Digging in - fossil workshop tips

Ann Nicol

It's always great to have an article develop from a BIG CHAT thread! Here Ann Nicol from the Pitt-Rivers Museum shares a few thoughts and photographs on using embedded fossils in a public workshop setting.

In true cookbook style lets start with a recipe:

Recipe for fossil replicas
2 parts Ciment fondue
2 parts sandpit sand
1 part water (with 1 tiny drop washing up detergent added - helps free the fossil from the mould)
silicon rubber fossil moulds (sorry, don't know how to make these, I found a friendly geological conservator/technician to supply!)

Method
In a plastic mixing bowl, chuck in dry materials and mix up. Add water (amount may vary depending on how wet sand is) and mix thoroughly. Dip moulds in water + detergent (to help reduce bubble formation in the moulds).
Pour in mixture. Tap to release any trapped air bubbles.
Put moulds in plastic bags (to keep moist when curing) and leave 24 hours to set. Turn out and trim edges if necessary.

For matrix to embed fossils
1 litre granulated wax
2 litres sandpit sand
4 desertspoons Vaseline, some wax dye if you want to create colour (I used a bit of yellow / blue / red which created a kind of muddy brown/grey colour)

In some kind of melting vessel (I used a 5l tin can in a water bath arrangement in a wax melting pot), put in the wax, Vaseline and dyes. Leave to melt. Add sand, a bit at a time and mix in with long wooden spoon. Hard work!

Make up by embedding fossils in sand/wax mixture and leave to set.
Embed lots in a tray or individually (as I did) in foil take away containers. You can get about 10 smallish fossils embedded using this amount of matrix, if you're careful not to use too much. Leave for a couple of hours and turn out, and leave until cold for maximum hardness. The Vaseline makes it a bit softer for little fingers.
Experiment with quantities.

Children should wear goggles and possibly gloves, but there's nothing too hazardous here. To dig out the fossils, use some wooden implements and paintbrushes to re-create the paleontologist experience!

Quite messy when the extracting takes place - have plenty of newspaper around. You can collect and re-use the matrix.

What happened?
We ran pre-booked 45 minute sessions for 20 people at a time (which equated to about 15 or so kids in each one). When advertising / booking, it is worth remembering to state the ages it's suitable for (I would say maybe 6 years upwards). They were all sat around tables, which made it easier to manage.

Before the fossil digging commenced, we did an activity with a time-line to think about the scale of geological time and the idea of extinctions. This was followed by looking and handling some real fossils and trying to figure out what they were.

Then we got kitted up in gloves and goggles (if people wanted them), and with plenty of newspaper around to catch the bits, we started excavating. Each person had a fossil embedded in a block and they used wooden sculpting tools and cheap paintbrushes to uncover the fossils.

The consistency of the matrix was really good, and a couple of parents commented that it was better than some of the kits around at the moment you can buy off the shelf in shops like "The Natural World".

Definitely worth doing, though quite a lot of preparation work was required. Great if you want to create a good quality visitor experience for a few selected visitors. Not so good for large numbers or general un-booked visitors.

Ann Nicol is Audience Development Researcher at the Pitt Rivers Museum &
Oxford University Museum of Natural History

Newsletter Spring 2002 Contents

Fabricators' Event 2001
Skagen Odde Natur Center, Denmark
Museums Service Placement
Accessing SETNET
Fossil workshop tips
Going free entry - what are its effects?
Scientists meet the public
BIG AGM 2001 Chair's Report