February 28, 2011

CSI: DO Try This At Home!

Part of a CSI’s job is to investigate footprints. A good footprint is made after rain has fallen. Have you ever wondered how they collect those prints? Its pretty simple. You can even try it at home!

-Plaster of Paris (found at any hardware store)
-16 oz of water
-Casting frame. This can be made by nailing 4 boards together in a square.
-Plastic bowl or plastic bag
-Footprint in the dirt/mud
-Optional: plastic spoon for mixing

     First, pour the water in a bowl or bag. Then add 1 cup of Plaster of Paris at a time to the water, mixing it in. braytonWith the bowl, it can be done with the plastic spoon, or just use your fingers! With the bag, close it and shake it up. Make sure there are no clumps. Keep adding in the Plaster of Paris until it’s consistency of gravy.
      Put the casting frame around the print. Spray the print with hair spray. Pour the plaster mix into the frame. The mix should harden within 30 minutes, but its best to wait a few hours, to be sure. Lift the frame off and turn the hardened plaster over. Clean off the excess dirt/mud and you should have a raised impression of the footprint.
      If the weather doesn’t allow for it to be done outside, after you make the plaster mix, pour it into a shoe box. Take a shoe and spray the bottom with hairspray. Press the shoe into the mix. Wait a few hours and pull the shoe off. There should be a nice impression of the shoe.