Topic: Prewash with rotary processing?

[DonkeyDave]

I was chatting with a 'pro' last week, he was wanting me to dev some 35mm film for him. I use a JOBO rotary processor for everything. Ilford recommends leaving out the prewash stage to avoid excess contrast from the constant agitation. So I've not prewashed for years, and been happy, I occasionally get faint uneven development on blank skys/fog but really only when scanned not easily visible on the negative. Nothing that cannot be worked around. I also tend to reduce development time by around 10% to get negatives that scan well, my scanner seems to prefer under to over development.
My mate was really surprised that I didn't prewash, he seemed to think it was pretty negligent verging on madness not to do so. Am I missing a trick here? I've got an old CPE2 if anyone else has experience with this.

[stevesegz]

Hi Dave,
I think this falls into the personal experience bracket. I always pre wash but have moved away from rotary processing apart from 8x10 due to uneven development with trays.

I cant remember why, but I have a feeling it was when I used alot of Foma films as I was doing as much as I could to remove the blue colouring of the film base and there did seem some logic in getting the film to the same temperature as the chemicals so there was a constant there.

So for me its been a case of find a constant that works and stick with that. That way you can vary one element, ie film/developer knowing your processes are consistent.

Just my 2p, somebody more techno minded may have more insight than I can offer.

[LT]

I find that it's an absolute necessity with 4x5 tank development, less so with 120 or 35mm. Otherwise uneven an streaky negs abound. And those streaky skies might manageable in digi processing, but put that neg in an enlarger, especially a condenser light source, and it will be a nightmare.

[Francois]

The goal of pre-washing is to make the emulsion swell before you get the developer in. That way, the developer penetrates the emulsion evenly.

Nowadays it's said to be less necessary but I still do it.

[KevinAllan]

There's a lot of threads on APUG and Flickr on this issue; as on most topics if you wait long enough to gather a big enough sample of replies, there will be an equal number of vociferous viewpoints at either extreme, and very few people sitting on the fence.

For what it's worth, when using my Jobo CPE2 with C41, I do prewash, for the simple reason that the instructions with the Digibase chemicals tell me too. Mind you, those instructions omit to mention the need for a rinse before and after fix, so they're not that good a source.

With b&w, I only prewash with TMax, to remove some of the stain.
 

[DaveP]

I have taken to prewashing E6 film to avoid some marks I was getting and it seems to ave done the trick. I also prewash FP4+ and Hp5+ without issue as they are pretty robust emulsions but I had problems of grain clumping on PanF which ilford have advised is down to the prewash, but I haven't shot any since to confirm if this is true.

[Aki]

With C-41 and E-6 I alway prewash per instruction.

With B&W, I prewash when I get streaks and uneven development.   Then I get lazy and start to omit prewash.  Sometimes I can keep skipping prewash.  Thrn I get some streaks or some such.   Then I start pre washing.  Then I get lazy and start to skip prewash…..   The loop continues.

[stevesegz]

I had problems of grain clumping on PanF which ilford have advised is down to the prewash

mmmm, interesting, I had some issues with Pan F, switched to Rodinal and everything was fine, time for a test.

[original_ann]

I've been using the JOBO Press Kit.  It has me do a pre-warm (rather than a pre-wash) for C41.  The Arista Rapid I use for my E6 has me do a pre-wash.  I'm going to have to go back and scrutinize my images - I can't recall streaks...

[DonkeyDave]

Thanks all, very interesting, I have a problem with uneven dev with C41 at times, mostly visible on 617 negs. The Fujihunt kit doesn't tell you to do a prewash, maybe I should try.
I was down in the woods again at dawn today and obviously got excited as I wasted 8 sheets. I've prewashed and then developed as normal. The negs look a little dense, so I might have to reduce the dev times further.