More Dyes, Less Silver?

Is it true that today's black & white films contain more dyes than silver? I prefer films that are rich in silver content

(Fomapan and Efke come to mind) for that "look," and the fact that silver lasts so much longer than dyes. I'd like to

hear your

thoughts on this. Thank you.

AFAIK there are no B&W negative films where the image is made up of both dyes and metallic silver. One or the other yes, but not both. What dyes are used are sensitizing dyes to make the film panchromatic. These effect the formation of the image (by extending sensitivity down into red for example), but are not part of the final image. Instead, they are washed out of the film during processing.

Chromogenic (C-41 process) black and white films use dyes, just like color film, which are 'activated' if you will by silver in the emulsion, just like color film. It is processed as color film, and during the process the exposed silver 'activates' the dyes and is then removed in the bleach/fix stage, leaving only dye behind. There are a large number of traditional black and white films which do not use any dyes still available on the market if you don't like the chromogenic films.

 

The lifespan of any given film is estimated, with perhaps Tri-X being the exception, because none of them have been around long enough to tell for sure how long they will actually last. In any event, the lifespan of film depends on the quality of processing and storage - any film that is not stored in the proper conditions will not last as long as film that is. I don't think that any product out there today will degrade in one persons lifespan, baring physical injury.

 

What resources have you referenced to conclude that dye based film does not have as long a life span as silver based film? When you are doing this sort of research it is important to keep in mind that manufacturers stated life expectancies cannot be ruled free of bias. Try to stick to independent testing agencies with long reputations for quality research backed by specialists, and remember that much of what is said on the Internet in general is often fifteenth hand rumor, not fact.

 

- Randy

Mark, there are at least two kinds of dyes used in films, sensitizing dyes whose purpose is to help sensitize silver halide grains to light and dyes that form the final image. Which class of dyes are you referring to?

The issue of whether a film is silver rich has been discussed in many threads. You would have to to quite a bit of scientific testing to prove whether one film had more silver than another. Using a third party or independent reference source to determine how long a negative might last is still a guess. The only certain way is to wait many years and then examine the material.

Sensitizing dyes are essential to formation of a silver image unless you only want blue-sensitive slow film. These dyes do not become part of the final image. Silver-rich is a sales pitch. Most of the silver goes out in the fixer. The effectiveness of a particular emulsion depends more on the shape of the silver halide crystals than on its "richness".

 

Some developers, including pyrogallol, catechol and even hydroquinone can produce a silver image that is dyed in proportion to the amount of silver in the image. Thus if you bleach the silver out of such a negative, you will still see a dye image and can in fact print that dye image on very high contrast paper. This kind of development is applicable to any silver halide film and it is your choice whether to use it or not. It has advantages for some who print on several different media, as it produces a negative that has low or normal contrast for VC paper and high contrast for fixed grade and platinum or palladium.