[pure-silver] Re: Film developer temperatures??
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 20 Mar 2005 14:32:33 -0800
----- Original Message -----
From: "David Swinnard" <davidswinnard@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, March 20, 2005 8:28 AM
Subject: [pure-silver] Film developer temperatures??
>I grew up using 20C (68F) as a standard temp. for film
>developing, and
> in my non-southern (NA centric view) location seldom had
> issues
> maintaining it, summer or winter. The cold water tap
> always delivers
> sub-20C water here. For unknown reasons, I started to
> wonder whether
> there are any significant benefits to using other (higher)
> temperatures.
> The only obvious one I can think of is shorter dev. times
> though I've
> not yet been rushed enough to pursue a higher temp. for
> that reason
> alone. (My previous reluctance to move chemical temps.
> beyond room (20C)
> temperature is dealt with by the JOBO CPA-2 now available
> to me.
> Sometimes it just makes a fine chemical-tempering unit
> rather than a
> developing system.)
>
> So, are there any compelling reasons to re-think my dev.
> temp.
> strategies? I seem to recall reading somewhere that
> Perceptol/Microdol-type formulations benefit from temps in
> the 24C (75F)
> range but can't remember the reasoning. What about other
> developers?
> Will I gain anything, beyond shorter dev. times? Are there
> implications
> for sharpness, grain, etc. with higher dev. temps?
> (keeping them in the
> realm of the reasonable)
>
> I frequently don't bother with the JOBO for a few rolls of
> film and use
> my old SS Nikor tank and reels. sheet film is always in
> the JOBO now.
>
> (In my darkroom, over the last few years, you would likely
> find devs.
> like my regularly used XTOL (1+3, never a problem had),
> FX-39 (when I
> can get it), Rollo-Pyro (from B+S), Perceptol (at 1+3) and
> even Pyrocat
> HD once. Films typically TMY or HP5 in sheet and Acros,
> TMX, Delta 100
> in 35mm/roll formats.)
>
> Just curious, Dave
>
68F became the standard temperature around the late
1930's. Before that it was 65F! The reason was simply to
prevent excessive swelling of the rather soft emulsions of
film and paper of the time. Color film is designed for
processing at 100F and much modern B&W film is made the same
way. I would check samples of unknown films to see if they
withstand higher processing temperatures but all should be
OK at 70F or even 75F. Processing times are shortened. Kodak
gives 75F as the preferred temperature for T-Max developers.
I don't know why. Higher temperatures than 68F are often
recommended for developers like Microdol-X, Perceptol, D-25,
mainly because they are very slow. D-25 BTW is a good hot
weather developer because it contains a lot of salts and is
about neutral pH, both of which tend to minimise emulsion
swelling. Its also slow so the increased temperature will
not result in excessively short developing times.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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