[rollei_list] Re: OT Pyro & other developers WAS:Rollei Retro Film
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Tue, 26 Feb 2008 12:56:40 -0800
----- Original Message -----
From: "Jeff Kelley" <jlkphoto@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Tuesday, February 26, 2008 9:37 AM
Subject: [rollei_list] Re: OT Pyro & other developers
WAS:Rollei Retro Film
> Richard, thanks for the detailed info. You wrote "All
> ancient history" in
> your reply but there has been somewhat of a revival of
> interest in B&W and
> various newer formulae, especially Pyro variations.
> For example, 510-Pyro from Jay DeFehr gets rave reviews
> from most users:
> ascorbic acid 5g
> pyrogallol 10g
> phenidone .25g
> Triethanolamine 100ml
>
> The concentrate apparently has near infinite shelf life
> vs. other Pyro
> developers. The above concentrate is mixed 1:100 with
> water for a one-shot
> staining developer.
>
> I've mixed up a batch but have not had a chance to try it
> yet.
> Jeff
>
> On Mon, Feb 25, 2008 at 11:22 PM, Richard Knoppow
> <dickburk@xxxxxxxxxxxxx>
> wrote:
A curious formua with three reducing agents. There are
older formulas which combine Pyro and Metol. In these the
Metol is more a preservative for the pyro than an active
developing agent. Perhaps the same thing is happening here
but I wonder what the pyro is supposed to do since Phenidone
and ascorbic acid form a perfectly effective developer by
themselves.
One reason pyro had a bad reputation in the old days was
the instability of some of the formulas. In particular it
was common to alkalize using ammonia. Ammonia is volitile so
the strength of the formula would change day by day. Another
problem, and one faced by the movie industry after the
introduction of sound, was that pyro negatives with a stain
image are very difficult to analyse and control using a
densitometer. The densitometer must respond _exactly_ as the
print film does. The introduction of photographic sound to
movies caused a revolution in laboratory methods because the
sound must be printed onto the same film as the picture and
requires very much closer control if the distortion is to be
minimized. Before sound camera negatives were often
developed by inspection and one was at the mercy of the lab
man to get good results. The requirements of sound printing
and the change to panchromatic film (necessitated by a
change in the kind of lighting equipment needed for silence
on the set) changed all this and resulted in the wide
application of sensitometry and automatic processing. Stain
images could not be made predictably so negative development
went from the traditional pyro to M-H developers like D-76.
With the increase in availability of good M-H formulas and
tons of research being done on it the traditional pyro
developers fell by the wayside although they remain
favorites to this day.
It would be interesting to compare some of the new pyro
developers to traditional ones like Kodak D-1 or D-7
(pyro-metol).
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
Rollei List
- Post to rollei_list@xxxxxxxxxxxxx
- Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe'
in the subject field OR by logging into www.freelists.org
- Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with
'unsubscribe' in the subject field OR by logging into www.freelists.org
- Online, searchable archives are available at
//www.freelists.org/archives/rollei_list
Other related posts:
