Make fresh footage look like it was shot on a roll left in a warm drawer for a decade. The color layers decay unevenly, the base fogs over, and patches of the emulsion age faster than others.
Degradation and crossover
Degradation is the master control; everything else scales with it, and 0% leaves the clip untouched. Crossover tints shadows and highlights in opposite directions, blended by brightness, so a face picks up magenta in its shadows while the bright background turns cool.
Base fog
Old film develops density even where no light reached it. Base Fog raises the black point by up to about 52 levels and rescales the tones above it, the washed, low-density look of a roll past its date.
Mottling and grain on video
Mottling modulates exposure and cast in soft patches, so some areas look further gone than others. The pattern stays fixed while the picture moves under it. Grain is redrawn on every frame, 30 times per second of source time, so it reads as moving film rather than a texture pasted on the clip.