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How long do you presoak?

There are three reasons for presoaking:
  1. Get the emulsion thoroughly saturated
  2. Ensuring even development
  3. For color film, bring the film and emulsion to the development temperature.
 
Sirius Glass said:
There are three reasons for presoaking:
  1. Get the emulsion thoroughly saturated
  2. Ensuring even development
  3. For color film, bring the film and emulsion to the development temperature.
Click to expand...

  1. Nowhere in any film manufacturers datasheets does it say film must thouroughly saturated before development. In fact Ilford say the opposite
  2. Even film development doesn't require pre-soak. See 1 above.
  3. Jobo ATL1500 only uses pre-soak for B+W film in its default programs and not for C41.
 
Sirius Glass said:
There are three reasons for presoaking:
  1. Get the emulsion thoroughly saturated
  2. Ensuring even development
  3. For color film, bring the film and emulsion to the development temperature.
Click to expand...


I said that those were the reasons. C-41 processing on the Jobo processor recommends presoaking, however Jobo specifically says not to presoak for XTOL processing and for replenished XTOL processing.
 
Sirius Glass said:
I said that those were the reasons. C-41 processing on the Jobo processor recommends presoaking, however Jobo specifically says not to presoak for XTOL processing and for replenished XTOL processing.
Click to expand...

depends which jobo processor. It's requirement of the processor to mitigate how the processor treats the film and not a requirement of the film itself. I just want to get that point across so that people using inversion or dip and dunk tanks don't think its a requirement of the film itself.
 
I was referring to the Jobo CPA, CPA2, CPP, CPP2, CPP2+ et al
 
I presoak for three minutes in the ATL-3. I develop 120 in an inversion tank and I do not presoak for that.
 

Matt,

Interesting! I also use my pre-soak time to get into the rhythm of agitating, etc., before putting the film in the developer, especially when I have tricky number of sheets in one batch.


Of course, we who incorporate a pre-soak into our routine have adjusted (tested) our development times accordingly. For the reasons you state, development will take longer starting with a water-saturated emulsion than without.

While a pre-soak is not necessary per se, if we do use one, for whatever reason (i.e., keeping the sheets from sticking together in the developer when tray developing), then making sure the emulsion is completely saturated before the film hits the developer seems logical to prevent possible differential absorption/diffusion of the developer by/into the emulsion. There must be data on that somewhere, but I can't seem to find it. Three minutes seems to work for the films I use.

If, and it's a big if, pre-soaked films when completely developed have more surface development than deep development when compared to film developed without a pre-soak, then that should (theoretically) help acutance some... I kind of doubt that this is the case, however. Much more likely is that developer onset is delayed a bit but compensated for by extending the time (assuming equal CI of films developed with and without a pre-soak).

Oh yes; I omitted one important reason for a pre-soak in my previous post: bringing all the tanks, etc. to the correct processing temperature. This, I believe, is why Jobo recommends a soak.

Best,

Doremus
 
Its interesting that Ilford has wetting agent incorporated in the films ...

Coz I presoak for 4 mins with 0.2ml of PhotoFlo per 300ml of the distilled water ...

I reckon the PhotoFlo helps remove finger grease and haven't had a failure yet ...
 

I used to presoak for 1 minute. I don't presoak any more because my development times are fine. You want to make sure the emulsion is all all swollen with water so the initial developer action slows somewhat. This will increase your development times which may be handy if you are nearing the 4 minute mark.
 
Although I never pre-soak black & white film, I can understand the reason for pre-soaking colour film, where process temperatures are so critical.
 
I have problems with Ilford films when I pre soak. I pre soak everything else for 2 minutes. My films are 120 4x5 and 8x10.
 
I only presoak TMY-2 and Rollei IR films when using BTZS tubes. Helps remove that pesky blue dye. Three minutes then slip them directly into the tube. The only time I presoak other films such as HP5 or FP4, is when I am giving them two-bath development in pyrocat-hd.
 
I presoak for five minutes before stand developing.
For regular development times, I do not.
 
cliveh said:
Although I never pre-soak black & white film, I can understand the reason for pre-soaking colour film, where process temperatures are so critical.
Click to expand...

+1
 
cliveh said:
May I ask why you presoak 120, but not 35mm? Not that I have ever presoaked a film, but why should the format size change your MO?
Click to expand...

I presoak 120 only. For 40 years I didn't have any unevenness with 35mm (Jobo inversion tank) but 10 years (maybe longer) ago I ventured into 120 and found that I had some discs of slightly reduced density: not full-blown airbells and visible only in clear blue sky. These were about 3mm in diameter on an 8x10 print. I was meticulous (I thought) in ensuring initial agitation etc, but it still happened.

Then I did a few minutes presoak. The problem went away never to return. FWIW, the film was Neopan400 and the developers were various Sandy King pyrocatechol developers (PMC to begin with then Pyrocat variants).

Why only 120? I don't know, but my results speak for themselves.
 
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