Making a cast of your footprint.
There are many casting materials used for casting footprints such as sulfur, plaster, foam, stone (dental) or silicone. Plaster of Paris has been commonly used in the past and dental stone is recommended nowadays for the collection of 3D footwear evidence. Below, you will find step-by-step short instruction how to both of the methods:
1. Leave your shoe print / footprint in the damp sand or other wet soil (e.g. muddy puddle in the forest path) – the deeper your impression will be the better casting results you will get. It will be also easier to make a cast if you leave impression in a thick mud rather then watery one (the impression will be less fragile.
2. Carefully remove any leafs, small stones or loose soil from around the edge of the area you want to be cast.
3. Prepare your casting material:
- Plaster of Paris.
Mix plaster with the water (water volume should be about 2/3 the volume of the plaster). Pour two parts plaster mix to one part water into mixing cup (flexible plastic, paper or rubber) or into a plastic bag. Allow plaster to sit a minute or two before mixing. You can stir your mixture with plastic spoon or popsicle stick until smooth. If using plastic bag the mixture can then be kneaded through the bag until properly mixed. You can add more water or plaster (if required) to get an even and smooth consistency (should be about as thick as ketchup).
- Dental stone.
Mix dental stone with the water (approximately 2 lb of dental stone and approximately 10 oz of water). Stir continuously for a minimum of 3-5 minutes so that the powder can thoroughly absorb the water. Add more water or dental stone if required – the mixture should be about as thick as heavy cream.
4. Once mixture is ready, pour the casting material from one end of the impression and allow it to flow along the print. Do not pour it directly into the middle of the impression as it can distort the detail of your impression. If your mixture is in the plastic bag, you can cut the bag in one corner which helps you spread the casting material easily.
5. Ensure the impression is completely covered and filled evenly. If necessary, additional casting material can be poured over the top of the original cast to complete the process.
6. Once the impression is completely filled tap the surface with a ruler or a stick to make any air bubbles within the casting material rise to the top.
7. Allow your casting material to fully dry and thoroughly harden before lifting.
8. With the use of trowel or spade lift the cast from the ground. Dig into the ground a few inches away from the cast to avoid breaking the cast.
9. Allow the removed cast to thoroughly dry for 48 hours prior to any attempts to remove any soil adhering to the bottom of the cast.
10. Soil or sand can be carefully removed from casts using a soft brush (toothbrush or paintbrush) and water.