Rae Adams (rae.adams@gtri.gatech.edu)
Tue, 02 Mar 1999 18:05:11 -0400
>>>Having emulsion formulas isn't really all that useful, other than as a
>>>basis of comparison of what is in various types of emulsions and the ways
>>>of "constructing" some of them--in other words, as a learning experience
>>>and as a starting point only. Emulsion formulas are a whole lot like cake
>>>recipes: what works for one person under one set of parameters (altitude,
>>>oven temperature, type of flour, moisture content of ingredients, quality
>>>of shortening, expertise of the cook, etc) is a disaster for someone
>else.
>
>
>What are you talking about? A formula is a formula. But a procedure is
>also required. I have a formula/procedure for the manufacture of Matrix
>film, all materials are listed as are the specific steps required to create
>the emulsion and cost it. Follow it and it will work, if you do everything
>correctly.
>
>What is impossible for 99.999% of the people on this list would be the
>creation of a color film that exhibits any quality. Simple black and white
>formulas are simple, though.
>
>As for the Cooking analogy, I am not a cook, but I can read a cookbook, and
>there are no secrets. Do what it says and there should never be a problem.
>
>RM
Oh dear. I see that I have been greatly misinformed, and with such mistakes
on my part appearing in a public forum. I would apperciate your input on
this and am most anxious to correct my mistaken assumptions because I just
can't seem to reconcile your statements above with the numerous accounts in
the photographic literature to the contrary (and my personal experience,
not that this counts for anything--we can always assume ineptitude on my
part). Perhaps you can kindly explain to me why the major film
manufacturers had such a dificult time replicating the procedures and
formulas for gold sensitization that they found in the purloined German
literature. They spent a whole lot of money (and a whole lot of
person-hours) working this out. Surely it should have worked first-time
every-time when they used the same formulas and procedures. In addition, I
have read in the emulsion-making literature that in spite of great attempts
by many companies (and in spite of their having the formulas and
procedures) Agfa's Portriga paper was enormously difficult to match. We're
talking about the big industrial guys here. With big budgets. With
sophisticated labs. Or perhaps you could tell the big guys why sensitizing
with rhodium-ammonium chloride has been such a problem. On a more recent
note, when the company that made Zone VI's Brilliant paper went out of
business in France, a British company attempted to replicate the emulsion.
I called personnel at Zone Vi and at Calumet for a period of two years (or
more) checking on when a new emulsion would be ready. I understand from my
conversations with the aforementioned personnel that the new company went
through a trial and error process with the emulsion so that it would match
the original French paper. Why did they have to do this? They had the
formula, the procedures, the materials. So what was the problem? And of
course, we won't even mention poor old George Eastman back in the 1880s
trying to figure out why his emulsions varied so much from batch to batch
when he did the same thing every time. Why didn't it work? He eventually
figured it out--one of those pesky variables. And, finally, permit me to
quote from E.J. Wall who wrote one of the definitive treatises on emulsions
(Photographic Emulsions, 1929) and which is still a standard text for the
field (quote taken from the preface, pp. iii and vi):"But the author would
most strongly emphasize the point that if anyone supposes that it is
possible to learn emulsion making by mere reading of a few printed pages,
or to turn out sensitive products with regular characteristics at a cost
that will make a considerable saving, he is considerably mistaken. This
idea is purely chimerical . . . . Successful emulsion making depends upon
so many and in some cases such apparently trivial factors that the
information given must be looked upon rather as signposts pointing the way
than milestones conveying definite and accurate information though no
formula or methid is given that has not been tried out practially." Wall
states that he tested over three-thousand emulsions and used five miles of
paper in four years. And he still stated the above in the preface to his
work. Unfortunately, my personal experiences (although minor in comparison
with Wall's monumental task) confirm his comments. Surely, a new text is
badly needed to correct such obvious errors.
I do believe that a careful worker rigorously testing an emulsion and
working out a formula and procedures can replicate an emulsion. Jim
Browning obviously does, and he does a good job of it. The problem as I see
it lies in assuming that this "perfected" formula will work precisely the
same in the hands of another worker. If I follow your formula and
procedures, they may well work; but they may not meet my needs, and they
may not work well.
I await your rebuttal with much pleasure.
Yours truly,
Rae Adams
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