1. Refer to the "241-D300 Impressions - Footwear and Tire Tread Procedures Manual" on Blackboard. This was taken from the Virginia Department of Forensic Science, whom has all their SOPs available online. Devise a procedure for casting an impression using one of the techniques the document describes. What QA/QC measures do they take when casting an impression?

The 241-D300 Impressions - Footwear and Tire Tread Procedures Manual , published by the Virginia Department of Forensic Science, describes a rigid casting procedure to lift impressions. To be specific, this manual states that a "dental stone can be used to lift impressions such as mud and tire residues from surfaces such as concrete and tile" (VirginiaDepartment of Forensic Science, 2022). The following devised procedure should be used for this technique:

1. Prepare the impression for casting. If the impression is fragile, apply a fixative. Use excessive care when applying the fixative to avoid damaging the impression. If the cast is being made on dense soils, apply a release agent. Again, excessive care should be used when applying the release agent in order to prevent the impression from being destroyed.

1. Add the proper amount of water to the pre-measured amount of dental stone. The amount of water that is needed depends on the dental stone product.

1. Mix the mixture continuously for about 5 minutes so that the water can be fully absorbed into the product.
2. Carefully pour the casting mixture around the outside border of the impression and direct the flow into the impression. Make sure the impression is filled completely and evenly. There should be sufficient thickness to avoid the impression from breaking.