In my original question I asked "so what's the consensus opinion"? and so far we are all over the map on presoaking and except for photoflo in Dektol no real known problems there.
This is just about what I have found in reading old threads. It doesn't seem as if any real testing has been done or else there are so many differences in everyone's proceedures that it is hard to pin down. It would seem that you would have to be mixing your wetting agent pretty rich to have significant carry over on unrinsed reels.
The Ilford recommendations are intriguing though as there is so much evidence that presoaking is helpful or at the least harmless.
Les - Can you remember more about that photographer that had streaking problems caused by presoaking.
Just for the record I presoak with plain water just because I often use large tanks (1000ml stainless) and am concerned about the 30+ seconds for the chemical pour. I just do it habitually to be consistent even with small tanks. I really should do some testing.
I seem to recall that Ilford stated that they had put photoflo into the emultion and if you presoaked you could/would wash it out. With PMK, I add some photoflo so the film won't stick together. I don't see any reason to change after a lifetime of presoak.
One more data point for BobF - I don't presoak my negatives since the b&w films I use (TMY, Delta 400) don't need it.
I remember the Ilford proscription against pre-soaking - "streaking" was not the concern - Ilford claimed that presoaking caused an unfavorable "swelling" of the emulsion prior to contact with the developer and the end result was a decrease in overall image quality, especially in acutance.
I might be remembering incorrectly (sadly, it does happen at times) but I think I read much the same thing in a report from Agfa, and from one or two of the color chemical manufacturers.
Anyway - I don't prewet/ presoak.
I presoak larger formats because I believe it causes the developer to enter the emulsion at a controlled rate while replacing the water put there by presoaking. I agitate during proesaok - I also like the antihalation layer out of the mix. I also agitate by rapidly inverting the tank back and forth and then a radial spin before clunking it down to knock out air for each 5 second agitation. I wonder if gentle agitation interupts the laminar flow of chemical and if it replenishes exhausted developer as well. I have never had streaking or problems doing this. The effect of presoak on accutance is an interesting idea. It would be interesting to try some identical sheets and if the difference could be detected. - Frank
The problem that comes about with photo flo contaminated reels is that the reels do not allow the bubbles to escape and trap them against the films surface. With sheet film this is not necessarly a problem.
[ Les - Can you remember more about that photographer that had streaking problems caused by presoaking.
The photographer was a lady called Fay Godwin and the problem was streaking in even toned areas such as skies. At on point she had a sizeable number of undeveloped films that she would not process until the problem had been sorted. The final analysis was the the pre soak water was removing something when it was poured away so Fay went through the labourious process of pouring the pre soak water into a graduate containing the undiluted developer and refilling the tank with it. The main thing was that it eliminated the problem.
Ed mentioned a similar problem with Agfa, I can verify that for John Davies another British photographer told me that he used Agfa 100 and had the same problem for a while and solved it in the same way as Fay.
It was about 15 years ago that this happened .
[quote="Les McLean .....so Fay went through the labourious process of pouring the pre soak water into a graduate containing the undiluted developer and refilling the tank with it. .....[/quote]
She must have been very convinced that presoaking was benificial to go through that much of a PITA. Thanks for the info Les. I was planning some test negatives (for lots of other reasons also) and will make sure to include some blah sky.
BTW everyone, I filled a two reel SS tank with an over rich Photoflo mix (half cap in 500ml) then drained it and let it dry. I then filled with water and shook vigorously to see if it foamed from residual Photoflo. NONE ! I can not see how Photoflo carryover could ever be a problem unless plastic reels and tanks are a lot different. Someone ought to try this with plastic.
You don't need to put your photoflo in the tank. I use a small jug. I take the film off the reel soak it. Then with a gloved pair of fingers I wipe it. Repeat for each roll. If you're only doing two rolls it's not going to take much longer. The little jug I use is big enough to handle anything up to 4x5.
I'm not sure how valid your test for carry over is. Doesn't matter if you can tell if it's there but if it reacts with the next batch of film. Used to be you didn't wash beer glasses with soap because the faint traces that remained in clean glasses would kill the head.