Pulling and pushing film are darkroom techniques for exposing film at an ISO different from its nominal box speed and compensating in development. Pushing means rating the film higher than its box speed (underexposing) and then developing for longer than standard time to bring shadow detail back; pulling means rating it lower (overexposing) and developing shorter than standard time to reduce overexposure. The technique gives a photographer the ability to adapt a single emulsion to a wider range of light conditions than its box speed alone would suggest.
The classic example is Kodak Tri-X 400 pushed to 1600. The photographer shoots as if the film were ISO 1600 (two stops under-exposing it), then develops for roughly twice the normal time in a developer like Kodak D-76 or HC-110, often diluted differently from standard. Shadow detail remains compressed (you cannot truly create exposure that was never there), but mid-tones and highlights pull up to printable density, and the resulting negatives carry a distinct visual signature: heightened contrast, larger and more prominent grain, slightly compressed tonal range, and a punchy, gritty character that has defined photojournalism and street photography for decades.
Pulling is the inverse and rarer operation. A photographer might rate Tri-X at 200 and develop shorter to handle a high-contrast scene whose extreme highlights would otherwise blow out. Pulling reduces contrast and tames grain, useful for studio portraits, contrasty backlit subjects, or matching shooting conditions to a softer aesthetic. Many landscape film photographers use a one-stop pull to extend the apparent dynamic range of their film.
The choice of developer matters as much as the time. Microphen, T-Max Developer, and Ilford DD-X are formulated to handle push processing with finer grain than standard developers. Diafine, a two-bath developer, is widely used for push processing because shadow density depends less on time. Color film pushes are more constrained: C-41 and E-6 processes were standardized for box speed, and pushing typically introduces color shifts that monochrome can avoid.
Pushing is a powerful tool but not free. Each stop of push raises grain noticeably, deepens contrast, blocks up shadows further, and compresses the tonal scale toward the higher densities. Two stops is the workable range for most films; three stops moves into experimental territory where shadow detail is largely absent. The photographer should commit to the push for the entire roll, since development affects every frame equally, which is why working film shooters often carry multiple bodies loaded with different speeds for variable conditions.
Digital has largely subsumed the practical need for pushing, since raising ISO on a digital sensor is equivalent in concept and instant in execution. But the aesthetic of pushed film, that specific combination of grain, contrast, and tonal punch, remains a recognizable signature, and contemporary film shooters continue to push deliberately for the look, not the necessity. Labs offer push and pull processing as standard options on the order form.