Richard Knoppow (dickburk@ix.netcom.com)
Wed, 03 Mar 1999 11:51:22 -0800
At 10:23 PM 3/2/99 -0500, you wrote:
>
>On Wed, 3 Mar 1999, Charles Steinmetz wrote:
>> Following some unwarranted sniping at Rae, let me confirm that there are a
>> zillion variables that WILL foil anyone's chances of simply following an
>> emulsion recipe and getting the same result as the author. To name four
>> very quickly:
>
>I'm glad you mention that Charles. I myself was quite disturbed by the
>instant contempt-hostility on Maxie's part. He turned what could/should
>have been a fascinating discussion into instant confrontation. It's not so
>much the facts (if no one can be wrong on this list, the bandwidth problem
>is solved) it's the manner -- he was RUDE ! I thought we were going to
>be CIVIL from now on ??? Or was that some other list?
>
>> (1) Gelatin. All gelatins are different, and will react differently both
>> physically and chemically with the forming halide crystals.
>>
>
>I'm also glad you mention gelatin (and spell it right!). I found my source
>(and lost it again, natch) about what the cows have eaten -- a mustard
>plant -- having a big effect on the gelatin. But I think it was Sil who
>told me that's a thing of the past, now they *rationalize* or regularize,
>or whatever, the gelatin with.... what was it? Gloy?
>
>I'll also mention that MY gelatin hasn't been doing so well. Are you
>there, Sandy? So I had a a litre of 3% gelatin (Knox) left over, and put
>your thymol mix in it (sure stank up a storm -- sort of like an old ash
>tray). And left it standing with just a magazine over the top. After about
>a week it had a layer of water on it. Now two weeks after that, it's got
>about an inch and a half of water across the surface and the gelatin
>itself looks ... turgid. Doubt I'll dare use it.... But it still smells
>like ash tray.... doesn't have that fetid odor bad gelatin gets.
>
>What do you suppose I did wrong? This was sitting, BTW, near the
>humidifier. Could that have affected it (even tho loosely covered)?
>(Talk about variables !)
>
>> Charles (preparing for the time when silver-gelatin is alt)
>>
>
>Charles, have you tried gum printing? You'll never look back...
>
>If worst comes to worst you can just go out in the yard and dig your own
>pigment. And gelatin is used in so many commercial processes we'll always
>get some kind or other...
>
>Judy
>
>
The story about George Eastman's experience with Gelatin is one which
appears in many places. I think Meese repeats it in his book _From Dry
Plates to Ektachrome_ and elsewhere.
The story must date from before the turn of the century. From what I read
in the technical literature commercial emulsion makers purify the Gelatin
they use to eliminate _all_ trace materials and then add what they want.
Its obvious that Kodak and others can make _very_ consistant emulsions with
control over what must be a tremendous number of variables. The fact that
highly consistant color film is being made is the proof of that.
Traditionally, emulsion making has been the heart of the photographic
materials industry. Because of that it has been surrounded by great
secrecy; most of the technology is considered to be propritary. Mees says
in the introduction of _Theory of the Photographic Process_ that he is
unable to write much about emulsion making due to his obligations to Kodak.
He was supposed to have been one of only about four people who actually
knew what the processes were in detail. George Eastman, during his
lifetime, being one of the others.
In another book on the Kodak labs (I don't have the title handy and the
book is boxed away somewhere) it is pointed out that those in the Kodak
labs charged with improving Kodak products had terrible trouble finding out
what actual emulsion making practice was. The superintendant of the
emulsion making division simply would not give information to anyone. It is
stated that many researchers left the labs because of the frustration.
While patents are useful in protecting technology which is changing
rapidly it is less useful protecting fairly stable technology where keeping
trade-secrets is more effective. This seems to be the case with most
traditional photographic sensitive material technology.
When Agfa discovered the use of gold sensitizing it caught Kodak with
their pants down. It took Kodak several years to catch up with Agfa, who
was able to essentially double the speed of all thier films without
compromising grain, etc. Eventually Kodak managed to find a way to get an
equivalent effect. I don't know just how.
During WW-2 the US government seized all property of German companies.
That included Agfa-Ansco. Agfa made film and paper in the US so all the
machinery, formulae, and techniques fell into government hands and probably
also found their way to competitors.
Enough.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
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