Agitated About Agitation

Hi All,

I have a question on agitation and it's effects on grain. Some individuals indicate that agitation does have a significant effect on grain visibility while others believe that is not the case. I'm of the understanding that agitation can have a major impact on grain.

So, my question is... does the amount and method agitation have a significant effect on grain visibility?

Snapshot,

I have often wondered this myself and so I'll venture a statement based what I've read. I have not found in any text that I have that the manner of agititation itself specifically affects grain visibility. I know that choice of developer affects resolution and accutance seen in the final print. In "The Negative", quote: "the dark grain specks visible in the print are actually the spaces between the grains of the negative; since negative grains withhold light during printing, they appear white in the print." Additionally, "grain itself is a property of the film, and therefore largely predetermined once the film has been selected."

Chuck

Hi Chuck,

Thanks for the excerpt from "The Negative". I know that when I change my agitation, tonality is affected. However, I couldn't see or demonstrate reliably a correlation between agitation and grain, even though I thought there was one.

I too haven't been able to distinguish a difference in grain between agitation methods. With that said, to me it makes sense that when you agitate fairly actively you will develop the highlights, subsequently causing more contrast. With more contrast I would expect grain to be slightly more visible.
But I don't look for grain when I print either. I don't care. If it's there I welcome it, if it's not there well it's not there. Nothing I can do about it. It's the content that matters anyway to make it interesting in the first place.
- Thomas

Until recently I fond nothing to indicate that agitation had any significant effect on grain size. However, a few months ago I started to use Tx and Rodinal 1 + 50 with reduced agitation (two inversions every third minute), similar to a technique I use with Pyrocat 1+1+100. When comparing the negatives produced using this technique with negatives developed in Rodinal 1 + 50 (with agitation every thirty seconds) there is a considerable difference in grain size.

I have used the same EI and negative density and printing times are similar, but the grain is larger on negatives processed with reduced agitation. I find this quite perplexing since I have previously developed Tri-X in Rodinal 1 + 100 semi-stand - which, in my environment, produce similar grain to Tx developed in Rodinal 1 + 50 with normal agitation.

maybe this is leading in a direction not intended by "Snapshot", the starter of this.
Since I'm new to apug I am not entirely sure if it is considered "okay" to ask different things in another thread, just tell me.

I wonder alot about agitation too, but haven't noticed huge differences. Most of the time I agitate for the first 20 seconds and then something like 8secs out of 30.
How does agitation give different results? What does it really do? I'am thinking especially about the relation between the time and agitation. If I have a standard technique for a film, but shot a roll of the film in more dull light, is it a good idea to agitate more and cut down the time, to get more contrast for the same density? less agitation and slightly longer, if shot in "harsh" light? Or isn't it not really necessary to adjust times.

Is there a lot difference in 2 agitations in 30seconds and 4 in a minute? How exactly will this be visible?

Is it a good idea to agitate pushed film less, to preserve a good tonality, because the extended time will give you hard contrasts anyways.

Talking about small tank development and 35mm.

Maybe you want to recommend a book.

Well, it seems there is anecdotal evidence to support that agitation does impact grain. I'm wondering if it is possible to explain from a chemistry standpoint why (or why not) grain is affected?

I don't know whether agitation affects grain, but I do believe it affects acutance. Vigorous agitation is said to "round off" the corners of the grain, reducing the apparent sharpness of the image. I witnessed this myself. I used to develop film in a Jobo on the recommended high setting. By simply slowing the Jobo to the slow setting acutance improved. Going back to manual agitation improved it more. Changing to a high-acutance developer and minimal agitation made a startling difference, especially when compared head to head with the Jobo/high speed combination.

I'll explain to Fabian what happens with agitation and time. Generally speaking (I am not a moderator here, this is just my opinion) it's better to search old threads. The search mechanism is OK and has gotten better all the time. If you can't find it in the old threads, start a new one.

The factors that affect your development time are:
1. Film
2. How much exposure did you give your film
3. Developer
4. Developer concentration
5. Developer temperature
6. Brightness range (if your scenes are very contrasty, you still need to get a lot of exposure to get your shadows so highlights will receive a LOT of energy, which in turn means you'll need to hold back development time)
7. Agitation pattern.
In regards to agitation, what happens is that if you slow it down to say a couple of inversions every three minutes, the developer exhausts 'locally' in your highlights and you get a compensating effect, holding back the highlights. Since the highlights received more light energy at the time of exposure, it takes more developer 'activity' to develop them. I'm confident that the effect varies from one developer to another.
I have been almost exclusively using Rodinal and Pyrocat for the last years, and they are both compensating high acutance developers. Like Dan (FirePhoto) says, acutance changes with development time too. I've witnessed a print with the enlarger head all the way to the 8 foot ceiling and paper on the floor, with a 50mm lens from a 35mm negative being pin sharp. The neg was from Agfa APX25, developed in Rodinal 1+300 for three hours. That's when I started wondering about this phenomenon too.

I hope that explains it.

- Thomas

Doesn't agitation affect development time and therefore more agitation will reduce required development time or increase total development; therefore contrast and grain. I develop in a jobo (always at slow speed) and always with a pre wash. I have never had trouble getting grain or no grain just by reducing or extending development. I too have never used the high speed setting on my Jobo. I think the recommendation was to do with stopping natural straight line water flow across the negative. I just felt that with 8 films in a drum, it would wreck the machine in too short an order so use the slow speed whatever the tank I'm using.

Richard Harris said:

Doesn't agitation affect development time and therefore more agitation will reduce required development time or increase total development; therefore contrast and grain.

Click to expand...

Richard, my thoughts on your statement and I hope to tie it to the OP.

Development time is, typically, determined by temperature of the solution; it's much easier to standardize that way. I would rather keep my agitation patterns constant with "normal development", "expanded development", or "contracted development". Certain compensating development procedures will require altering the agitation frequency to achieve the compensating effect, but when not needing a compensating effect (i.e., when your SBR's exposed on the film are not so great so that they can be handled with contracted development), I suggest keeping the agitation pattern the same as well as the temperature.

The frequency of agitation strongly effects density in the exposed areas of the film. It determines how often during the development time you allow unexhausted developer to act on the emulsion. The longer you allow this to occur throughout the development time the more and more silver will be deposited in the more highly exposed areas of the negative. Thereby increasing the contrast from the lesser exposed areas of the negative.

Increasing the development time will increase the visible grain in a major way primarily, as I understand it, because the longer time is allowing more clumping of the silver grains of the emulsion. Larger clumps, more spaces between the clumps (esp with greater enlargement), and hence the appearance of more visible grain.

The OP's question has triggered in me a bit of study in every book I have and I still cannot find anything that indicates that agitation has a large impact on visible grain and I can't find where it is mentioned at all. Does it have some impact, I think the answer is probably yes, but IMHO merely because it is part of the development process. But it has its major impact on negative density, therefore, maintaining consistent patterns of agitation is crucial. The properties of the film itself combined with the choice of developer and development time have the "major" impact on visible grain.

I have now developed a small headache . Hopefully I have not made a glaring mistake in the above comments, but I'm sure, as it should, it will be pointed out if so.

Chuck

Snapshot said:

I'm wondering if it is possible to explain from a chemistry
standpoint why (or why not) grain is affected?

Click to expand...

I've a theory which I think will hold. It goes somewhat
along the lines of the bromide effect and has to do with
localized ph. The by-products of development are acidic
and thus lower the developer's ph. So with less frequent
agitation the developer is in effect a lower ph developer.

The film itself and the ph of the developer are most
decisive in grain formation; the slower the film, the
lower the ph, the smaller the grain.

The effect will be most noticeable with developers of
little ph buffering action as considerable local ph drop
is more likely.

Another factor may be a lack of in-situ regeneration
even though Crawley associates that with extremely
low sulfite levels. Dan

dancqu said:

I've a theory which I think will hold. It goes somewhat
along the lines of the bromide effect and has to do with
localized ph. The by-products of development are acidic
and thus lower the developer's ph. So with less frequent
agitation the developer is in effect a lower ph developer.

The film itself and the ph of the developer are most
decisive in grain formation; the slower the film, the
lower the ph, the smaller the grain.

The effect will be most noticeable with developers of
little ph buffering action as considerable local ph drop
is more likely.

Another factor may be a lack of in-situ regeneration
even though Crawley associates that with extremely
low sulfite levels. Dan

Click to expand...

Well, this certainly is a good enough theory in my book.

Every movement in the physical world has an associated time constant. I'm not referring to relativity, but to Newtonian physics. To move from one place to another takes time. To change a chemical compound in solution from one form to another takes time. The amount of time it takes depends on concentration, viscosity, electromagnetic forces, etc. What puzzles me about most explanations of the effects of agitation is that more dilution and less agitation are said to cause the edge effects we love sometimes and hate others by transient changes in pH and/or concentration of the developing agent(s). Carried to the extreme, we should dilute to infinity and wait to infinity for something to happen. I jest, of course.

A theory must not only explain what is known but must predict what has not yet happened. It was said about Freud and his psychology "He explains everything, but predicts nothing." My first experiments with stand developing seemed to show that it was not a good thing to do because development changes not only pH, but also local densities of developer causing flow patterns of "bromide drag". I don't remember if these flows were up or down. If they were upward flows, it would explain how it is possible to avoid bromide drag by diluting to the point where the exhaustion products are of the same density as the diluted developer. I found streaks even when developing film face down, so that is a possibility.

PH is of course a factor. A developer using borax as buffer, like D-76, might be expected to have pretty constant pH. However, the time constant of buffering enters in. A higher concentration of borax will not have significantly higher average pH, but local pH changes will be buffered out more rapidly. If you add more borax to D-76, you will see a more rapid development in spite of the fact that pH before and after will be the same. I can remember old timers using up to 20 grams /l to boost film speed. Essentially, they were using D-76 replenisher as developer.

I'm wandering again.

Snapshot said:

Hi All,

I have a question on agitation and it's effects on grain. Some individuals indicate that agitation does have a significant effect on grain visibility while others believe that is not the case. I'm of the understanding that agitation can have a major impact on grain.

So, my question is... does the amount and method agitation have a significant effect on grain visibility?

Click to expand...

Agitation does not have a direct effect on graininess. The effect is indirect which is probably where the confusion lies.

What does have a direct effect on graininess is density. Consider developing two sheets of film, same scene, same exposure. If all other things are equal (same film, developer, dilution, agitation technique, temperature, etc.) and all you do is increase development time for one sheet over the other sheet, the sheet with the extra development time will have a higher Dmax. It will also have more graininess.

More vigorous agitation has a similar effect. If everything else is equal and you increase agitation for one sheet over the other sheet you get a similar increase in Dmax and therefore a similar increase in graininess. But this increase in graininess is due only to the increase in density; it is not due to the agitation itself.

By what has been stated in this thread, any grain intensification observed during film processing is largely due to density increases. Therefore, two identical rolls of film that are developed with equivalent development times, the roll developed with more agitation will appear to have more grain. This is because density increased to a greater degree due to the increased agitation. This would explain some of the past observations that I've experienced.

Thanks everyone for your input.

gainer said:

A theory must not only explain what is known but must predict what has not yet happened. It was said about Freud and his psychology "He explains everything, but predicts nothing."

Click to expand...

True enough. Good theories go on to explain observations seen and can make forecasts based on their model. I guess I was looking for the 'theory of granularity.'