Mold in paleontology can mean two things. The first (bad kind) happens when you get water trapped in your field jackets (plastered specimens), it sits for ages, and grows a nice layer of Becky-breathing-impairing mold. The second (good kind) is when we need to make a copy of a fossil. Not just any copy, but an exact copy. This could be because a fossil is one-of-a-kind, and we need to show it to other researchers without fear of damaging the original. Or maybe it’s a really neat specimen we want to give away as a souvenir or include as a hands-on demonstration, allowing people to touch the copy.

A mold could be a simple one-sided “dump” mold, where only half of a fossil is copied. This is good for a display mount, perhaps a nice shelf specimen, or giveaways to kids. If the whole fossil is needed, we could need a two-, three-, five-, or even ten-sided mold (depending on the complexity of the fossil). No matter what size mold is created, we make sure the fossil can take the stress. Generally a very thin sealer is put on the fossil to make sure the silicone (our mold material of choice) doesn’t sneak into cracks. Then, we figure out where the pour spout will be and any vents. Anything projecting to the side above the spout or vents can trap air bubbles – so we make sure everything leads up and out. In metal casting, this is called your “sprue” system.

Walls keep the silicone in a mold while it sets. Some people use wood or clay – We use LEGOs! They can make any shape, the clay doesn’t stick to them, the silicone doesn’t stick to them, plaster doesn’t stick to them – they’re perfect to use and reuse. If you notice an odd brick pattern on the sides of all my molds, that’s why.

Sometimes part of the fossil being molded will be embedded in clay (sulfur-free, or my silicone won’t set). As the clay is sculpted around the fossil, I have to imagine it as future silicone. No undercuts or thin spots, or else the silicone will be very difficult to remove and put back together again. The initial silicone is poured on top of the clay/fossil combo and left to cure. Once cured, a mother-mold may be added – this is a stiff backing, which could be plaster or fiberglass to add support later. The mold is flipped over, the clay removed, and a release agent placed on the now-visible silicone we just let cure. Silicone likes to stick to itself, so we need to put a thin barrier in place. Vaseline works great and is inexpensive. We repeat the silicone/mother mold process on the other side, or sides, depending on how many pieces a mold needs to be. Ta da! After everything is cured, the fossil is removed, and the mold is ready to go!

Multi-fossil mold, to reduce the amount of LEGOs used. Clay backing is visible.

Clay backing has been removed, and the first pour (opposite side) of silicone can be seen surrounding the fossil. Clay pour-spout and vent (bottom) left in during the second silicone pour.

A thin coat of silicone poured over fossils, and then a thicker coat. This helps to reduce any bubbles our vacuum chamber misses.

A small mother mold consisting of plaster and cheesecloth helps add rigidity to the end mold. The LEGOs and fossil will be removed next, when the mold is split apart.

Fort Totten, pictured in 1878. The hospital, with its unique dome, can be seen in the center of the photo. SHSND B0037

Work continues on the restoration of the historic hospital/cafeteria building at Fort Totten State Historic Site. One of the largest buildings at Fort Totten, it operated as a hospital and chapel during the time the site functioned as a military post. After the military abandoned the site in 1890, it became a boarding school for Indian children, and the hospital was converted into the cafeteria and kitchen. Today, the hospital/cafeteria is home to the Lake Region Pioneer Daughters who have housed their museum and collection at the site for over 50 years. In preparation for contractors, SHSND staff worked with the Pioneer Daughters and volunteers from the Lake Region Heritage Center to carefully pack and relocate the extensive collections in the building. Once the collections were moved, contractors from RDA Inc. (Fargo) began rebuilding a central load-bearing wall that was in desperate need of repair. Over several years, the wall had begun to shift and bow precariously and was, at that point, structurally unsafe. The wall was completed in November 2015, making room for mechanical and electrical contractors who are currently installing a new HVAC system and updating electrical systems throughout the building.

In October 2015, the central load-bearing wall in the hospital/cafeteria was completely rebuilt.

With a $500,000 appropriation from the 2015 North Dakota Legislative Session and a commitment of $100,000 from the Fort Totten Foundation, the work on the building will progress much further than the State Historical Society had previously anticipated. Designs for a new exhibit space, which will interpret the hospital, cafeteria and the Pioneer Daughters collection, is underway. The State Historical Society is also working closely with the North Dakota State Information Technology Department to best determine the technology needs for the building and how to best anticipate the long term needs for the site.

The hospital/cafeteria at Fort Totten State Historic Site pictured present day.

The summer of 2016 will likely see the completion of the electrical work, first story window restoration, interior painting, floor refinishing, installation of the HVAC system, and exhibit development. We also anticipate the restoration of the historic dome that sat atop the building if funding allows. Recent research suggests the dome (pictured in historic photographs) was used as an ether dome for surgeries during the military post era at the fort—providing much needed light in an era before electricity. The addition of the dome structure will be a unique feature to Fort Totten State Historic Site. SHSND is excited about the progress of construction.