film developers and base fog

David Lyga · Jun 27, 2017

I think that it would be both interesting and informative to delineate those film developers which either (largely) negate base fog and those which seem to 'encourage' it (albeit, while enhancing film speed).

In using many film developers over the years I can start this thread by stating that Rodinal, HC-110, and Polydol seem to offer low base density, while XTOL gives a stop more speed, but at the cost of greater base density.

Agree? Other developers? - David Lyga

Petraio Prime · Jun 27, 2017

David Lyga said:
I think that it would be both interesting and informative to delineate those film developers which either (largely) negate base fog and those which seem to 'encourage' it (albeit, while enhancing film speed).

In using many film developers over the years I can start this thread by stating that Rodinal, HC-110, and Polydol seem to offer low base density, while XTOL gives a stop more speed, but at the cost of greater base density.

Agree? Other developers? - David Lyga

Not necessarily. It depends on the ph, type of restrainer, if any, dilution, etc. Kodak claims that 'seasoned' developers produce less fog, but may also cause slight speed loss.

David Lyga · Jun 27, 2017

Seasoned developers have more bromide: that would explain a lessening of base fog. I have found that neither 'excess' alkalinity nor dilution induce fog, as long as the contrast index is the same. 'Type of restrainer' if inherent to the developer, is PART of the formula, thus not an additive 'after the fact'. - David Lyga

Petraio Prime · Jun 27, 2017

David Lyga said:
Seasoned developers have more bromide: that would explain a lessening of base fog. I have found that neither 'excess' alkalinity nor dilution induce fog, as long as the contrast index is the same. 'Type of restrainer' if inherent to the developer, is PART of the formula, thus not an additive 'after the fact'. - David Lyga

Bromide can be part of the formula or not (D-76 contains no restrainer, but others developers do) but re-used developers do accumulate bromide from film passing through it. All film has some base fog, so it cannot be completely eliminated.

trendland · Jun 27, 2017

David Lyga said:
I think that it would be both interesting and informative to delineate those film developers which either (largely) negate base fog and those which seem to 'encourage' it (albeit, while enhancing film speed).

In using many film developers over the years I can start this thread by stating that Rodinal, HC-110, and Polydol seem to offer low base density, while XTOL gives a stop more speed, but at the cost of greater base density.

Agree? Other developers? - David Lyga

Hey David - I am not much afraid of fog.
I often use perceptol in addition I often pull some films.
May be that I am not so often be confronted with fog due to this method ?
I is a real question - I should not be sure
of that my method is the reason for it.
(of having no fog in most cases) ????

with regards

Gerald C Koch · Jun 27, 2017

While such data would be interesting there are just too many variables preventing any values from really being meaningful. Just how the developers are used (temperature, agitation, dilutions, ...) has effects.

Rudeofus · Jun 28, 2017

David Lyga said:
I can start this thread by stating that Rodinal, HC-110, and Polydol seem to offer low base density, while XTOL gives a stop more speed, but at the cost of greater base density.

You solved your puzzle already: speed preserving/enhancing developers are more prone to fog. The smaller a latent image center (i.e. the weaker the exposure), the slower it develops. Fog centers, in this regard, act like tiny latent image centers, i.e. they will develop eventually, albeit very slowly.

If your developer + process conditions are set such that even tiny latent image centers are developed, you will inevitably develop some fog centers, too. Since fog increases granularity and printing times, it is carefully avoided in all those developers, which are not obsessed with speed preservation/increase.

David Lyga · Jun 28, 2017

You are correct, Rudeofus, in that base fog and emerging shadow detail are, to the developer at least, one and the same. Thus, an enhanced film speed is concomitant with somewhat more base fog. But I love 'clean' negatives and posed this question to elucidate and segregate those developers that are 'cleaner than most'. However, even with base fog, the actual print will be good. Actually, one can dip the negative in a dilute Farmer's Reducer and get that negative 'cleaned'.

Petraio Prime: you kind of missed the whole point: I know that restrainer is inherent with some developers, but I wanted to know which developers are MADE that way, instead of having to add something TO a given developer. - David Lyga

Petraio Prime · Jun 28, 2017

David Lyga said:
You are correct, Rudeofus, in that base fog and emerging shadow detail are, to the developer at least, one and the same. Thus, an enhanced film speed is concomitant with somewhat more base fog. But I love 'clean' negatives and posed this question to elucidate and segregate those developers that are 'cleaner than most'. However, even with base fog, the actual print will be good. Actually, one can dip the negative in a dilute Farmer's Reducer and get that negative 'cleaned'.

Petraio Prime: you kind of missed the whole point: I know that restrainer is inherent with some developers, but I wanted to know which developers are MADE that way, instead of having to add something TO a given developer. - David Lyga

I'm not sure what you mean. Low-energy developers (ones that use borax as the accelerator, or none at all) such as D-76 or D-23 generally contain no KBr in the recipe, but after use will contain some ('seasoned'). Almost all developers that use sodium or potassium carbonate, or hydroxide, contain restrainer (usually 0.5g), as do those that use Kodalk as the accelerator (DK-50, DK-60a). The presence or absence of restrainer in the basic formula does not mean anything with regard to fog levels: the formulas are tweaked to provide similar fog densities on the films for which they were intended. More vigorous developers need more restraint. If you re-use developers (most high-volume users do) they will accumulate bromide over time; replenishment is intended to counter-act this. So, I remain confused about what you are asking.

Rudeofus · Jun 28, 2017

A speed enhancing developer is one, which does a better job of distinguishing between fog and image centers, but it practice it can do this only if it allows for some fog development. You could - in theory - mix a developer which still gives you full speed and no fog, but this would happen only right after mixing at one exact temperature and for one type of film. As soon as you allow for process variations, there will be some films which lose speed, whereas others will show some fog anyway. Designers of speed enhancing developers therefore tipped the scale a tad towards fog, and under most processing conditions and with most films these developers will give full or extra speed together with a modest amount of fog. I personally don't mind a bit of fog, since extra exposure under the enlarger is in many cases much easier than with a hand held camera.

Note, that one can not take this to the extreme: as fog builds up further, you start losing differentiation between image and fog. It's a sensitive balance ...

PS: A bleach does just the reverse of your developer, and as the latter, it has difficulties distinguishing between image and fog. As you get rid of fog, shadow detail will start disappearing.

Gerald C Koch · Jun 28, 2017

I have seen a list of developing agents which rate them to their propensity to create fog. However it is on a relative scale using a particular developer and not developers in general. I do remember that paraminophenol produces less fog than its cousin Metol.

Rudeofus · Jun 29, 2017

If a development agent "produces less fog", it could be used longer and film speed could be increased. We can therefore safely assume, that the development agents with the least fog, i.e. those with the best separation between image and fog centers, are these which are commonly used in speed enhancing developers. I have seen several such formulas/products with Phenidone plus secondary dev agent, and at least one (Crawley's FX-11) with Phenidone, Metol and secondary developer. Somehow p-Aminophenol is not popular in this category.

Gerald C Koch · Jun 29, 2017

Rudeofus said:
If a development agent "produces less fog", it could be used longer and film speed could be increased. We can therefore safely assume, that the development agents with the least fog, i.e. those with the best separation between image and fog centers, are these which are commonly used in speed enhancing developers. I have seen several such formulas/products with Phenidone plus secondary dev agent, and at least one (Crawley's FX-11) with Phenidone, Metol and secondary developer. Somehow p-Aminophenol is not popular in this category.

Actually this assertion isn't true. Ferrous sulfate when used as a developing agent produces almost no fog. However it also results in a large loss of film speed. However it was once used extensively especially for wet plates. Extending development time will not increase the film speed to what an organic agent produces. I believe that the same applies to vanadium based developers. Then too with some speed increasing developers there is a trade off between speed and increased fog.

NB23 · Jun 29, 2017

Yes loss of film speed.

Petraio Prime · Jun 29, 2017

Rudeofus said:
If a development agent "produces less fog", it could be used longer and film speed could be increased. We can therefore safely assume, that the development agents with the least fog, i.e. those with the best separation between image and fog centers, are these which are commonly used in speed enhancing developers. I have seen several such formulas/products with Phenidone plus secondary dev agent, and at least one (Crawley's FX-11) with Phenidone, Metol and secondary developer. Somehow p-Aminophenol is not popular in this category.

It's not just the agent, it's also the concentration, accelerator, etc. Try using Adox MQ borax with and without bromide. I bet you won't see any difference in prints!

Adox MQ Borax formula:

Metol 2g
Sodium Sulphite (anhyd) 80g
Hdroquinone 4g
Borax 4g
Potassium Bromide 0.5g
Water to 1 litre

Compare the formula for D-76:

Metol 2.0g
sodium sulfite (anhydrous) 100g
hydroquinone 5.0g
borax (decahydrate) 2.0g
water to 1 liter

Rudeofus · Jun 29, 2017

Of course you can formulate a developer which produces massive fog and still loses speed, and it depends on many factors (some enumerated by Petraio) whether a film developer is foggy or not. And of course you will be able to find film developers which won't produce fog for hours.

But my statements were not about some randomly thrown together compounds, they were always about published formulas created with the intent to make a good developer - a developer which would emphasize one or two properties but provide overall optimal performance within its constraints. Within the realm of established general purpose film developers, one can safely assume that speed increasing developers will tend a bit towards fog, whereas all others will rather avoid fog. There are some advantages from having low/no fog, and you will not give these up unless you can trade these in for other benefits (e.g. speed increase).

And to come back to p-Aminophenol again: It does not matter whether you need pH 11 or pH 5.0 to make some compound an active developer. Both small latent image centers and fog centers will eventually develop, and a good development agent, compared to an inferior one, will have a bigger development speed difference between these two types of center.

Slixtiesix · Jun 29, 2017

Since Perceptol and Microdol X lower the effective film speed, do they also produce lower base fog?

Rudeofus · Jun 29, 2017

These two would be poorly designed IMHO if they were indeed foggy developers. If they show traces of fog with your film, add some restrainer to get rid of the fog.

Petraio Prime · Jun 29, 2017

Slixtiesix said:
Since Perceptol and Microdol X lower the effective film speed, do they also produce lower base fog?

yes, but not much less.

Slixtiesix · Jun 30, 2017

No problem with these developers, I just asked out of curiosity.

MattKing · Jun 30, 2017

David Lyga said:
I think that it would be both interesting and informative to delineate those film developers which either (largely) negate base fog and those which seem to 'encourage' it (albeit, while enhancing film speed).

In using many film developers over the years I can start this thread by stating that Rodinal, HC-110, and Polydol seem to offer low base density, while XTOL gives a stop more speed, but at the cost of greater base density.

Agree? Other developers? - David Lyga

I'm curious why David is concerned about "base density".
With the exception of those who seek to create positives for projection, it seems to me that a moderate amount of base density merely increases printing time a bit. In the case of modern printing papers, this is often an advantage, as times can be too short for convenient printing of smaller prints.
The issue might have been more important with older films, but with modern films being much more able to retain details in highlights, I don't know that the differences being discussed in this thread are that important.
I do understand though the desire to have "beautiful" negatives.

David Lyga · Jun 30, 2017

MattKing said:
I'm curious why David is concerned about "base density".
With the exception of those who seek to create positives for projection, it seems to me that a moderate amount of base density merely increases printing time a bit. In the case of modern printing papers, this is often an advantage, as times can be too short for convenient printing of smaller prints.
The issue might have been more important with older films, but with modern films being much more able to retain details in highlights, I don't know that the differences being discussed in this thread are that important.
I do understand though the desire to have "beautiful" negatives.

Yes, Matt, in a round-about way you answered the question. I really don't like looking at foggy negatives, although I know that they probably will print OK. After all these decades, I know how to read a negative and do not like fog getting in the way of that assessment. - David Lyga

Petraio Prime · Jun 30, 2017

David Lyga said:
Yes, Matt, in a round-about way you answered the question. I really don't like looking at foggy negatives, although I know that they probably will print OK. After all these decades, I know how to read a negative and do not like fog getting in the way of that assessment. - David Lyga

Don't forget that the base itself has some density, to help reduce halation.

http://www.kodak.com/KodakGCG/uploa...wsletters_filmEss_04_How-film-makes-image.pdf

David Lyga · Jun 30, 2017

Petraio Prime said:
Don't forget that the base itself has some density, to help reduce halation.

http://www.kodak.com/KodakGCG/uploa...wsletters_filmEss_04_How-film-makes-image.pdf

Petraio, after more than 50 years in the darkroom, I think that I know that by now. - David Lyga

Petraio Prime · Jun 30, 2017

David Lyga said:
Petraio, after more than 50 years in the darkroom, I think that I know that by now. - David Lyga

Well, it is easy to confuse that with fog.

film developers and base fog

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