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How to Make a Cast of a Dinasaur Footprint

Making a cast of a dinosaur footprint is a fun way to take a piece of natural history home with you and provides a close up look at these ancient creatures. To that end, there are a number of parks and museums that allow visitors to make casts of dinosaur footprints. Footprints are cast using plaster of Paris mix. The plaster molds to the footprint and captures all of the details. Once you understand how to make plaster casts, you can make casts of all sorts of footprints that you find in your outdoor adventures.

Things You'll Need

Shop brush
Cooking oil
Cloth rags
10 lbs. plaster of Paris
Water
Plastic pail
Paint stirrer
Metal ring with a larger diameter than footprint
Gloves

Instructions

- 1
  Brush the footprint off using a shop brush in order to clean off any dirt or debris. It is important to have a clean surface as the plaster will pick up even the smallest bits of debris.
- 2
  Apply cooking oil to a rag and rub the footprint with the oil. Make sure to coat the footprint thoroughly with the cooking oil. The oil will allow you to release the plaster from the footprint with ease.
- 3
  Mix 10 lbs. of plaster of Paris with 3 quarts of water in a plastic pail using a paint stirrer. The mixture will be runny at first; allow it to thicken slightly before pouring.
- 4
  Center the metal ring around the footprint. Wet cloth rags and wrap them around the ring to prevent the plaster of Paris from seeping out from under the ring when you first pour the plaster.
- 5
  Pour the plaster of Paris mix into the metal ring until it is level with the top edge of the ring. Allow the mix to dry for 20 to 30 minutes. Remove the rags and metal ring from the cast plaster. Let the cast dry for an additional 30 minutes. Lift the cast up from the footprint carefully with both hands.
- 6
  Wash the footprint off with water. Use the shop brush to brush the footprint clean. Rinse the footprint off with water once you have removed the remaining plaster.

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