bottle of Elmer's glue








tube of super glue

Super Sue Meets Super Glue



A little skull, about as big as a mid-size dog.

Hard-headed: The skull of this mammal, called an oreodont,
needed no consolidation.

Sue 'n super glue
Most fossils come to the surface after the sedimentary rocks that held them captive for so long erode away. Like the rock holding them, fossils tend to be fractured, fragmented and friable. In other words, they have a habit of busting apart as soon as you try to move them. Blame sunlight, water and freezing. We're thinking dust unto dust...

A lot is at stake: Bill Mason, a producer of fossil-preparation supplies, says that at one location, 80 percent of the fossil-bearing rocks turned to dust during removal. Once upon a time, fossil hunters solved the problem by dousing fossils with Elmer's glue, shellac, beeswax, even Bakelite -- an early plastic.

Many consolidants, including the commonly used shellac, didn't penetrate, so even if they reinforced the surface, the insides remained weak, says Mason. "It's like adding strength by painting a barn."

And the results were unpredictable: "I've encountered a lot of things that were really nasty" among old fossil collections, says Joseph Skulan, a postdoctoral fellow in geology at University of Wisconsin-Madison. "They turn to chewing gum, and you don't know what they were."

Light-gray epoxy on dark gray fossil.
Even after they're consolidated, fossils may be fragmented. Epoxy bonds this fossil together.

Only skin deep
The field of fossil preparation has gotten a bit more scientific lately, with a shift toward higher-tech adhesives like epoxy and cyanoacrylates -- think super glue. Mason, who turned his talents to stabilization after 42 years in the adhesives industry, tested various cyanoacrylate compounds in the field, and found some that quickly penetrate tiny crevices, then harden to strengthen the fossil.

Although many, perhaps most, fossils will fall apart in the field or lab unless they are consolidated, the chemicals are controversial. While Mason touts the advantages of his products, others question their longevity. "Cyanoacrylates are not archival, yet a lot of us use them," says Bill Simpson, chief preparator at the Field Museum of Natural History, and a mastermind of the Sue preparation.

"We have misgivings," Simpson says, "but they do things that no other glues can do" because they penetrate at full strength rather than after dilution, as is true of epoxy glue. The down side?: "Supposedly, they will go bad in 20 to 30 years, and will start getting sticky," Simpson says. "That's obviously not a good thing."

While the Black Hills Institute, which excavated Sue a decade ago, used large amounts of cyanoacrylates to stabilize Sue in the ground, the Field Museum uses the glues primarily for small specimens, where nothing else would work.

'nuf chemistry. Is that fossil preparator holding a jackhammer???


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