APPLICATIONS DEVELOPING BLACK & WHITE FILMS
Pull processing is a technique that compensates for overexposed film by under- developing it at the processing stage; thus it is the opposite of push processing.
Pull processing is most commonly used to compensate for accidental overexposure of a film; for example if a roll of ISO 125 film has been exposed with the camera set to ISO 50, pull processing can be used in an attempt to minimise the damage. It is only of use if the complete roll of film has been overexposed in this manner. In general, the technique is not to be recommended as there are rarely advantages in exposing a film at a slower speed rating than normal and the resultant negatives are difficult to print well. A minor exception is that it is sometimes possible to make negatives exposed in brilliant sunlight easier to print by overexposing the film half a stop or so, and cutting development by about 20%.
Certain developers, such as ILFORD Perceptol, are designed to produce a fine-grain result with some loss of film speed. This is not normally regarded as pull processing, but it is best to use a developer such as this in the case of inadvertent overexposure of a film. The fact sheets for individual ILFORD films or the ILFORD Film Processing Chart gives guidelines with this developer for accidental overexposure. It is only necessary to change the developing times, not the fix or wash times.
Pull processing is not necessary with ILFORD XP2 SUPER film which has great exposure latitude and can be exposed over a wide EI range with normal C41 chromogenic processing.