Lab 4: Casting Footwear and Tire Impressions.
Lab 4: Casting Footwear and Tire Impressions.
Supplies Needed:
1 – Plastic re-sealable gallon storage bag (baggie)
1 – Knife or small screw driver
2 – Pounds of Plaster of Paris (available at Wal-Mart or Lowes)
1 – Butter knife (or similar object)
1 – Measuring cup to measure water
1 – Cheap can hairspray
Lab 4: Casting Footwear and Tire Impressions
Instructions:
A. First: Locate or create a footprint or a tire track in a dirt area. If you are creating your own impression, rather than an existing impression, you may wish to moisten the soil prior to making your impression.
B. Obtain the Plaster of Paris, water and a container so you can use it immediately after mixing.
C. Read the instructions on the box of Plaster of Paris on the mixing of the product.
D. Following the instructions regarding mixing the water and the powder, DO NOT ADD TOO MUCH WATER – FOLLOW THE INSTRUCTIONS ACCOMPANYING THE PLASTER OF PARIS. This should be a sufficient amount to make a casting approximately 12 inches long, by the width of the tire or shoe print, and with a thickness of approximately ½ inch. I would suggest you use the entire box to cover an area about the size of a shoe box and a thickness of ½ inch.
E. Once you have completed the mixing process, spray the entire impression with a moderate covering of hairspray. Be sure not to get so close to the impression to allow the force of aerosol spray to blow portions of your impressions away. Allow the hairspray to dry.
F. Gently pour the thick viscous substance (Plaster of Paris) onto the impression that you have located or created.
G. Using the blade of a common butter knife gently pat the top of the wet Plaster of Paris, ensuring that the substance adequately fills the impression and is patted into all crevices.
- H. After patting the Plaster of Paris into the impression, let it set for approximately 30 minutes.
- I. Before lifting, tap on the top of the impression and listen for a sound that will indicate that it is solid and dry. If it does not sound as if you are tapping on solid stone, continue to let it dry.
- J. Once the casting is dry, take the edges of your butter knife and gently lift the casting from the impression. It is best to pry all edges loose before attempting to lift the cast.
- K. Take your cast to a water outlet, such as a water hose or a utility sink, and rinse the dirt from the bottom of your cast. This should reveal a usable casting of the footwear or tire tread impression of sufficient nature to allow an expert to make a comparison against a known shoe or tire.
- L. Post a 1000-word synopsis of your findings and experience under the thread provided for Lab 4
Introduction
Brief statement that describes the experiment. One to two sentences is sufficient.
Methodology
Materials: List all of the materials and equipment that you used. Be specific – do not cut & past the generic list of items needed for the labs! For example, 99% Isopropyl Alcohol, 1 blue BIC Ultra Round Stick Grip ball point pen, 1 blue Zebra F-301 ball point pen, etc.
Procedure: This section tells exactly what you did. Don’t cut & paste the instructions that I provided! Be specific – provide enough detail for replication. The procedure you used affects the results. So, it is important to be accurate when describing what you did. This section is written in past tense and in paragraph form. Subheadings can be used if more than one experiment is conducted.
Results
Describe the outcomes. Be specific – tell exactly what you observed and what happened when you did the lab. You can insert pictures to illustrate what you are describing. Do not include opinions, discussion, or comments about the results. This section is written in past tense and in paragraph form. Subheadings can be used if more than one experiment is conducted.
Discussion
Explain your observations and discuss your findings. Draw conclusions from your results. If the same experiment was completed more than once, then compare the results. What do you think caused the results to differ? Discuss any limitations that you encountered. What recommendations do you have for future experiments? Again, be specific. This section is written in past tense and in paragraph form.
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