Carnegie Museum of Natural History

One of the Four Carnegie Museums of Pittsburgh

Gretchen Anderson

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Ice and Snow: The effects of temperature

Winter is coming! The temperature is dropping. The first snow fall in the Laurel Highlands was gorgeous. The snow was hanging on the trees and piling up around the cabin we were staying in. Driving home to Pittsburgh in the storm was not so fun, reminding me of scenes from Game of Thrones and my childhood. By the next morning the beauty of the snow was already receding as the temperatures climbed in Pittsburgh.

Snow laden pine tree at Powdermill Nature Reserve. December 1, 2020.

Full disclosure, I love winter – but then I am from Minnesota where one either embraces the cold and snow or hibernates for the long cold days. We celebrate winter in Minnesota. The St. Paul Winter Carnival began in 1887, when some east coast journalists claimed that the state was as inhabitable as Siberia. The annual festival developed its own legend with events like ice skating, a night parade, a full-sized ice palace, and an ice sculpting contest. It can be magical. The carnival is in January – often the coldest time of the year, with sub-zero temperatures and bitter cold winds. However, occasionally there is a thaw.

The ice sculpting contest is in held in Rice Park, across from the Courthouse and St. Paul Public Library (yes, it is one of the Carnegie Libraries). Dozens of intricate sculptures are carved each year. When I lived in the city, I used to walk across the park daily on my way to work from my bus stop. It was fascinating to watch the sculptures take form. Artists would use hot water to build blocks of ice into the basic form, then use chain saws, chisels and more hot water to carve and sculpt. My favorites were the fanciful forms that were crystal clear. Standard practices changed during the heat wave of 2008. Temperatures rose to the mid 30’s during the day and refreeze each night. With each passing day the sculptures deformed and lost definition. That year the judging did not take place.

Within a few days this elegant swan went from a crystal-clear sculpture to the distorted image you see here. What a little warmth will do! The extreme and fluctuating temperatures that we experience during the winter months pose a challenge. Have you ever wondered why potholes develop or why slabs of the sidewalk tilt? What we think of as the ground freezing is mostly the water in the ground freezing. As this happens the water expands (think ice cubes). As the temperature warms up, above 32 degrees Fahrenheit, the ground subsides. Of course, it does not do this in a uniform manner – some areas freeze faster and thaw faster than others. Rocks and soil shift. The hard surface of the road or sidewalk is dislodged. The concrete slab tilts or the pothole develops. Of course, heavy traffic from cars and trucks just aggravates the situation. The more often the temperature fluctuates between freezing and thawing – the worse the problem is and the more damage to your car as you hit that pothole.

As the Objects Conservator at the Carnegie Museum of Natural History, I do not have to worry too much about these kinds of extreme temperature fluctuations. Most of the collections under my care are quite happy at the same temperatures that we humans find comfortable. Most materials are stable enough to survive moderate fluctuations, which can be maintained using heating and air-conditioning.

Gretchen Anderson is a conservator and the head of the Section of Conservation at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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Risk Assessment, or how to keep your collection intact

By Gretchen Anderson, Conservator, and  Suzanne B. McLaren, Chair of Collections

What are the risks to a museum’s collection?  

specimen in a box with partially eaten label

Figure 1: The risks of damage are varied. This photograph illustrates the potential risk of loss of data. The label has been partially eaten by silverfish, damaging not only the paper but ingesting the all-important data about this specific specimen.  

The museum is currently engaged in a two-year Risk Assessment process funded by a grant from the Institute of Museum and Library Services (IMLS). We are reviewing a spectrum of potential risks to our collections. This includes everything from fire and water damage to earthquake and pest damage that could affect the Museum’s more than twenty million specimens and objects, both behind the scenes and on exhibit.

Forty staff members from across the museum attended a weeklong workshop led by our consultant, Rob Waller of Protect Heritage, who has been refining a model of how to quantify risks for more than twenty-five years. This was meant to get us all on the same page when we begin to focus on our individual collections.  The workshop offered everyone a chance to see and talk about their individual collections. For most of us, we call this fun. This gave each of us an appreciation for risks to distinct types of collection material. The risk for stone and metal will be quite different than the risk for organic material like birds and plants.

researchers around a table

Figure 2: Curators, collection managers, curatorial assistants, educators, exhibits staff, engineers, maintenance and security staff attended the workshop.

researchers looking at computer

Figure 3: The workshop had several days of small group interaction. Here Vertebrate Paleontology Collection Technician Linsly Church, Anthropology Collection Manager Deborah Harding, Collection Associate Marion Burgwin and Minerals Collection Manager Debra Wilson discuss definitions of risk.

We hired Collection Associate Marion Burgwin to work with various staff members on gathering quantitative information on risk from each collection. Collections are divided into twenty-nine units, based on scientific discipline, preservation type and primary use. For example, the Bird collection has four units: study skins & skeletons, nests & eggs, taxidermy, and fluid collections. It is detailed and tedious work – but Marion also gets to see all the cool collections.

researchers looking at specimens

Figure 4: Birds Collection Manager Steve Rogers and Collection Associate Marion Burgwin viewing a collection of bird wings. Burgwin is entering the data directly into the Preservation Heritage Data Base.

Nearly one year into the project, Conservator Gretchen Anderson and Chair of Collections Suzanne McLaren had the good fortune to present the project and network with colleagues at the annual conference of the Society for the Preservation of Natural History Collections in New Zealand.  Sharing information like this is an important aspect of the support we receive from agencies like IMLS.

two researchers and their poster

Figure 5: McLaren and Anderson with the Risk Assessment poster at the 2018 SPNHC annual conference, Dunedin New Zealand.  

yellow-eyed penguin

Figure 6: A New Zealand native  – a highly endangered yellow-eyed penguin.

 

 

Gretchen Anderson is a conservator and the head of the Section of Conservation and Suzanne McLaren is the collection manager for the Section of Mammals at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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Timber Wolf Diorama Restored

timber wolf diorama being restored

Have you seen the new wolf diorama in our redesigned gift shop?

Like many of the other fixtures in the shop, the diorama was pulled out of storage and reused. But the journey from storage to store wasn’t as simple as just dusting off the case. Museum conservators spent hours
cleaning, repairing, and researching this piece before it was put on display last month.

Conservator Gretchen Anderson spent several days examining, photographing, and researching the diorama. The Carnegie archives revealed that the timber wolf was collected near Denali National Park in Alaska. The taxidermy mount was created in 1928 by well-known taxidermist Remi Santens. The background paintings in the diorama weren’t created until the late 1950s or early 1960s.

To prepare the diorama, Gretchen had to carefully clean the background paintings, and groom the wolf’s fur. The wolf’s paws were damaged when they were moved and disconnected from the mount. Gretchen slowly repaired the paw by re-adhering the wolf’s hide to the plaster with a papier-mâché technique that used special, non-acidic paper.

Next time you’re at the museum, check out the new gift shop and take a closer look at the timber wolf and his beautifully restored paws!

timber wolf paw
timber wolf paw being restored

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5 Surprising Conservation Facts

cleaning a panda diorama

by Kathleen Bodenlos

Gretchen Anderson is a conservator at Carnegie Museum of Natural History. She is restoring a panda diorama that will be prominently placed in our newly renovated gift shop. (Stay tuned for more on the gift shop in the next few weeks).

Here are 5 surprising things about conservation of a diorama.
1. Less is more: Use as few chemicals as possible

  • Soot sponges, water, and vacuums are the top
    choices in lieu of harsh chemicals. Water is one of the most powerful solvents!
  • Gretchen begins with a fan brush and a HEPA (high-efficiency particulate air filter) vacuum to remove as much dust and arsenic traces as possible.
  • She is wearing a protective face mask and gloves to protect herself from any arsenic that might be stirred up.
  • Soot sponges are a rubber sponge designed to absorb soot and are used dry. Another handy tool is a makeup sponge. A make-up sponge is used when just a little tiny bit of water is needed to move the dirt.
  • Particulate dust (dust, dirt and soot) is extremely damaging to museum collections. It is best to remove it.
sponge covered in dust

2. Some conservationists also do a little restoration on paint

  •  When in doubt go lighter to match a color
  • Think impressionism and mottle with several colors if possible. A good example is the natural colors on a rock.
restored panda diorama

3. Move ‘em up and head ’em out—RAWHIDE!

  • For many older dioramas, the skin of the animal is literally a raw hide. They are often treated with arsenic to keep the hide from becoming infested with insects and being eaten/damaged
  • Mercury, and other pesticides were also used to prevent insect attack on some museum collections.
  • A sealed exhibit case helps to keep the diorama safe from damage. Dust and insects are kept out. If there are any pesticides inside the case these are kept in – protecting the public.
  • Plant material
    ·  Not all of it is fake. Some of the actual plant materials are painted to make them look alive
    ·  Even a non-expert can discern what is fake and what is real upon close examination
  •  Save money—use less
    ·  When washing clothes the soap is to keep dirt from settling back on clothes
    ·  Agitation and water are the real cleaner
    ·  Use 1/3 less soap and your clothes will be clean
    and you will ensure that all the soap is removed which will help protect your
    skin

Kathleen Bodenlos is the Director of Marketing at Carnegie Museum of Natural History. Museum employees are encouraged to write about their unique experiences.