PDA

View Full Version : PE.. Food dyes



Pages : 1 [2]

avandesande
12-08-2006, 11:18 AM
After looking into it a little more, it appears that the vinyl linked heterocyclic compounds stick to the surface of the silver grains which is why so little is needed. Other dyes may work but not very efficiently.

avandesande
12-08-2006, 11:27 AM
Are you referring to "The theory of the photographic process"? In your opinion would it be possible to put together a 'good enough' dye package using the published tables?


Struan;



This two volume set has never been published for obvious reasons, but part of it is in Mees and James and part is in Haist. These are the 'unclassified' parts.



PE

Photo Engineer
12-08-2006, 11:28 AM
It is nitrogen in the heterocyclic ring that attaches to the surface AFAIK. And, they can stack up in groups called "J" aggregates based on the work of Dr. Jelley at Kodak. This shifts sensitivity to longer wavelengths.

So, a green sensitizer can form a "J" aggregate and become a red sensitizer. These types of dyes are well known for strong adhesion to the surface of an emulsion. I believe that the red sensitizer in Kodachrome is actually a green sensizer that has formed a "J" aggregate. At least, that is what I seem to remember.

PE

Photo Engineer
12-08-2006, 11:31 AM
Are you referring to "The theory of the photographic process"? In your opinion would it be possible to put together a 'good enough' dye package using the published tables?

Yes, by Mees and James. This was the final edition of that book.

IDK, I never studied their tables well enough. Kodak used to sell about 15 dyes from that list at quite reasonable prices, but no longer sells them. I fortunately have a complete set now and can make a pan film. It took me nearly 3 years to get there though.

I don't intend to make a pan film as it is too difficult to do at home.

PE

Struan Gray
12-08-2006, 02:03 PM
The Gurney and Mott work is a classic well known at Kodak. When we are first hired at Kodak in research we take a very long course in photographic science and engineering, going to regular classes with homework along with our normal job.

We have a huge set of notebooks that teach every phase of this, and the work is accompanied by a lab where we first do hand coatings and then machine coatings. We do color and B&W both.


Lets hope the notebooks eventually make it into the public domain as Kodak adapts to a digital world. (Or doesn't). I know that some of my collaborators' collaborators on the solar cell basics got money from Fuji on a regular basis, so fundamental research still goes on. Some of the modern forms of X-ray spectroscopy and my own field, tunnelling microscopy, have allowed a more detailed understanding of both how the molecule attaches to a crystal, and how the charge transfer occurs.

Neville Mott was the grand old man of the lab when I was doing my PhD. I met him several times, but never talked about anything substantial. The only photographic connection I had was listening to the lab photographer gently complain that he was being repeatedly asked to make copy prints of a Vatican photo of Mott meeting the pope.