Pre-Wash

138S · Dec 6, 2020

Vaughn said:
Just plain no. Once the film is wet, it is wet. All chemicals will react evenly when introduced to an evenly wet emulsion.

We have to explain a phenomena, a too short pre-wash ends in an uneven development...

Observations are next, at least with ilford film:

1) No pre-wash = Even Development

2) Short pre-wash = Uneven Development (or risk of, at least if agitation not continuous)

3) Long Pre-wash = Even Development

What is the difference between 2 and 3 situations ? IMO both have the film wet and surfactants washed and single difference is gelatin swelling... anything else?

The question is, wow do we explain that a Short pre-wash may deliver uneveness?

Sirius Glass · Dec 6, 2020

138S said:
How do we explain that a Short pre-wash may deliver uneveness?

I do not and I will not waste my time attempting to. I use a five minute prewash time for all my Jobo processing. Tinsley https://www.amazon.com/Rotary-Processor-Manual-John-Tinsley/dp/0902979116 recommends five minute prewet for all films except Kodak Tri-X in XTOL and Kodak agrees with his findings. Using five minute prewet with Ilford films, roll and sheet film, and Rollei IR 400 eliminates air bells and streaking. I have been using prewet of over ten years and never had a problem.

BrianShaw · Dec 6, 2020

So, Steve... are you asserting that your 5-minute pre-wash is in theCategory 3 “long pre-wash” category and that’s why it works for you? Seems so to me.

MattKing · Dec 6, 2020

FWIW, here is what Simon Galley, then one of Harman's directors, said in 2015 about pre-soak and black and white film development:
[URL="https://www.photrio.com/forum/threads/pre-rinse-or-no-pre-rinse.125702/#post-1662694"]Pre-rinse or no pre-rinse[/URL]
"We do not believe a pre-soak is necessary with any of our film emulsions, but nor do we believe they are harmful unless it is grossly extended"
and
"I would take the good advice given by others in this thread, if it works for you one way or another... fine, if its part of your workflow and you have no issues one way or the other... again fine... we are not prescriptive to experienced photographers and processors, same as with 'recommended' dev times".
"Simon ILFORD Photo / HARMAN technology Limited :
From my personal perspective"

Sirius Glass · Dec 6, 2020

Sirius Glass said:
I do not and I will not waste my time attempting to. I use a five minute prewash time for all my Jobo processing. Tinsley https://www.amazon.com/Rotary-Processor-Manual-John-Tinsley/dp/0902979116 recommends five minute prewet for all films except Kodak Tri-X in XTOL and Kodak agrees with his findings. Using five minute prewet with Ilford films, roll and sheet film, and Rollei IR 400 eliminates air bells and streaking. I have been using prewet of over ten years and never had a problem.

BrianShaw said:
So, Steve... are you asserting that your 5-minute pre-wash is in theCategory 3 “long pre-wash” category and that’s why it works for you? Seems so to me.

Yes.

BrianShaw · Dec 6, 2020

138S said:
The question is, wow do we explain that a Short pre-wash may deliver uneveness?

... so the question remains unaddressed...

Vaughn · Dec 6, 2020

The same way we explain that a Short fixing time may deliver uneven fixing.

(PS -- do it for the proper amount of time, but don't skip the fix just because doing it for a Short time can give bad results).

NB23 · Dec 6, 2020

BrianShaw said:
... so the question remains unaddressed...

Because you have to fully fill the sponge that is also known as the emulsion.

The emulsion has to be fully filled with water, and this takes some time. If it is not fully filled with water, the developer will start developing the less filled spots, first. The developing action will not be uniform among the whole surface.

You can end up with a pattern similar to clouds in the sky.

NB23 · Dec 6, 2020

This is also exactly why an acidic stop bath is important, as opposed to water.

Water will have to take the place of the developer inside the sponge, and while it replaces the developer, this takes time. And during that time, there are spots still developing at a different pace. This makes for even more unevenness. And then you will FIX the unevenness!!

For a water to finally act as a stop, it has to last long. An acidic stop bath makes it short and sweet and leaves not enough time for the developer to create unevenness.

BrianShaw · Dec 6, 2020

138S · Dec 6, 2020

Sirius Glass said:
I do not and I will not waste my time attempting to. I use a five minute prewash time for all my Jobo processing. Tinsley https://www.amazon.com/Rotary-Processor-Manual-John-Tinsley/dp/0902979116 recommends five minute prewet for all films except Kodak Tri-X in XTOL and Kodak agrees with his findings. Using five minute prewet with Ilford films, roll and sheet film, and Rollei IR 400 eliminates air bells and streaking. I have been using prewet of over ten years and never had a problem.

Personally, in the last 10 years, I never had streaking or uneven development I never had a problem of streaking of uneveness, and I never make a prewetting, I use Kodak, Fuji, Foma and Adox BW films, with other brands I can't tell much...

Sirius Glass said:
Tinsley

Instead The Darkroom Cookbook says:

PRESOAKING FILM
There is absolutely nothing wrong with presoaking film prior to development—it just isn’t necessary in most cases.

Presoaking is necessary and should always be used for the following:

● Tray development of multiple sheets of large-format fi lm using the shuffl e method.
● With development times less than five minutes. Presoaking will ensure the complete removal of the anti-halation backing with short development times
● With stand development
● When a specifi c process calls for presoaking.

__

Also ilford advices in all datasheets to not use prewetting... but they admit that a long enough prewetting won't harm the film. Officially kodak only recommends Prewetting for developing sheets in trays with the shuffle method.

NB23 said:
This is also exactly why an acidic stop bath is important, as opposed to water.
Water will have to take the place of the developer inside the sponge, and while it replaces the developer, this takes time. And during that time, there are spots still developing at a different pace. This makes for even more unevenness. And then you will FIX the unevenness!!
For a water to finally act as a stop, it has to last long. An acidic stop bath makes it short and sweet and leaves not enough time for the developer to create unevenness.

Water stop bath won't cause any uneveness in the development, I mostly use water stop and I had not a single uneveness in the development in the 10 years, since I returned to film, I mostly have processed Ilford, Kodak, Fuji, Foma and Adox BW films, with other brands I can't tell...

138S · Dec 6, 2020

Vaughn said:
The same way we explain that a Short fixing time may deliver uneven fixing.

IMO it is not the same case. Fixing is not completed uniformly as some areas have more halide to remove than others, and also the size of halide cristals vary being larger in the less exposed areas, fixing is made to completion... Even in the case fixer reaches all areas uniformly the more exposed areas are faster to fix.

Instead, the case of development uneveness has other governing variables, related to a non uniform developing action.

NB23 · Dec 6, 2020

Ok. From now on I will always pre-soak. Use water stop bath. And probably stand-develop as well. Always.

Same for printing. I will, from now on, pre-wet my papers before they enter the developer, in which they will stand develop for a whole hour. Water stop, stand fix and then a quick wash.

All-in.

I’m going to make developing film and printing a 20 hour messy Hell instead of a clean few minutes for developing film and a few hours of clean, civilized darkroom work.

Wallendo · Dec 6, 2020

I once obtained a bulk roll of Panatomic-X in a bulk loader I bought on eBay. I knew nothing else about the film. There were a number of artifacts on the film, but I found that presoaking did greatly reduce the number. I just used tap water.
I also presoak Fomapan 100 in 120 format so that my stop bath doesn't end up turning green.

BrianShaw · Dec 6, 2020

Post 63: That’s hilarious!

138S · Dec 7, 2020

NB23 said:
Ok. From now on I will always pre-soak. Use water stop bath. And probably stand-develop as well. Always.
Same for printing. I will, from now on, pre-wet my papers before they enter the developer, in which they will stand develop for a whole hour. Water stop, stand fix and then a quick wash.
...

NB23, The way you tell may work perfectly, of course, but please let me tell some considerations.

Both water stop and prewetting are controversial, we always can find a doctor or a priest that prescrives the drugs or the moral rules we want , so the same for the darkroom

Those are my thougts about your workflow:

> Prewetting IMO makes less sense for paper, as usually paper development is made to completion we don't have much risk of uneveness in the development, having an additional tray with water takes space, if having the space it would be worth using a double fixing bath which is extremly efficient and it delivers archival performance ...to not mention tonning trays !!!

> Me, I use water stop for film (no pre-wetting), but with paper a water stop (non acid) has more risks, specially if you want to open light as soon as possible to inspect the still wet print. A print has to be judged when dry, but you may want to see if it is flawed (or not excellent enough) as soon as possible.

> IMO, better to keep an open mind. "I will always do that from now..." is not the way to advance. Chemical photo has many nuances and complexities, and we have to try many ways to refine our workflow. Nothing wrong in using a well consolidated workflow after we have experimented a lot, but having the mind open can only be recommended. Test and test... to advance, then test again.

138S · Dec 7, 2020

llugguss said:
Prewash is important

Why ? For what is Prewashing important ? beyond those 4 particular cases mentioned by the Darkroom Cookbook...

Industrial labs and minilabs processed 930 million rolls in 2003 (peak production) with no prewash, roller transports dipped those 930 million rolls in C-41, E-6 or BW chem with no Prewash, and with absolutely no harm from not prewashing. If it was important then industry would have used it, a water bath is for free...

Personally I made side by side tests and I found no difference, have you tested it ? Still also I found no harm in prewashing 4 min TMX and HP5 before Xtol, the same result. So also no problem if prewashing long enough.

Pre-Wash

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