A pre soak is a preparatory step in photographic processing where film or photographic paper is immersed in water before the development stage. This helps to ensure even emulsion swelling, prevent streaks or uneven development, and improve the consistency of the final image.
Pre soaking is particularly important in certain colour processing methods, where precise chemical interaction is critical. By allowing the emulsion to absorb moisture uniformly, pre soaking contributes to more accurate colour reproduction, smoother tonal gradations, and overall higher-quality photographic results.