I always prewash with C-41, mostly to get the film and tank to the correct temperature.
I used to do that, but I've discovered that prewash makes harder to get the colors right, especially with Ektar. Since then I do not prewash any C-41 film.
I still prewash my E-6 films, because I didn't discover any ill effects of doing so.
I'll take the bait.. I don't.
I mostly don't because I trust the highly paid highly educated scientist and engineers of Kodak and Ilford.
I messed about with it long ago...
I think the bias of Kodak's information has always been more towards the commercial processing of film, not the cute little Paterson tank (or whatever). So getting a deep tank up to temperature before dunking a film in it isn't a normal part of the advice, it is taken as read the deep tank is already at 70F (or whatever). Ilford are now more geared in their advice towards the home user, but it wasn't always the case. But this is a circular discussion anyway, even if Ilford and Kodak said 'pre-soak your film' there would still be people going in the other direction and saying 'I don't see the point and I've never had a problem'.
kodak used to recommend ( ? 20 years ago ) to prewet films
but when xtol came out, they said " go right in the developer, no pre wet is necessary "
when i say kodak - i mean if you called with a question about film or developer
to the now defunct professional services division help-line ( 1800424-2424 i think was the number ) ..
maybe they fed us pros mis-information for all these years ... it wouldn't be the first time ...
they told me the wrong thing ... when it first came out, they had me using tmax developer ( not RS ) for sheet film
processing in a tank/hanger system and it nearly ruined 100 sheets of film .. with the dreaded green metallic fog.
i haven't a clue about jobo, never used their systems or have any idea what they suggest for
film processing ... i do have 4 little jobo plastic 1L chemical containers though, they are about 20 years old and still work great
Back in the day, in the 1980s, a Kodak rep specifically told me to presoak their films. When they introduced Tmax film he told me to increase the presoak from 30 seconds (with the older films) to 2 minutes with the Tmax films.
Presoaking lessens the chance of uneven development. Except I did find that with Agfa films it actually seemed to increase the chance of mottling.
Regarding tray processing sheet film, I would hate to try to do it without the presoak. Film sticking together in the developer is bad news.
I have never pre-washed a film and can't see the point. If anything, I would suggest that a pre-wash delays the ingress of developer into the emulsion and may effect development times.
That's precisely one of the reasons why Jobo recommends - or recommends for all but Xtol I guess - the pre-wash/pre-soak. It requires a slightly increased development time for the same contrast, and experiment has shown that this very closely approximates the otherwise required shorter time to compensate for the continuous agitation in rotary development. It's not essential by any means, nor precise, but it makes your developing times close enough that the same starting points as for inversion processing can be used and be very close to the mark.
Are you saying KODAK said don't pre-wet or JOBO? i don't think KODAK has changed their position but JOBO has.
I think John misunderstood the previous.
Jobo always said to pre-wet. Then when Xtol came out they released the document linked, or an earlier version of it I believe, and said NOT to do so with Xtol. Their recommendation with other developers is, AFAIK, unchanged.
I have some negatives I developed in the Jobo in Xtol years ago but I honestly can't recall if I pre-wet those or not. I haven't used Xtol since I got bitten several times by the bad small packages. I know, they fixed it (by doing away with the small size) but it left me badly burned enough to still have a bad taste.