The Rosco 101034046020 Cinegel neutral density filter roll is designed to absorb excess light so that lighting can be balanced with it.
Cinegel color and correction filters are manufactured using Rosco's unique deep-dyed technique. This process begins with a 48" (1.2m) wide roll of clear PET polyester that is passed through a heated dye bath. The bath causes the film to swell, expanding the polymer structure and allowing the dye molecules to penetrate into the base film. As the polymer contracts to its normal form, the dye is trapped below the surface.