The two basic methods employed by police are photography and casting. In photographic preservation, technicians use oblique lighting to capture the shadows created by illuminating the impression at different angles. Photographers may also use spray paint or fingerprint powder on the impression to increase the contrast and definition. To make the cast more easy to photograph, it should be cleaned of foreign material and dried; the cast should also be photographed with a scale in the field of view. Certain techniques can be used to enhance contrast on footwear impression casts. After the photography, gelatin lifters or residue footprint lifters can be used to pick up the impression from the cast. These lifts can be preserved on transparent material or white pieces of paper. Snowprint wax presents another accurate method of casting snow impressions. 2 references