Effects of agitation on grain, contrast, time etc.

Discussion in 'Black and White' started by ciaran_mcmenemy, Oct 21, 2015.

  1. Normal agitation for black and white using a patersontank (or what I've heard, anyway) is to agitate the tank for the first thirty sec, then one cycle for every 30 sec that passes. The agitation takes the form of rotating the tank while turning it over and back (inversion), and tapping it to dislodge any air that might have settled.
    What if you chose to agitate it differently? Here are some scenarios:
    1) continuous inversions for the whole of the developing times (for this and the rest, assume it is still being tapped to sort out air)
    2) continuous agitation for 30 sec every minute
    3) faster inversions for the usual process
    4) vigorous agitation (shaking it, really rushing it. I know about the sprocket hole issue, at least)
    if any of you have tried these or know what to expect then please say! I'm thinking that increasing agitation will increase the grain, contrast (more 'punchy') and decrease the development time. but I need some guidelines.
    -thanks-
     
    lieven_van_meulder|1 likes this.
  2. Ciaran, I cannot give a complete reply (not enough experience) but do consider that not all developers react alike. With Rodinal I use half the agitation as usually recommended, as grain becomes a lot more apparent with more agitation in this developer, and I didn't like it. ID11, I follow the normal agitation scheme, and it's fine. I've noticed some films getting very contrasty, while others react more 'relaxed' (still more contrast, but not too extreme) - but the development times could also have played their role there.
    In short, I do not think there is a single answer, and you should always consider the effects of your agitation for a given combination of developer/film (and exposure)/temperature. In the end, agitation is about managing the reaction ongoing between developer and the emulsion, and the reactions aren't all alike. Meaning: in order to really understand all the effects that the agitation 'scheme' will have, you need to keep all other variables identical.
    Maybe it's easier if you explain what you'd like to achieve and what you're using.
     
  3. The general rule is that the overall "amount" of development is affected by a combination of time, temperature, and agitation. With more
    development, we usually expect higher contrast, as well as more grain. But if you make adjustments to keep contrast the same, then the
    amount of grain will probably also stay roughly the same.

    If you want to take a system based on intermittent agitation, and change to continuous agitation, then you should probably shorten the development time somewhat.
     
  4. As a general rule, increased agitation intensifies density in the highlight areas, which leads to more difficult printing (to not blow out highlights in the print). I've had better luck with less aggressive agitation routines, leading to much easier-to-print negatives, holding detail in the brighter areas of the scene. With chemical in motion less (longer intervals), chemical activity depletes more quickly where it is being consumed most in the process...converting the highlight areas. I'm over simplifying for brevity but this also allows the less dense shadow areas of the negative to process more completely with less chance of blowing highlights in order to fully pull the information from the negative's less exposed areas. As mentioned, this behavior varies by film and developer, too.
     
  5. Under-agitation can cause bromide drag.
    Certainly agitation patterns can affect the HD curve and acuity. But they are a way of achieving that which can have "repeatability" problems. You really want repeatable results when developing film.
    I'd recommend you get a copy of The Film Developing Cookbook.
     
  6. Developer exhausts out faster in the highlights and slower in the shadows. Agitation puts fresh developer to the surface of the film. Increased agitation increases contrast which is compensated for by reducing developing time up to 10%.
    Rotation at the end of an inversion cycle smooths grain appearance but rotation in one direction only causes streaking. Rotate opposite direction every other inversion cycle for best results.
    I use inversion agitation for 35mm 2 reel tank, 30 seconds to 1 minute at the start then 5 to 10 inversions every 30 seconds thereafter. I notice no difference between 5 and 10 inversions every 30 seconds and little difference between inversion cycles every minute and every 30 seconds. I process 4x5 sheet film on a manual rotary base with consistent agitation. I notice no to minimal difference of the sheet film and 35mm or 120 developed in a tank with 30 second inversion cycles. If I had a densitometer, exposed different formats to the same scene and lighting and processed each my normal way there might be a slight difference in the tonal values.
    As stated in a previous post the results you get will depend on the developer you use. The type of developer will have more effect on grain than agitation. Experiment and find the method that works for you or what effects different techniques have on the finished negative. Tank and reel design will affect the outcome also due to the differences in fluid flow within the tank. One technique may work better with one lighting type such as bright, high contrast versus low contrast or dim lighting.
     
  7. [​IMG]
    the above is the sort of effect that I was hoping to achieve through agitation. it's not the best example, but it demonstrates mainly black or white with little grey. I'm sure it could be done with a scanner, but I'd like to have it done as the first generation image.
    thanks for your replies. I had a look at 'bromide drag', it basically leaves streaks? I use Ilfosol-3. no major reason, it's just that it was available when I started out, and I can stick with it. what about you all, what do you use / get from your chemicals?
    I really appreciate the technical answers. Looking at, for example, HP5 400 with I-3 at 1:14, the time is 11min. With constant agitation the time is reduced by 10% to almost 10 min, will this give the look I want to achieve?
    anyone bother to use the agitator stick?
     
  8. I use HC110 currently and like Xtol. I am not familiar with Ilford developers. It is going to take more than agitation to achieve the effect you want. Part of what you are seeing is from the printing, newspaper or magazine.
    I would start with normal exposure and over develop 10% to 15% then try 1/2 stop under exposure with a 10% to 15% over development. A 5% change in development can be seen in the negative, a 1/3 stop change in exposure can be seen in the negative and printed at paper black in wet process. Have fun experimenting, keep careful notes, and change only one variable at a time so that you know what effect it is having on the final negative.
    Scanning and post processing software may be the route to go.
     
  9. Kodak gives times for large and small tanks, with every 30 seconds for small, and every minute for large.
    The fluid diffusion is different for larger tanks, so the agitation is different.
    Compensating developers try not to overdevelop the highlights by not agitating too much, such that the developer in those regions has less activity. Two bath developers like Diafine do this, as does stand development. But stand development agitates in the beginning when most of the action occurs, then slowly allows the shadows to develop without agitation.
    There are systems that use continuous agitation. The Unicolor film drum from some years ago, and also the continuous moving film process used by large labs and mini-lab machines. The rest of the system is adjusted to match the agitation method.
     
  10. Thanks for your responses, guys! what would you say the main differences between HC100 and Xtol are?
    I had a suspicion that it was due to printing, but since over-agitation is supposed to have a contrast effect, I was wondering... Thanks for your explanation of compensating devs, I wondered why the times were different for them.
    Nice photos, Wouter!
     
  11. I switched from Xtol to HC110 as I was not processing enough film to reach the capacity of Xtol before it died, about 6 months after mixing.
    Xtol gives similar local contrast to D76 but finer grain.
    HC110 is a concentrate that you mix just before use and lasts forever in concentrate. Image results are very similar to Xtol.
    ID11 is Ilford equivalent of D76.
    Ilfotec HC is Ilford equivalent of HC110.
     
  12. Slightly off topic, but I picked up tips about 'Stand Development' here and have done a few films with this system to date. I wouldn't go back to any other way now, as the advert might say.
    3 different films --Kentmere, Fomapan and Delta 100 in Rodinal, dilution 100 to 1 for an hour (the Delta was done for 1 3/4 hours in 200 to 1 just to see what happens) Agitation for a few seconds at the start and a few more halfway through, but nothing severe, just gentle. I am amazed, as it seems to go against all the things we've been taught. No grain and nicely developed. I recommend every one try a film they aren't too bothered about with this method, or even an off-cut with a few images on.....you are hardly spending any money on developer, so there's no waste to speak of !
     
  13. Hi Andrew, thanks for your comment! I would like to try stand development (would be useful for 8mm film!) but, no dark room yet.
    What's your agitation method? just pull the tray back and forth? I can imagine it would get messy if you're not careful.
    With the long, long development, what do you do to maintain 20'C?
     
  14. Hi Ciaran,
    I don't have a darkroom either at present, but I use a changing bag- the largest I could find because I find my hands sweat and make the film more awkward to load with a smaller bag.I use Paterson tanks and don't worry about the 20 deg side of things! I do at the start have the developer at 20 deg, but just let it sort itself out after that. I daresay this is not a system to use outside in the winter, but indoors things are happening so slowly that it hasn't seemed to matter so far...crosses fingers and taps head.
    I recommend looking at the topic posted by Michael Ferron on April 16th this year (2015) called "Sometimes You Find That Holy Grail". I don't know how else to direct you there, as I found it by looking at my own posts. But of course one thing leads to another and there is so much info out there. I hope you can find it OK as it is very interesting to learn a bit more about this method.
     

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