One good reason for a pre-soak is to keep sheet film negatives from sticking to one another when developing them by hand in trays in batches. Anyone who has had the unpleasant experience of having two precious negs stick together in the developer knows what I mean. It can take an hour in the dark trying to soak them apart if it works at all. This, and avoiding air bells are the primary reasons why some photographers use a pre-soak. The differece is that it will add a little to your developing time. Some add 30 seconds or so to the time (or "ignore" the first 30 seconds of developing). Testing is better. In order not to have two developing times, one for the pre-soak, one for not, I simply pre-soak everything for one minute. If you are developing in tanks and have good, repeatable results and no air bell problems, you have no need of a pre-soak. Regards, ;^D)(posted 8851 days ago)