- 1). Gather seashells from the beach and collect cleaned and dried meat and poultry bones from your table. Bones should be washed and soaked in a dilute bleach solution and then thoroughly dried in the sun.
- 2). Mix up small batches of either plaster, cement or mortar mix in coffee cans by adding water slowly and stirring with paint sticks constantly and thoroughly until the mixture achieves the consistency of a thick cake batter. Mix up amounts that you can use quickly before it sets up.
- 3). Experiment with various combinations and consistencies. Cement and mortar mix will set up more slowly than plaster, but adding a few spoonfuls of plaster to cement or mortar mix to greatly reduce their setting time. Mortar mix alone makes the best "rock," as it has the appearance of sandstone. Cement looks much like limestone; plaster alone resembles chalk.
- 4). First make fossil seashell molds. Spoon your thick concrete "batter" mixture into a small open-topped cardboard box and spread it out with the paint stirring stick or spoon. Select several seashells and spray their outer surfaces with cooking oil spray.
- 5). Quickly but carefully depress the seashells evenly into the cement mix up to their rims, and then very carefully remove the shells, leaving their impressions in the concrete mix. Allow your fossil molds to dry for 24 hours.
- 6). When your fossil molds are dry and hardened, pull away the cardboard layer and rinse the molds under clean running water. Allow to dry. Spray molds and other fossils you create with a light coat of clear polyurethane if you wish or leave them as they are. Prevent molds and casts from sticking together by spraying molds with a thin coat of polyurethane and a thin coat of cooking oil after the polyurethane dries.
- 7). Make casts of your fossil molds or of animal footprints by centering an oiled tuna fish-sized can with both top and bottom removed over the mold or footprint you wish to cast. Spoon or pour in a thinner (more water) plaster/cement/mortar mixture to the rim of the tuna can and allow 24 hours to set up. Using plaster alone or mixing plaster in the cement or mortar mix will reduce the setting time, but it creates a softer "rock."
- 8). Create a fossil "death assemblage" of shells, bones or bones and shells by placing these items in a small open top cardboard box. Wet them down a bit to help cement mix to stick by spraying with a mist of water. A death assemblage is a group of fossils from organisms that weren't associated with each other when they were living; the fossils were brought together by natural processes like currents or tides after the organisms were dead.
- 9). Mix up a thinner pourable (more water) mixture of cement, mortar and plaster, and pour over the bone and shell assemblage. Pour slowly and carefully until the mixture reaches all of the bones and shells, but does not cover them completely. Jiggle and vibrate the box slightly as you pour to ensure coverage and to remove bubbles. Allow this bone/shell assemblage to set up and dry for at least 24 hours before you remove the cardboard and treat with polyurethane spray.
- 10
Leave your shell/bone death assemblage as is or cut into slabs on a wet saw if you wish to create slices (cross-sections) through the fossil. Spray with polyurethane to seal surfaces and to bring out fine details. These slices can be used as tiles if you wish.
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