Archived posting to the Leica Users Group, 2007/08/25

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Subject: [Leica] Pan F - Pyro First shot
From: cif at halcyon.com (Larry Bullis)
Date: Sat Aug 25 21:36:03 2007

I used to use pyro-acetone a lot.  Wall and Jordan (Photographic Facts 
and Formulas, a classic reference tome) said that it was useful for 
glass plates (specifically recommended it for lantern slides) but didn't 
recommend it for "modern" films.  The fact that their last edition (not 
including the later John S. Carroll edition - of which I couldn't figure 
what had changed from the previous) was published in 1947 might shed 
some light on what they meant by "modern".  I suspect that the acetone 
had a way of dissolving cellulose nitrate, but leaves current bases 
unscathed.  I have never had a problem with it.  Of course, some people 
might object to losing close to three stops something of a problem.  
Generally, I don't.  You could use Pan F or Tri X.  Maybe at the same 
ISO.  I wouldn't use Pan F with it.  I don't want to shoot at ISO 5, or 
even 7.  Where did the lost speed go?  Simple.  It transforms magically 
into really great shadow detail. 

When I processed sheet film in PA I either used a tray or processed it 
in the Merz processor, an internal drum in which the chemicals lay in 
the bottom as the drum rotated and rocked -sloshing around.  In both 
cases, there was a great deal of surface area per unit volume, meaning 
lots of aeration.  That resulted in a great deal of staining.  
Processing in a small tank did not produce as much stain.  I rather 
liked it both ways, actually, but there is a difference.  PA was 
incredibly useful and once saved my neck big time on a job, when I 
forgot that I was shooting Tri X in the M4 when I had my meter set for 
Kodachrome 64.  The result was stunning.  NO visible grain and the most 
gorgeous tones you ever saw.  Subject: shovel with foot pressing on it 
making hole in dirt.  It was a how-to sequence for a garden job.  ISO 64 
was just right for tri-x (non professional; I like the amateur emulsion 
a lot better anyway.  Besides, I could buy it in Friday Harbor WA, where 
no one had ever heard of Pan F). 

The point here is that you can have the stain you want.  Put a piece of 
exposed film end into a bit of it in a graduate containing your pyro 
developer; you can see the oxidation products stream off.  It oxidizes 
like mad, and that seems to make the stain happen.  Not enough stain?  
Rot the developer a bit.  Leave it on top of the water heater for 15 
minutes exposed to the air.  Throw a little acetone in it, that works, 
too, but it would change your development time.  Acetone, as I 
understand, reacts with the sodium sulphite to produce some sodium 
hydroxide.  If there is a chemist in the group, I wouldn't mind hearing 
more about it.  When you put acetone in it it feels slippery, which 
indicates a base.  I do know that if you put a bit of acetone in dektol, 
it makes a pretty good sheet film developer at about 1:9 and it feels 
slippery, just like it would if you mixed NaOH with water.  I'm real 
familiar with this because I also use Windisch pyrocatechin, which uses 
10% NaOH as the environmental variable.  OK it is toxic.  I wear 
gloves.  Just respect the chemicals. 

Personally, I think that the stain is over-rated somewhat.  On the other 
hand, one colleague for whom I used to process film called me a while 
back complaining that the negatives he processed himself didn't have 
that quality that he loved, as mine did.  Maybe not.  But I like the 
quality of those pyro negatives even when the stain is minimal.  I don't 
know what it is, exactly, but at best, when enough exposure is given, 
the shadow detail is incredible, only to be surpassed in the incredible 
sector by the amazing whites.  I found a fluorescent plastic Donald Duck 
on a beach once.  Unbelievable!