(a) film mottle: due to the use of

(a) film mottle: due to the use of stale film; (b) radiation fogging: occurs when the film is stored too near a source of radiation, or when a film is inadvertently left in the exposure room during the exposure of another film; (c) light fog: caused by storage of film in a faulty storage box or bin; leaving the lid off the box; exposure to white light in a faulty darkroom or to the use of the wrong type of safelight or too strong a bulb in the safelight, or to the use of a faulty film holder; it is usually local but may be overall fog; (d) pressure markings: due to clumsy handling of the film when loading or unloading the cassette or film holder; they are often in the shape of dark or light crescents: if dark, they are caused by local pressure or bending the film after exposure; if light, local pressure before exposure;(e) scratch marks: usually caused by a fingernail or abrasive material;(f) static fog: has the appearance of branched and jagged fine lines; it is due to electric discharges on the surface of the emulsion when the film is removed rapidly from a tight wrapper (very rare);(g) high or low density fingerprints: caused when handling the film with greasy or chemically-stained fingers;(h) low density patches or smears: due to splashes of water or fixing solution on the film;(i) dark patches or smears: due to splashes of developer on the film;(j) radioactive spotting: occurs as very intense black spots, often with a halo around them; caused by radioactive contamination of the wrapping paper (now very rare);(k) light spots: dust particles between the film and intensifying screens.