Making copies

SUMMARY: Peter Fenton, technician at the Royal Ontario Museum, demonstrates how to make copies of Burgess Shale-type fossils for display in other museums. (3:49)

Fenton on camera
DESCRIPTION: Fenton on camera

"When a museum is creating a display, for instance of Burgess Shale material, they'll contact us because we have such an incredible collection of Burgess material. And they'll ask to borrow some material so they can put it in their exhibition. Of course, everybody wants the best specimens possible, then there are only so many of them that can go around. So usually what will happen then is we will provide them with a series of casts of specimens. And it's not just us. If you look at many museums, their dinosaur galleries, "

comparison of Burgess Shale fossil with copy
DESCRIPTION: comparison of Burgess Shale fossil with copy

"a lot of the specimens you're seeing are casts. Now, a cast is a very accurate replica of the fossil."

close-up of fossil
DESCRIPTION: close-up of fossil

"That's what we're going to cast, where I'll show you what the casting process is."

Fenton shows modeling clay
DESCRIPTION: Fenton shows modeling clay

"The very first thing we do is start with some modeling clay, just the standard stuff a lot of people have played around with. I roll out a nice big sheet of it like this, fairly thin, and this is going to sort of support"

pressing back of fossil into modeling clay
DESCRIPTION: pressing back of fossil into modeling clay

"the specimen as we are casting it, as we are actually making the mold. Then what I have to do is sort of a long, drawn-out process,"

sealing edges of fossil with modeling clay
DESCRIPTION: sealing edges of fossil with modeling clay

"I just take little bits of modeling clay, you can sort of roll it out with your hands to make, kind of like little worms, and I'm just going to use this to sort of fill in around the edge. Because when I actually pour the liquid material that forms the mold, I don't want it creeping underneath the specimen itself."

rolling out clay, cutting into strips
DESCRIPTION: rolling out clay, cutting into strips

"The next thing we have to do is we have to build walls. And we build walls pretty much the same way, I'll just re- … it's pretty much like craft class. And that wall I then place along there. I'll cut a straight edge there. And I just press it into place."

assembling strips of clay into a container around the fossil
DESCRIPTION: assembling strips of clay into a container around the fossil

"Now I want to make sure this wall actually is probably at least 1 or 2 cm higher than the highest point of the fossil. You'll sort of see why as we go. So basically, I'd say we have the fossil in kind of like a little bathtub of this silicone-based modeling clay. Now we have prepared this to make our first mold."

Fenton displays chemicals which will be used to make the mold
DESCRIPTION: Fenton displays chemicals which will be used to make the mold

"We have, it's a two-part mixture. One comes in this large container. It's a 10 to 1 mixture, in other words for every ten ounces of this we need an ounce of the catalyst, this nice, bright green catalyst. We mix it, we then put it in a vacuum chamber to remove any bubbles or as many bubbles as we can. Once it's stopped frothing away in the vacuum chamber, we can pour it into our little bathtub with the fossil in it. And within 24 hours it will set up."

peeling back mold from fossil
DESCRIPTION: peeling back mold from fossil

"This then, actually very easily peels off the fossil. And that is our mold. So this is a negative"

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