Emulsion Makers Book Club, Selection One: Photographic Emulsions
Following up on a wistful thought by Holmburgers, I'm posting a link to a book I finally finished scanning and posting to The Light Farm last night. Good timing!
The Photographic Emulsion is a compilation of a series of monographs written between the late-1920s and the mid-1930s, by Carroll, Hubbard, and Kretschman. The table of contents speaks for itself. It's a classic and a wealth of information.
If we were to treat this like a brick and mortar bookclub, we'd start at the beginning together and discuss the book as we progressed together. I have no idea if that would work here. No harm in trying. At any rate, happy reading.
Let me be the first to singe up for your "Book Club". It so happens that I have pulled my "ham-string"and am now obliged to sit on my butt for a while. So I will read the book and report back with comments, questions,etc.
Wow, it's great that you've scanned this book! Unfortunately I am not quite into making emulsions, but I love to hear what you emulsifiers are up to.
Here's a question whose answer might lie in this book, but... what sensitizer and/or how would you panchromaticize one of the commercially available liquid emulsions? This kind of discovery could have far reaching consequences for all sorts of alt processors. Any ideas?
I don't understand much (or rather have little idea of the implications of the various schemes presented) but I am going to read anyway. Some things will stick, eventually. I assume the speed mentioned in fig. 1 and 2 (page 18 - 19) is not ASA/ISO?
“Do your work, then step back. The only path to serenity.” - Lao Tzu
Hello to all,
Somewhat high on Oxycodone, I have read chapter 1 . The first thing I noticed is that the initial swelling of the gelatin is carried out in a solution of KBr, rather than in distilled water. I never tried this. But, given the fact that, in 2010, the chemistry of gelatin is still not fully defined, I wonder if there could be a difference between swelling the gelatin in water, then adding KBr and doing it the Author's way.. There could be a difference in the way in which the Br is dispersed along the strands of gelatin. This might lead to a difference in rate of emulsification and in ripening.
But this is pure speculation on my part.
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There does not appear to be any difference between the swelling of gelatin + KBr or the swelling of gelatin then addition of KBr except for the time it takes to do the swelling. KBr slows down the swelling of gelatin!
Some additional thoughts expressed before.
1. The book does not clearly state when active or oxidized gelatins are used for the makes. This makes speed, fog, and contrast variations difficult to evaluate, especially if you move on to the sensitization chapter.
2. The use of colloidal Iodide in the sensitization chapter was in large part misunderstood in that day and age. The Iodide effect was a bit different than what they observed and is used today in most all Kodak emulsions, as the second step rather than at the end of the make due to the latest revised understanding. And, many emulsion makers today say that adding Iodide like this should cause renucleation, but it actually does not if the process is carried out properly.
So, I can say that for beginners, this is a good book but rather dated with information that has changed over the years with better explanations and also I can say that this book starts out by leaving a lot of things out. Burt Carroll was a friend in my early years at Kodak, and just after he had retired. I have had a chance to discuss some of these things with him in the 70s. I think that he would write a totally different book today. I wish I had the resources to write a fully revised edition of his book.
The accepted wisdom today is to dissolve salts in the kettle and add dry gelatin. Then stir while raising temperature. OR....
Add dry gelatin to cold water and stir while raising temperature, then add salt. The latter method is quicker and is currently used. No ions but K, Na and NH4 are used as halide salts when making emulsions. All other positive ions in the kettle as halide salts have bad effects except for a few used at low concentration such as Cd, Cu, Hg, Ir, Os and Rh. These are listed in decreasing useful concentration and they do not work equally well in all emulsions. Cu and Hg are used mainly for toning to get warm toned emulsions.
Actually, you've precisely hit on the value of reading technical historical literature. Starting from the implications, and then circling back to specifics/facts, ideally coupled with some hands-on lab work, is exactly how historical sciences are best understood and recreated.
Originally Posted by Jerevan
Re 'speed': The concept of speed, as we know it as a set of standardized values, is essentially meaningless with 'color blind' (i.e. sensitive to only UV light) emulsions. It wasn't until the 1930s and 40s that the research was done on emulsion sensitivity that was adopted by the American Standards Association. Until then, there were a half dozen different 'standards', but it is almost certain that Carroll and Hubbard were using the system of comparative speeds, based on gaslight papers as '1'.
From the Focal Encyclopedia of Photography, 1958: Material/Relative Speed
Contact papers and contact lantern plates/1
Slow chlorobromide papers/10-20
Fast chlorobromide papers and warm-tone lantern plates/50-100
Bromide papers and bromide lantern plates, positive films/100-500
High-speed pan film or plate/around 100,000.
Poor Bill! Ouch. I can't even imagine reading this stuff on painkillers. On the other hand...maybe that's precisely the way to read this stuff.
Originally Posted by wildbillbugman
Technical historical literature is fine unless it is wrong or misleading due to later advances in science. Unfortunately, Mees begs the issue as do Mees and James. No updates to emulsion technology were made in the literature.
Mees says: One omission in the book requires explanation. A book on the theory of photography should contain a chapter on emulsion making, discussing various methods of procedure and their effect upon the finished product. The author's knowledge of this subject has been acquired in confidence, however, and he is not entitled to publish the material with the frankness which alone would justify publication.
No one has done this, ie. publish a full disclosure on emulsion making. Even Haist has published an emulsion formula with deliberate omissions in it. This is endemic in the entire literature and the readers must be aware of this. I must add to this list of Mees and Haist, the following: Wall and Baker among others including the aforementioned author and referenced in the OP.