With unprocessed film, the density goes up as it is wrapped onto a spool, such that about 2 or 3 layers block all light, but loading instructions do specify "dim light" or "away from direct sunlight", and the loading assumes that the edges are completely protected. See a spool of 8mm film for an example.

After development, film has the density that results from the effects of: exposure + sliver halide quantity coated + development + the form the developed silver takes when developed. The maximum density is usually about 3.0 but is rarely used.