How to Make Fossil Reproductions

You can make imitations of fossil fish with plaster.

Making fossil reproductions can be either an educational classroom activity or a home craft project. Finding real fossils is not always very easy, but you can make realistic imitations yourself. Fossils form as an animal or plant becomes covered with sediment and its organic body slowly replaced by minerals. To make your own fossils, you imitate the process, but over a far shorter time frame.

Things You'll Need

• Plaster of paris
• Bowl
• Tempera paint
• Box
• Clean animal bones, fish skeletons, shells or leaves
• Petroleum jelly

Instructions

1. Mix the plaster of paris with water in a bowl until it is smooth and thick but still pourable. Add more water or plaster as necessary until you get the right consistency.

2. Add paint to change the color of your "rock." For a natural, subtle look, mix a little yellow, red or gray with a dot of brown paint.

3. Pour one or two inches of the mixture into your box.

4. Coat the animal bone, fish skeleton, shell or leaf you wish to "fossilize" in petroleum jelly.

5. Press the object firmly into the plaster. Leave enough outside the plaster to get hold of later.

6. Leave for a day. When the plaster is completely dry, carefully remove the object. You now have a mold.

7. Coat the entire top surface of the mold with petroleum jelly.

8. Mix up a second batch of plaster of paris and pour over the mold to a depth of one or two inches.

9. Wait until this is dry, then carefully pull or cut away the box. Separate the two layers. The top layer, your "fossil," will look more natural if you chip away sharp edges and corners.

Tips & Warnings

• Pushing a nail or piece of bamboo through the top layer of plaster during step eight provides a hole to hang your fossil on later.

References

• U.S. National Parks Service: National Fossil Day, Educational Activities