[1] The technique dates back to at least the 1880s,[2] and results in fine grain, increased perceived sharpness, and smooth tonality, but is time-intensive and runs the risk of producing certain processing defects.
This has the effect of spreading the developing fluid evenly over the surface of the film and preventing localised overdevelopment.
The process was popular in the late 19th and early 20th centuries, and was used by Eugene Atget[1] and William Mortensen,[3] among others.
It has a compensating effect in that the developer exhausts itself in areas which require greater development while remaining active in less-exposed areas, which has the effect of boosting shadow detail while preserving bright highlights.
[5] In the example to the right the developing fluid has filtered through the sprocket holes of a frame of 35mm film, producing streaks of overdevelopment that would have been masked with more agitation.