[pure-silver] Re: under-developed?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 19 Feb 2007 11:42:38 -0800
----- Original Message -----
From: "Agnes" <frcontrone@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, February 19, 2007 10:58 AM
Subject: [pure-silver] Re: under-developed?
It could be the difference with me and how I was taught.
The D-76 was taught to me in a college class. There the
only temp control was on the developer itself. But we
also had a development chart for the various temps, and
film types that was a good 20 years out of date. What
ever the temp of the water coming out of the faucet was
the stop, which varied widely depending on the season.
The fix kept in 5 gal. containers was changed out maybe
once a year. There were hundreds of rolls developed per
week. We just got so we would fix longer to get rid of
the pinkish color to our negs. It was there that I
switched to HC-110 after taking a Bruce Barnbaum workshop.
I also got my development times of digital truth froim
that point on. The grain was significantly smaller, the
contrast improved. No more weird things happening to my
negs. I use dilution b unless like you the times get to
close to 5 minutes. I like longer development times. I
also started bringing my own fix
to the school as well. I doubt the fix was the culprit in
why I disliked D-76. I just was never able to control the
contrast the way I wanted to with it.
Aggie
It sounds like the real difference was going to a
controlled processing environment from one with quite
uncertain materials and techniques.
Contrast is a function of the degree of development.
HC-110 and D-76 will produce nearly identical negatives when
used correctly. There are small differences in the
characteristic curves but they show up mostly at the very
high density end. HC-110 is a very well designed developer,
it performs well with many films, is long lived, and is
relatively easy to use. However, its not the optimum
developer for any film. By optimum I mean a developer which
delivers highest speed, finest grain, best sharpness, etc.
The differences will not be large but exist. HC-110 is also
very versitile because it can be varied in strength to
obtain convenient development times without affecting its
other properties too much.
D-76 was one of the first photographic developers worked
out with any understanding of the chemistry of development.
It was mainly the work of John G. Capstaff, of Kodak
Research Labs. The formula was originally announced in a
Kodak publication which also announced a new fine-grain film
for duplicating motion picture negatives published in 1927.
D-76 was found to be superior to the several formulas used
up till then for development of camera negatives that it was
rapidly adopted by the industry. It was soon discovered that
D-76 had the peculiar property of increasing activity with
time. This made predicting and controlling negative contrast
difficult. The Labs worked on the problem and came up with
an alternative formula for D-76 which included a buffer to
maintain the pH constant. Current packaged D-76 follows this
formula and is very stable in storage. D-76 became the
benchmark developer and remains so because it delivers close
to the maximum film speed, close to minimum grain and has
other desirable characteristics. HC-110 was intended to
provide a developer of similar characteristics in the form
of a concentrate.
Many developers devised in recent years make use of a
developing agent (reducing agent to be correct) which was
not available until about 1950. That is Phenidone. Although
Phenidone is not listed in the MSDS for HC-110 it is the
primary developing agent. Although many Phenidone containing
developers deliver higher speed than conventional
Metol-Hydroquinone types (like D-76) HC-110 is an exception.
It delivers speeds comparable or slightly less than D-76.
This is probably of no significance in actual practice
although HC-110 is not a good "pushing" developer.
If one is getting good results with HC-110 there is no
reason to change to something else. The problem of measuring
small amounts of concentrate can be handled in a couple of
ways including making up a small amount of a lower
concentration stock which is then further diluted for the
working solution.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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