We were taught to prewash the film with water before agitating with developer. Then I hear from others that we don't need to do the prewash. I'd like to hear from others who have been at this a lot longer. We use Ilford black & white, primarily Delta 3200 and HP Plus 400.
Thanks to everyone for their thoughts. This site has been very helpful!
I think you'll get as many different opinions on this as there are photographers...
Following advice from DF Cardwell on this site I no longer use a prewash with Rodinal developer. I have seen no adverse effects from this.
I do use it with XTOL developer, but have not done any tests to see if not doing a prewash will give me less-than-stellar results. It's an old habit in my case.
With a pre-wash, you decrease the risk of uneven development, especially with developers and dilutions that require short development time.
Don't forget that with a pre-wash, you have to increase development time for about 20 seconds (the time that water in the emulsion need to dilute in the developer).
A 2 bath developer is a developer in two parts, a bath A and a bath B. Examples are Diafine and split D23. In the first bath not much development takes place but the fil is given time to soak up chems that are activated by bath B. This kind of developer has some advantages since time and temperature are not critical and it keeps a very long time. Diafine also gives a one stop push to many films.
Ilford documentation recommends no pre-wash with their films. I take the view that they probably know more than anyone else on the subject so do not pre-wash...