By Ian Morrison, Technician, Vertebrate Palaeontology
I recently returned from a trip to the The Field Museum of Natural History in Chicago (along with co-op student Berkley Mackenzie-Bird) to pick up fossils for the upcoming show, Ultimate Dinosaurs: Giants from Gondwana. We brought back four specimens: a 6-foot long (1.8m) femur; a 4-foot long (1.2m) tibia from South America; 7 articulated sauropod caudals from Madagascar; and a block containing articulated posterior cervicals of a theropod from Antarctica. Before we could drive them back to the Royal Ontario Museum, support jackets needed to be made to protect and secure the fossils for the trip.
We make support jackets with plastic wrap, masking and duct tape, polyester felt, fibreglass, and gypsum cement.
We cover the specimen in plastic film, holding it in place with masking tape to protect the fossil from the gypsum cement and water mixture we layer over the polyester felt.
We cover the fossil with polyester felt cutting and sewing it together to create a fitted covering. Polyester felt is used to protect and cushion the fossil from the hard cement outer covering.
The felt is cut, shaped, and sewn to fit the complex shapes of the fossil. Here, Berkley is creating the custom polyester felt covering for the femur.
To make the cement outer layer, 50ml fibreglass is cut into squares, soaked with gypsum cement and layered on top of the polyester felt.
The support jacket is used in two ways: to cradle the fossil when we transport it and when we need to turn the fossil over to see the other side. The polyester felt creates a soft cushion right next to the bone and the fibreglass reinforced gypsum cement is a strong support to cradle the fragile bone along its whole surface so it does not break under its own weight.
Once the fibreglass layer is completed, the jacket is almost complete. We need to let it dry and trim the edge to make it smooth.
We use a jigsaw to trim the edges. We trim the edge of the support jacket smoothing out the rough edges making it easier to handle.