I recently zoomed with two fellow bone lovers, both of whom have markedly elevated my respect for bones displayed in museums, to which I am gravitationally attracted.  

Mariana Di Giacomo is a natural history conservator at the Yale Peabody Museum of Natural History, and Melissa King is a preventive conservator currently on fellowship at the Smithsonian Institution. As they explained to me, a lot more than meets the eye goes into display and protection of museum fossils and bones, which are used both for education and research.

T rex vertebrae on plaster mount under review by conservator Mariana Di Giacomo.
Tyrannosaurus rex, USNM 555000. Courtesy U.S. Army Corps of
Engineers, Omaha District and The Museum of the Rockies, Montana State
University. Photo by Kate D. Sherwood, Smithsonian.

https://twitter.com/NMNH/status/1052924081782366209?s=19

For instance, should a bone that was broken when discovered be glued back together? Doing so keeps the two parts from getting misplaced and demonstrates more closely its real-life self, but reassembly precludes access to the bone’s interior for any analysis–perhaps today for DNA or protein, tomorrow for some presently unknown test. As a compromise between reattaching the fragments and leaving them dissociated, they may make a mount that supports the pieces in their original orientation but without physically joining them.

Superglue or Gorilla Glue? No and no, emphatically. Conservators use B-72 on bone, as they do on ceramic and glass. It is a thermoplastic, non-yellowing, durable resin. They also use B-72 as a means to permanently and non-destructively label bones and fossils. They paint on a stripe of resin, hand write the identification with non-penetrating ink, and then protect the ID with another layer of B-72.

Mariana rolled her eyes when I asked what mistakes had been made in the past. With good intentions, fossils and bones have been sealed with wax, varnish, and other coatings that degrade in unsuspected ways and greatly damage the specimen’s appearance and study value. Without any surface treatment, bones and fossils on display weather away far more slowly than they would at their original discovery site; but museums contain their own destructive perils, which include sunlight, fluctuating temperature and humidity, and dust. Conservation of biological specimens parallels that of oil paintings and is approached with similar delicacy. Then before a specimen goes into a display case, the materials and coatings comprising the case are tested for any off-gassing that could damage the item. Should the display case be air-tight to prevent exposure to environmental pollutants such as acetic acid, which will dissolve bone? Or would sealing the case cause its own set of problems?

Musical Instrument Museum, Phoenix

Bone that has been repurposed to make or decorate weapons and musical instruments also creates problems, particularly when it has been inset into other materials, for instance wood, which has its own conservation demands. Then for leather, feathers, cloth and other biologically derived materials embellishing crafted bone artefacts, protection from insects and vermin is key. Conservators by necessity become verminologists, learn the life cycles of these spoilers, and apply integrated pest management, which consists of various biologic, physical, and chemical means for protecting the collection while minimizing overall health and environmental issues. A non-living menace is dust, much of which is partially decomposed animal matter and which is great fodder for vermin.

Bill Simpson at the Field Museum giving Sue a periodic air bath.

Gigantic skeletal specimens, too large to encase, need to be delicately dusted from time to time; but particularly when they are extraordinarily tall or suspended from the ceiling, regular housecleaning becomes problematic. It might be easier to routinely display skeletal replicas and take them down for a bath periodically, but museum visitors like to see the real specimens. This poses its own set of problems because assembling fossil bones into a lifelike stance requires heavy metal supports, and the current trend is to mount specimens such that any single bone can be removed for analysis without disassembling the entire display. This, of course, makes the support system far more complex and visible.

Conversely, displaying replicas and leaving the real specimens in the storeroom is not without risk either. The original pieces, if not carefully labelled and catalogued, can get separated, misplaced, damaged, or lost, even if carefully protected in padded boxes inside of cabinet drawers. Of course, that degree of protection is not possible for fossils that are measured in feet and in hundreds of pounds.

Overall, my conversation with Mariana and Melissa heightened my appreciation for the care that goes into bones displayed and preserved in museums. Fine art conservation and restoration make the news from time to time. Bone deserves (and is receiving) the same level of care and should be equally celebrated. 


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Follow up on the recent post: Marking Time in Prague. A reader commented that the Prague Old Town Square in front of the ancient clock was the local pickpockets’ favorite location. I can imagine: everybody relaxed, looking up, likely getting jostled a bit, robbed–another peril avoided by traveling virtually!

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