over cleaning the valuable surface. This type of cleaning could be very useful for areas of bone that are very fragile and a method that did not ‘touch’ the surface and cause further damage would be advantageous – such as the underside of some skulls which has begun to peer away.

Although this cleaning method is often used on stonework and paintings there is very little research about it’s effect on bone – so we proceeded with caution and started our tests on some objects that had been up in the attic and were not of scientific importance. We chose items that would be very difficult to clean with traditional methods and so would be good subjects for laser cleaning. We had mixed results – in some cases it was very effective and removed dirt from surfaces that would otherwise have been awkward to clean. However, occasionally the laser failed to remove much dirt, or caused a change in colour of the original surface.

This may have been because lasers do not work on dark materials with lighter dirt cover - only the other way around! That's why lasers are often great for cleaning light \ greyish sandstone and marble with a black crust and that's exactly why we thought it could work on our bone material. Small tests have shown that dirty bone surfaces (without oil!) are easily and effectively cleaned with lasers.

Examples of laser cleaning: Swan feathers; the spikey skin of a flat fish; coral

As you can see the laser removed the dirt from the feathers but also discoloured them - making them yellow. The flat fish and coral however were successfully cleaned.

We then tried the laser on the stable surface of jaw of ‘Finn’, the Sei whale’s. The results however were not all we had hoped for. The laser did not damage the bone or change it’s colour which was positive but nor did it remove much of the dirt!

Laser cleaning the mandible of the Sei whale

It wasn’t as effective as using ammonia or a water and detergent. So, although we had fun experimenting with the laser cleaner and managed to clean some usual objects that otherwise would have remained dirty it wasn’t going to be a useful tool for the whales.

A square of oily whale bone after laser cleaning. Although some material has been removed dirt and grease remains on the surface.

We've been making great progress in the whale hall and we've finished cleaning Benny the right whale!

It's been a great leraning process cleaning our first whale as we've had the oppertunity to experiment with different techniques. We've constantly modified cleaning solutions and tools to work out what works best on the many different bones. In some places thick black oil needed tackling and in others deeply ingrained dust in fragile exposed trabecular boned needed removing. We've experimented with everything from sand-blasting equipment and laser cleaning to potato powder, soapy water and solvents. The tooth brush and sponge have become our tools of choice and we have now refined the techniques to effectively remove dirt from both robust and fragile bone.

We can't believe the difference claening has made to the skeleton - it looks great!

The next step is to start cleaning the Sei whale - named Fin. We will begin by vacuuming off the loose dust and then start wet cleaning. For very oily parts of the skeleton we use ammonia to degrease but for non oily areas we use detergent in water, rinsed with alcohol to remove any remaining surface water or residue. It's not a fast process but using tooth brushes to reach into small areas and sponges for larger areas is providing an effective yet gentle method

An Exciting Visitor!

It's been a very exciting week for the Whale Team as we've had a rather exciting visitor - the poet Kathleen Jamie.


Kathleen published her first book of poetry when she was just 20 years old and has gone on to win many prestigious awards for her extensive work including the Forward Prize for her book The Tree House which focused around nature and the natural world. Kathleen has long been involved and interested in nature and wild environments and she has developed a particular interest in whales and our attitudes towards them ever since watching Minke and killer whales on the shores of her native Scotland and finding a whale vertebrae washed up on the beach. An interest in bones (and whales) is the inspiration for her new book - a collection of essays - and she has visited us here at Bergen Museum to explore the project and the skeletons we are working with as research of one of the essays.


So, for the last two days Kathleen has been in the whale hall observing and exploring the skeletons and the work we are doing. It's been really interesting and fun working with Kathleen and I think we've gained a lot from the experience of talking with her and spending two days in her company. Although Kathleen has seen many whales in the wild both from the shore and from boats she is not as familiar with their skeletons - this visit gave her the opportunity to spend some time getting to know the bones and their history. She also inspired us to organise a trip to go and see some whales in the wild, as, despite spending all day working with whale skeletons not one of us had actually seen live whale in it's natural environment! So, we plan to have a whale team jolly to the North of Norway this autumn where we can see the Orca migrating along the coast following the herring the eat. We can't wait!

We hope Kathleen enjoyed visiting the whales here at the Museum as much as we enjoyed meeting her and we really hope she can visit again next year to see how the work is progressing - we look forward to her book being published and reading her new and exciting work.

The Cleaning Begins

Looking out from the scaffolding over so many huge bones in need of intensive cleaning, conservation and restoration certainly seems like a monsterous task but we have to start somewhere so we have chosen to begin working on the whale hall's most famous skeleton the Right whale (Ubalaena glacialis) which has been hanging in the musuem window for the city to see for around 100 years.





We've named the skeleton 'Benny' and the cleaning has begun.




This first skeleton gives us the oppertunity to develop the techniques we will use for cleaning this fragile and very unique bone material. The skeletons continually ooze a thin layer of oil - this oil comes from the thick layer of blubber produced by the whales in life - and the dust and dirt sticks to this oily layer forming a tough and greasy black layer over the bones.




An example of the grease and dirt layers in this case covering tail vertebrae.

Marielle cleaning Benny's arm

After experimenting with various cleaning solutions and recipes we settled on using substances that would have a degreasing effect and remove the vast amjority of the dirt without ....... the excessive use of water (which can be absorbed by the bones), without damaging the structure of the bone (bleach for example would dregrade DNA) and that wouldn't leave any surfacantants on the bone surface.

Finally, it was decided that after much experimentation a combination of ammonia hydroxide, ethanol, acetone and detergent would be used. This has proved very effective as the photo of Benny's arm below shows....

A dramatic difference can be seen in the bone colour between the cleaned ulna (top) and uncleaned radius (bottom).

However, despite the fact that the whale oil is causing so many problems for our skeletons (and the team trying to clean it off) traditionally it has been a hugely important and widely traded product that was harvested particularyly from Right whales such as Benny. Whale oil has been used in a wide range of products from lipstick to margarine and it wasn't until the descovery of petroleum waxes and oils that it went out of use.

The scaffolding is up!

Once the sharks in the whale hall had been moved out or protectively wrapped the scaffolders could start work and in less than a week one half of the whale hall was covered with a network of scaffolding paltforms postioned around the hanging skeltons that we could access by steps and ladders.

The scaffolding goes up around the protectively wrapped basking shark specimen

The floor of the whale hall is original, dating back to the 1800's so it cannot be heavily loaded as we don't want to risk damaging it. For this reason we made the decision that rather than putting scaffolding up in the whole hall we would scaffold half the hall and work on the skeletons hanging in that area and then dismantle and move the scaffolding to the second half of the hall and work on the remaining skeletons.


The floor and glass cabinets surrounding the walls of the hall are covered to protect them from debris and dust.


It's an exciting time as now we can get up close to the skeletons for the first time and really see what condition the bones are in and what work needs to be done to conserve them...........


The scaffolding will allow us to quite literally work in the belly of the whales!

Four stuffed sharks and a sunfish

The huge sunfish hanging in the whale hall

Back in March this year Catherine, Zina, Marielle and Gordon had arrived in Bergen and together with Christina and the others at Bergen Musuem the whale team was all finally together. We quickly got to know each other over many cups of coffee and pieces of cake and started to plan the work that would need to be carried on the whale skeletons.

So, first things first, we needed to reach the skeletons hanging high up above the musuem floor.

It was quickly decided that scaffolding and platforms should set up around the skeletons at almost ceiling height giving us access to every part of the whale skeletons. However as well as the whale skeletons the whale hall contains two whale skulls, one of a Bottlenosed whale and one of a sperm whale and some very unique examples of large, stuffed shark skins and a huge stuffed sunfish. Before there would be room to put the scaffolding up around the whale skeletons these would first have to be moved.

The sharks in the whale hall positioned under the hanging whale skeletons.

These skins are very interesting as they are examples of musuem taxidermy that is now very rarely seen. Today it is much more common to make casts and models of large marine animals as this method of preserving and stuffing skins is much more difficult. Because of their age they are very fragile and it was important that they were not damaged in the moving process.

The 'stuffed' basking shark skin - a beautiful example of a rare taxidermy technique

We set about gathering together all the fit young (and some not so young) men and women we could find wandering the corridors of the musuem offices. Then, after much padding, wrapping and cushioning and a lot of help and some very useful ideas from Umberto and Thor we lifted and moved 3 of the sharks and the bottlenosed whale skull out of the hall. Together with their stands they were unbelievably heavy!

The sunfish,basking whale and sperm whale skull were just too big and fragile to risk moving so they were carefully wrapped by Marielle ready for the arrival of the scaffolders.....

The now clear floor of the whale hall ready for the scaffolding to be put up.

Meet The Whale Team

Hi, it's nice to meet you.....

The whale team are the group of people planning, organising, undertaking and running the whale project. We all have different roles within the team and together we will conservate and restore the whale skeletons over the next 2 years.

We come from Norway, Sweden, Denmark and the UK and have a wide range of skills and experience which will be very useful as we tackle the often complicated problems presented by this chanlenging work.

Terje Lislevand: Associate Professor in zoology at Bergen Musuem. Terje is the leader of the whale project and responsible for the musuem's animal exhibitions.

Marie Louise Lorentzen: A painting conservator from Stockholm, she gained her bachelor degree in paintings and polychrome sculpure from The University of Gothenburg. For the last nine years Marie Louise has worked for the Culture History Collections at Bergen Musuem and since 2009 has been an advisor within the Musuem Project 2014.

Christina Holmefjord: Gained her bachelor degree in archaeology before qualifying as a natural history conservator at The School of Conservation, Copenhagen. Christina has worked as a conservator at Bergen Musuem for many years and together with Andreas Grinde wrote a detailed condition report on the whale skeletons.

Gordon Turner Walker: An archaeological conservator from the UK. Gordon gained his PhD at Durham University and for the last 7 years has worked in The Graduate School of Cultural Heritage Conservation, National Yunlin University of Science and Technology.

Marielle Bergh: Is a cultural historic conservator from Gothenburg University, Sweden with a big interset in natural history museum conservation.

Zina Fihl: Is a natural historic conservator from Denmark who qualified at The School of Conservation , Copenhagen. She has a special interest in casting and palaeontology.

Catherine Hellier: Is an anatomist from the UK. Catherine gained her PhD at The University of Liverpool and has since been working at The Gades Institute and Department of Anatomy, The University of Bergen.


You will hearing a lot more about us and getting to know us a lot better as the project continues ....

Hello and welcome to The Whale Bone Blog!

This blog will follow the progress of a team of people who, over the next two years will conserve and restore the eight largest whale skeletons in Bergen Museum's historic Whale Hall.

The restoration of the whale skeletons is part of the exciting Museum Project 2014 currently being undertaken by The University of Bergen, Norway.

We hope that you will enjoy following our progress as we work to restore this beautiful and unique skeletal collection for future generations of visitors and scientists।


Bergen Natural History Musuem where the whale skeletons are housed.


Whale skeletons hanging in the historic whale hall.


The Whale Bone Project

All eight of the large whale skeletons hanging in Bergen Museum's Whale Hall have been there for over 100 years and over this time have collected a huge amount of dust and dirt. In addition whale skeletons contain a lot of oil and this comes to the surface of the bones forming a greasy layer which the dust and dirt gets well and truly stuck to. There are also 100 years of paint splashes, old repairs and of course, disintegration of the skeletons to contend with. All in all the skeletons are in need of some serious care and attention to clean, repair and stabilise them and this must all be achieved with methods that do not harm the old and often delicate bone. The reason for conserving these skeletons is not simply so that they look better but it is to prevent the continued disintegration of the bone and halt the damage the dirt is causing so that the skeletons stay intact and exhibited in the hall for years to come.

It's going to be a challenge but fortunately the team have a range of skills and experience to carry out this whale sized task!

The Whale Skeletons

The whale team will clean and restore the eight whale skeletons that are most in need of urgent conservation. The skeletons are all baleen whale species and are comprised of one Blue whale (Balaenoptera musculus), one Sei whale (Balaenoptera boreali), one Humpback whale (Megaptera novaenglia) two Fin whales (Balaenoptera physalus), two Minke whales (Balaenoptera acustorostrata) and one Right whale (Eubalaena glacialis).
An illustration of a Minke whale - two skeletons of this species can be found in the whale hall collection.

The Blue whale is the largest skeleton in the Whale Hall at 24m long and it originally came to the museum from the Finnmark coast in 1879. The 13.2m long skeleton of the Sei whale and the skeleton of the Humpback whale which measures in at 13.5m long, were also collected off the Finnmark coast in 1879. The two Fin whale skeletons, the longest of which is 18.9m, were collected off Utsira in Rogaland in 1865. The two skeletons of Minke whales in the hall were collected off Skogsvåg on the island of Sotra, just by Bergen in 1860 and finally, the whale skeleton hanging in the main window of the Whale Hall is the 16m Right whale collected from Iceland in 891.


An illustration of a Right or Nordkapper whale, a skeleton of this species has been hanging in the main window of the whale hall for over 100 years.

A Short History of Bergen Museum and the Whale Hall

The Bergen Museum was founded in 1825 and forms part of the University of Bergen. it houses one of the largest collections of cultural and natural history objects in Norway. Today there are 22 complete mounted whale and dolphin skeletons and two whale skulls in The Natural History Museum's grand Whale Hall, representing a total of 18 species. This unique collection is of special scientific interest as it represents a diversity of species which are irreplaceable today. The skeletons have quite literally been the museum's public face for well over 100 years, as they hang in the Museum's large central window overlooking Museplass for everyone to see.

Most of the whale skeletons which today hang in the Whale Hall were probably in place right from the first year the museum was open. It is interesting to see the photos ca. 1895 which show the skeletons hanging from the ceiling in the Whale Hall and the exhibition is very similar to how it remains today.

The image above shows how the Whale Hall looks today ......and the image below shows it in 1895
The museum's early interest in whales can be found in both scientific and popular articles such as the Bergen Museum's Annual Yearbook Report and the Journal Nature (Guldberg and Nansen 1894; Grieg 1889, 1897, 1905).

By preserving the skeletons we are also preserving part of the museum's identity and history.