Once at the museum, the plaster jackets are removed and the matrix further excavated. This is a time-consuming and meticulous process. The actual fossil bone material is brittle, so the preparator must take care not to chip or fracture the underlying bone.

Next, the matrix is cleaned off the actual fossil bone.

If brittle, the fossil is saturated with Vinac (vinyl acetate), a shellac-like binding material that makes the bone surface more stable and less susceptible to fracture. It also fills in and glues together cracks in the brittle fossil bone.

Once the bone is exposed to the extent desired, a latex mold is made. The latex is brushed on in thin layers and built up. It is reinforced with burlap for strength. Each layer takes several hours to dry.

Next a cast is made. The cast is then painted to reflect the actual color of the fossil bone.