Making a Mold Star 16 Forensics Impression Mold


This mold making tutorial video demonstrates how Mold Star 16 FAST silicone can be used to take forensic impression evidence. Using Mold Star to mold footprints, tire tread, tool marks, etc. from a variety of surfaces creates a reusable mold that can be used to cast multiple positive reproductions in resin. Convenient cartridge dispensing reduces the time it takes on site to capture an impression to under an hour.

How to Make the Mold (0:16)
Mold Star 16 FAST is pre-packaged in 400mL cartridges. A mold box is placed over tire treads to contain the silicone and then secured in place. Top of the cartridge is removed and a static mixer is attached. The cartridge is the inserted into a dispensing gun. Silicone rubber is dispensed and allowed to flow over the tread impression. Cartridges are replaced as needed. The mold box is filled until the entire impression is covered in silicone. This example used five cartridges. Rubber is left to cure for 30 minutes before removing the mold box. The mold is then separated from the surface, reflecting the tread impression in perfect detail. Dirt and debris are washed away from the mold, and the mold is allowed to dry for one hour before casting.

How to Cast the Impression (2:01)
Smooth-Cast 320 is a very low viscosity liquid plastic mixed 1A:1B by volume. Place the mold onto a plastic sheet. Insert the mold and plastic sheet into the mold box. The plastic sheet will contain the liquid plastic within the mold box. Shake Parts A & B of Smooth-Cast 320 well before dispensing. Dispense equal amounts by volume and then combine in a mixing container. Thoroughly mix Parts A & B together. Pour Smooth-Cast 320 and allow to flow over the mold about 3/8 inches above the highest point of the impression. Smooth-Cast 320 cures in approximately 10 minutes. Allow the casting to cool to room temperature before handling. Remove plastic wrap from the sides of the frame and then remove the frame. Remove the plastic wrap from the mold. Pull off any excess plastic, then separate the mold from the plastic casting. Casting reflects perfect detail from the mold.