35mm film sometimes doesn't contain anti halation dye, but a tinted film base instead. 4x5" base is often clear, with anti halation dye on the back side of the base. If 35mm film were made this way, there's a high probability of scraping some of the dye off inside the camera.
35mm - no dye,
120 - dye (protected by backing paper)
220 - no dye (at least sometimes)
sheet - dye.