MV Blog

DISPLAYING POSTS TAGGED: conservation (9)

Cork Colosseum x-ray

Author
by Kate C
Publish date
17 April 2014
Comments
Comments (0)

An x-ray machine usually employed for mammography examined an unconventional patient earlier this year: a model of the Colosseum made from cork around 1800. Thanks to generous assistance from Lake Imaging in North Melbourne, object conservator Sarah Babister now has a view inside one of our most curious objects.

Four people discuss photograph Conservators Sarah and Dani show radiographers Jeff and Ghazia a photo of the Colosseum model.
Source: Museum Victoria

cork Colosseum model The facade of the Colosseum model. (HT 24386)
Source: Museum Victoria
 

Radiographer Ghazia adjusted the settings of the mammography machine to accomodate this unusual material—cork is much less dense than human tissue—and produced wonderfully clear and informative images of several pieces of the Colosseum.

Woman with x-ray machine Ghazia placing a piece of the Colosseum on the mammography machine.
Source: Museum Victoria

Woman with computer Ghazia adjusting the levels of the x-ray to best show the hidden structure within the cork Colosseum.
Source: Museum Victoria
 

We think that our Colosseum was built by English model-maker Richard Du Bourg (or Dubourg), but in the absence of a signature, Sarah is looking for characteristic materials and construction techniques that could confirm its maker. Further research by historian (and the museum’s Head of Humanities) Richard Gillespie and genealogist Neil Gill is fleshing out the intriguing story of Du Bourg and his models; Richard recently visited similar objects in overseas collections for comparison. Sarah and Richard will present a talk about the model and its story next month as a part of the History, Cultures and Collections seminar series.

From 1775 to 1819, Du Bourg’s models of classical ruins were the height of fashion and his a well-known London exhibition. “He’s a fascinating character,” says Sarah. Notoriously, his working model of Vesuvius destroyed an entire exhibition when its eruption set fire to all the other models on display. “He lived until he was in his early 90s and even though he’d been very famous he was living in poverty.”

Sarah explains that cork models “were really popular at a certain time and were kept as tools to teach students. Then they fell out of fashion and a lot of them were disposed of.” This may explain Du Bourg’s impoverished old age, and is the reason why the museum has this model at all – in 1929 it was sent from the Science Museum in London to the Industrial and Technological Museum in Melbourne.

cork Colosseum detail Sarah holding a large piece of the Colosseum model.
Source: Museum Victoria
 

The model is over a metre wide and in poor condition. The base it sits on is cracked and the gesso applied to the perimeter is flaking, and several sections of wall have broken off. These broken sections are a mixed blessing, since without them there could be no x-rays, which reveal the lead pencil marking lines, and pins and nails used to hold the pieces of cork together. This information may help confirm whether Du Bourg made the model, but will also help Sarah reattach the broken pieces.

X-ray image of a piece of the cork Colosseum X-ray image of a piece of the cork Colosseum. The metal pins, and decorative carvings covered in lead paint, appear white.
Image: Lake Imaging
Source: Museum Victoria
 

“Most of the pieces are there so the model would be virtually complete with the exception of a few small columns which might need to be replicated,” she says. “I’d love to put it back together so it can be viewed how it should be viewed because it’s such an amazing object. The level of detail in the carving is wonderful, and cork lends itself so well to representing that ruinous state.”

To learn what the x-rays revealed, come along to Richard and Sarah's free seminar on 14 May, titled For the Nobility, Gentry & Curious in General: Richard Du Bourg’s Classical Exhibition, 1775-1819.

Links:

Cork Colosseum model on Collections Online

Rehydrating specimens

Author
by Kate C
Publish date
25 March 2014
Comments
Comments (1)

Recent workshops brought together natural sciences collection managers and conservators from far and wide to learn techniques for preserving wet specimens – those preserved in fluids like ethanol and formalin.

Fluid preservation workshops Fluid preservation workshops underway at Melbourne Museum's conservation lab.
Source: Museum Victoria
 

The workshops, hosted at Melbourne Museum, were supported by the Australian Institute for Conservation of Cultural Material (AICCM) and taught by UK natural history conservator Simon Moore. Dani Measday, MV's Natural Sciences Conservator, says "you can’t learn easily natural sciences conservation in Australia, so people are really jumping on the chance to build skills in that area." With participants from Canberra, Sydney, Brisbane and even New Zealand, it was also a rare opportunity to meet others working in the field. “Museum people love to talk shop," says Dani, who toured the visitors around MV's collection stores. "There was definitely a lot of discussion about what people were doing in their museums. It's great to build up a network of people you can call on when you get stuck.”

Over four days, the workshops addressed some of the major problems of wet collections, one of which is dehydration as the preserving fluid evaporates. “The ones that were really dehydrated tended to come out of jars with rubber gaskets in the lids, which can perish quite quickly," says Dani. "Or they can get twisted and end up with a really poor seal.” A highlight of the workshop was seeing dehydrated specimens returned to full size under Simon's guidance.

Workshop participants cleaning Workshop participants cleaning perished rubber gaskets from mammal specimens.
Source: Museum Victoria
 

During the workshop, Dani worked on a juvenile koala specimen affectionately nicknamed Drinky Bill. This koala was originally collected from French Island and came to the museum in 1957 via the Healesville Sanctuary. In the intervening years, poor Bill lost all of his alcohol and was a dry fist-sized husk rattling around an empty jar.

The process of rehydration, explains Dani, begins with placing the specimen in warm water with a surfactant. "It's basically a detergent to break down surface tension to help water penetrate into the specimen." The cells expand as they take in water, and the specimen returns to its original shape and weight over several hours.

 

Next, the specimen is re-fixed in formalin to stop the decay. Then it's back to ethanol in a series of baths of increasing strengths. "You need to move it through several different concentrations of ethanol gradually. If you go straight from water, it's a big change in pressure for the specimen." Dani's koala spent a few hours in each of 10, 30 and 60 per cent before the end point of 70 per cent. To remove any air bubbles and to make sure the koala was submerged, Dani used a vacuum chamber conveniently housed next door in the preparation department. "The preparators use it to remove bubbles when they’re casting in resin."

Koala specimen before (left) and after (right) rehydration treatment. Koala specimen before (left) and after (right) rehydration treatment.
Source: Museum Victoria
 

The resulting transformation is amazing. At the workshop's conclusion, some specimens in very poor condition were returned to near original state. Restoring the animal's natural size is particularly useful, as skins and skeletons can't tell us this information. It leads to some truly amazing applications; Senior Curator of Mammals Kevin Rowe says a researcher recently contacted him to find out the dimensions of a bandicoot. "He was designing radio tracking vests for bandicoots which don’t have necks suitable for collars. The best way to figure out the dimensions of a bandicoot is to look at a fluid specimen." This is because wet specimens "preserve internal soft tissue better than skins and skeletons. They also preserve the anatomical features of sperm, stomach contents, parasites–essentially everything in and on a specimen." 

Taxidermy conservation workshop

Author
by Kate C
Publish date
18 March 2014
Comments
Comments (2)

It’s clear that the old penguin specimen needs a lot of work. Age or accident has detached the bird’s head from its body, and preparator Steven Sparrey is carefully working PVA glue into the break in the neck. This will consolidate the edge and provide a sound surface for reattachment. Eventually, preened feathers will conceal the join and the penguin will be whole again.

Damaged taxidermied penguin Detail of damaged taxidermied penguin specimen.
Source: Museum Victoria
 

We’re at a workshop for people in the business of preserving natural history specimens – collection managers, preparators and conservators – led by visiting UK expert Simon Moore. The museum’s conservation laboratory is busy with people transforming elderly and damaged collection objects into exhibition-ready specimens, using specialist techniques that are very rarely taught in this country.

Taxidermy workshop Taxidermy conservation workshop in the conservation lab at Melbourne Museum.
Source: Museum Victoria
 

Sometimes the damage occurs from wear and tear, especially where specimens have done time in the museum’s interpretive collection. Other times it’s inadequate preparation at time of taxidermy – overstuffed specimens tend to split as the skin shrinks with age. Simon explains, “many of the specimens are decades old, and materials just become more brittle with time. “A small bump when handling can have drastic results on a fragile specimen, and the head is often the first to go.
We turn back to Steven’s penguin. “The skin on birds in particular is very thin and vulnerable to tearing,” says Simon. “In this case, the neck was overstuffed. As the skin dries out and retracts back onto the underlying material, it starts to split.” 

The penguin also needs a wing reattached, so Steven drills a fine hole for a galvanised steel rod to hold the wing on a natural angle. Next to him, Michael Pennell is finishing work on a mounted Regent Bowerbird, freshly reunited with its tail and perch. “He’s a little bit cleaner than he was this morning and I’ve filled a few little holes and splits.”

Man and bird specimen Preparator Michael Pennell working on a Regent Bowerbird mount.
Source: Museum Victoria
 

Elsewhere in the room, people are creating supporting armature for rabbit ears, cleaning feathers and mending tears in batwings with Japanese tissue. This tissue, says conservator Dani Measday, has unusually long fibres and resists tearing. “It means that it’s really strong and you can do all kinds of things with it. We use it to repair paper and books , but you can use it as fill, to strengthen and replicate fibres , or as a consolidating surface. What we’re doing with it here is making replacement skin. With adhesive, it has a tightness and tautness just like skin.”

repair to bat specimen Careful repairs to a bat specimen using Japanese tissue.
Source: Museum Victoria
 

Karen Roberts and Brendon Taylor are restoring tiny bat specimens. It's painstaking work; they have pinned out the fragile wing membranes and patched the holes with Japanese tissue. The purpose of the specimen dictates the treatment from here. “A scientific collection item can have warts and all, with minimal intervention,” says Simon. “Here we could put a gentle lacquer to hide the tissue, but obviously for display you’ve got to colour them in.” The extent of treatment for exhibition work can be deceptive, as the conservation treatments aim to draw the eye away from repairs so the specimen can be read as a whole.

Two men with penguin specimen L-R: Preparator Dean Smith with Simon Moore, looking at a damaged King Penguin mount.
Source: Museum Victoria
 

Simon’s own knowledge comes from decades of experimentation and consulting with natural history collections around the globe. “I’ve learned lots myself throughout the years and I’m trying to advance the technology, giving credit where it’s due. There aren’t many people doing taxidermy conservation and they keep trade secrets.” The techniques that Simon shares in workshops like this will help keep scientific and display specimens in good nick for study, research and exhibitions in years to come.

Consulting with Gupapuyngu community

Author
by Kate C
Publish date
17 October 2012
Comments
Comments (1)

Bark paintings present particular conservation challenges for museums and over many years, conservators have developed low-impact techniques to stabilise objects at risk of deterioration. However these objects often have deep cultural and spiritual significance to the people who created them, and any alteration to an object – including conservation treatments – may forever affect its meaning.

This issue has fascinated MV conservator Samantha Hamilton since her Mellon fellowship at the Smithsonian National Museum of the American Indian in 2005. For around two decades, NMAI conservators have worked closely with communities to better understand the cultural implications of preservation. "Involving traditional owners provides meaningful insights into the creation and appearance of cultural materials," says Sam. "This allows conservators to make clearer ethical treatment decisions."

Two significant bark paintings in the Donald Thomson Collection needed considerable conservation treatment, which meant they were not included in the travelling exhibition Ancestral Power and the Aesthetic. Given the long-standing relationship between senior curator Lindy Allen and the Arnhem Land communities from which anthropologist Donald Thomson collected the paintings, here was an opportunity to work closely with the cultural owners of the works. Sam and Lindy began consulting with direct relatives of the original artists last year and visited Milingimbi Island to discuss these particular conservation issues. This consultation project has received funding from the University of Melbourne and the Copland Foundation.

Two men with bark painting Artist George Milaybuma Gaykamangu and his brother Dr Joseph Neparrnga Gumbula holding a small bark painting made to show traditional painting techniques.
Image: Ben Healley
Source: Museum Victoria
 

During the first week of October, Gupapuyngu Elder and Indigenous scholar, Dr Joseph Neparrnga Gumbula and his brother, artist George Milaybuma Gaykamangu (Milay), came to Melbourne to exchange knowledge about how the paintings were made and how they should be preserved. In return Sam demonstrated various ways to consolidate paint and stabilise bark so that Joe and Milay could decide on appropriate treatments. Says Sam, "the concept of preservation or conservation treatment is quite foreign to the Gupapuyngu because theirs is a living culture and they're actively painting these designs. Joe has said, 'if this was back at home, we'd just bury it and make another one.'"

Men and woman testing glue on bark Conservator Samantha Hamilton demonstrating a conservation technique on some samples of bark.
Image: Ben Healley
Source: Museum Victoria
 

Sam had many questions for Joe and Milay. "There is a layer of meaning in each brushstroke, so if we directly apply adhesive to consolidate the paint, are we altering its cultural meaning? Is it better to document the painting with detailed photographs and leave it untouched? Also, these designs are body patterns worn only by men, so should female conservators be treating them?"

During the visit, Milay demonstrated the traditional techniques used by the original creators of the paintings. He ground and mixed charcoal, white clay and two types of ochre with water to prepare the paint. He also fashioned paintbrushes from grass stems and showed Sam and Lindy how djalkurrk (orchid stem) was used to bind only the background paint layer to the bark. Sam was particularly fascinated to learn this, as it was common understanding that the binder was used with every paint layer.

traditional Yolgnu painting materials Milay's painting kit: lumps of ochre and charcoal, grass stem paintbrushes and orchid, all brought to Melbourne from Arnhem Land.
Image: Ben Healley
Source: Museum Victoria

Hands applying ochre to bark Milay demonstrating how orchid stem is used to apply a background layer of rich red ochre to the bark slab.
Image: Ben Healley
Source: Museum Victoria
 

After seeing Sam's demonstrations, Joe and Milay advised that a technique called misting would be acceptable to the Gupapuyngu community and that no direct application of adhesive should be performed with a paintbrush. They also approved conservation's technique of stabilising split bark and agreed that Sam was the right person to perform the treatment.

Sam hopes that this project will have lasting impact. "MV conservators have consulted with community in the past and it's becoming more common around the world. Where possible, I'd like to see it continue as an ongoing practice especially with our Victorian Indigenous objects and the Koorie community." During the Bunjilaka redevelopment project Sam has been consulting with the Yulendj reference group, and is very excited about collaborating with Yorta Yorta Elders to determine a long term preservation plan for the historic possum skin cloak.

Links:

Ancestral Power and the Aesthetic is at the Albury Art Gallery until 18 November 2012

MV Blog: Ancestral Power opens in Benalla

MV News: Ancestral Power and the Aesthetic

NMAI Conservation Outreach

Agatha's cold cream

Author
by Kate C
Publish date
4 September 2012
Comments
Comments (2)

Legendary crime writer Dame Agatha Christie may have sold more novels than any other writer, but did you know she was also a pioneer in object conservation? Working in Iraq alongside her archaeologist husband Sir Max Mallowan, Christie used improvised tools and cold cream originally intended for her own face to clean thousands of excavated fragments known as the Nimrud Ivories.

lid of cold cream container Lid of a 19th century ceramic cold cream container excavated from Little Lon, Melbourne and part of MV's Little Lon Collection.
Source: Museum Victoria
 

Cold cream is a mixture (or emulsion) of water in oil used to clean and soften the skin. Its name originates from the cold feeling left when the water component draws evaporates from the skin. But why was it useful for ivory? And is it still used for that purpose today? Senior Conservator Helen Privett helps to preserve objects in Museum Victoria's collection and she was happy to talk about contemporary tricks of the trade.

'We wouldn't use cold cream, but we use moisturising agents like it, such as polyethylene glycol which you find in modern cosmetics," says Helen. "The reason why you might use something like that is that you don't want to get ivory too wet, because it absorbs water and then expands to different degrees in different directions... a kind of multidimensional swelling which can cause cracking and distortion."

"We've got data loggers in the Mesopotamia showcases to monitor the environmental conditions. The showcases containing ivories are all set to about 55 per cent relative humidity to make sure they don't get too wet or too dry."

Approaches to artefact conservation have changed profoundly since Agatha Christie's time, and not just in terms of technological advances. There have been philosophical changes too: now the focus is on the long-term stability of the objects, which sometimes means a hands-off approach. Importantly, conservators don't necessarily clean artefacts any more.

"One issue in archaeological conservation is that you're removing objects from where they've sat for thousands of years," explains Helen. "Sometimes they're actually quite stable in that environment, and it's better to leave something buried than to bring it out of the ground." In the case of shipwrecks and certain archaeological sites, reburial of artefacts is becoming an accepted technique for preservation.

When cleaning or other treatment is required, conservators turn to a variety of materials. Many are chemicals that you might have in your own home, such as methyl cellulose (found in toothpastes, artificial tears and moisturisers) which is a useful adhesive and a poultice base, and citric acid (found in soft drinks) which is a gentle way to remove corrosion.

Woman with bucket Senior Conservator Helen Privett holding a giant bucket of citric acid in the MV Conservation Lab.
Source: Museum Victoria
 

Helen describes the global community of conservators as open and willing to exchange information about new conservation techniques and materials through articles and online forums. "There are some adhesives, for example, that are made specifically for the conservation industry but because it's such a small field we tend to use materials from other industries. We do a lot of testing ourselves, particularly for new environmentally sustainable display materials."

Becoming a conservator usually requires a sound background in art history combined with broad training in materials science and applied chemistry. Then there's the tricky decision about which sub-specialty to enter; conservators can specialise in particular fields such as paintings, paper, or objects. For Helen, it was a single moment that led her to object conservation – seeing the Portland Vase in the British Museum. "It's very deep, intense translucent blue glass with a carved white relief. They've never been able to replicate how it was made. This amazing object was smashed into hundreds of pieces and has been put back together numerous times, so it's got this extraordinary history of manufacture, collection and conservation. It's my inspiration."

blue and white Roman vase The Portland Vase, perhaps from Rome, Italy, about AD 5-25.
Source: © Trustees of the British Museum

Not every object is as monumental as the Portland Vase, and Museum Victoria's collection encompasses many types of materials, including a few that are notoriously difficult to conserve. When asked about her least favourite material, Helen doesn't mince words. "I love plastics, but I hate PVC. It's got what we call 'inherent vice' – it will deteriorate under any circumstances and was never meant to last. Because of the chlorides in the polymer, when it starts to deteriorate it forms hydrochloric acid and basically eats itself to death. PVC objects start to get sticky or tacky, or stuck in a certain shape and they're just a nightmare."

Further reading:

The Art of the Conservator (1992). Andrew Eddy (editor), British Museum Press, London.

Ladies of the Field: Early Women Archaeologists and Their Search for Adventure (2010). Amanda Adams, Greystone Books, Canada.

Links:

Murder in Mesopotamia: Agatha Christie and Archaeology forum at Melbourne Museum on Sunday 9 September

'British Museum buys 3,000-year-old ivory carvings Agatha Christie cleaned with her face cream' (Daily Mail, 8 March 2011)

Australian Historic Shipwreck Preservation Project

Conservation OnLine

HV McKay crate

Author
by Liza Dale-Hallett
Publish date
27 December 2011
Comments
Comments (1)

Liza Dale-Hallett is a senior curator in the History and Technology Department. She is responsible for the Sustainable Futures Collection, which includes historical agricultural machinery.

Ken Porter, a former Transport Manager at agricultural machinery manufacturer Massey Ferguson, accidentally stumbled into heritage conservation when he rescued a wooden box from a dumpster in 1991. He thought the box might be some use to him at home, but noticed that a square of cardboard was nailed to it, reading: The plaster cast of H.V. McKay. Not to be opened until another one needed.

Ken Porter Ken Porter, Volunteer at Scienceworks, with the mysterious crate he rescued from a dumpster.
Image: Rodney Start
Source: Museum Victoria
 

For another five years Ken secretly rescued nearly 100 years of history of the McKay manufacturing enterprise. This 'rubbish' was squirreled away and subsequently offered to Museum Victoria where it now forms one of Australia's most significant industrial heritage collections.

'No one thinks of history. Until I found that box I didn't either. It takes a quirk of fate that keeps these things,' recalls Ken, now an Honorary Associate of Museum Victoria. Since 1996, Ken and 20 other ex-employees (with many more from around Australia) have been busy identifying and documenting the collection of 15,000 images, over 700 films, numerous objects, and over 5,000 trade publications.

H.V. McKay  |  Sunshine Harvester brochure Left: Portrait of Hugh Victor McKay. 1912. | Right: Seedtime and Harvest Shall Never Cease: H. V. McKay, General Implement Catalogue, Sunshine Harvester Works
Source: Museum Victoria
 

From humble beginnings, H.V. McKay created the largest industrial enterprise in the southern hemisphere. His equipment was widely used on farms across Australia and was exported to over 150 countries. Following McKay's death, his legacy to Australian agriculture continued through McKay Massey Harris, and later Massey Ferguson (Australia). In 1986, after a period of over 80 years of manufacturing in Sunshine, the company ceased production. This period of major change also included a significant 'clean up' of old company records, which is when Ken's rescue efforts began.

After so many years documenting the McKay Collection, the crate remained a mystery waiting to be revealed. What was inside? How could we open it without damaging the contents?

Michael Varcoe-Cocks, Conservator of Paintings at the National Gallery of Victoria (NGV), volunteered his expertise in radiography to help examine the construction and content of the crate before it was opened. Radiography reveals physical features not otherwise visible to the naked eye. It is often employed to better understand the condition and method of manufacture of a work of art, and doesn't harm the object.

Examining the x-ray films at NGV Examining the x-ray films at NGV.
Image: Justin Schooneman
Source: NGV
 

The x-ray was performed in the NGV's Technical Examination Room. Michael enclosed the crate in lead then passed a beam of x-rays through it. Film sensitive to x-rays recorded an image of the crate, inside and out, which provided useful information for MV Conservator Karen Fisher about how to open the crate. Karen used a Japanese Cat's Paw (mini crow bar) to gently lift the rear panels; inside were two profile reliefs of H.V. McKay, both in plaster, not a 'bust' as indicated on the outside of the crate.

MV Conservator Karen Fisher opening the crate with a Japanese Cat's Paw. MV Conservator Karen Fisher opening the crate with a Japanese Cat's Paw.
Image: Rodney Start
Source: Museum Victoria
 

two profile reliefs of H.V. McKay. The two profile reliefs of H.V. McKay.
Image: Rodney Start
Source: Museum Victoria
 

Karen then turned to the letter secured by drawing pins to the front of the crate. She used humidification and a heated spatula to make the paper more flexible and break the seal. The letter confirmed that Wallace Anderson was the sculptor commissioned to create the relief profiles. Anderson worked as an artist for the Australian War Museum, the Australian War Memorial and as an independent sculptor. Anderson's most famous works are 'Simpson and his Donkey' (1935), and busts of nine former Australian prime ministers located in the Ballarat Botanic Gardens (1939-45). He also created the bust of H.V. McKay now on display in The Melbourne Story.

We still don't know why the profiles were created or whose initials are represented on the lower edge of one of the plaster moulds... but after 20 years, the crate's contents are finally free.

Links:

H.V. McKay Sunshine Collection

About this blog

Updates on what's happening at Melbourne Museum, the Immigration Museum, Scienceworks, the Royal Exhibition Building, and beyond.

Categories