Why agitate film

This is caused by the developer surging through the development reel. Both these errors can be mitigated by reducing the agitation in both rate times per minute and strength how forcefully you are agitating.

Be gentle! Under Agitation Insufficient agitation of the film often with highly active developers at full strength D, etc also causes streaks and uneven development but it looks very different. This is usually most noticeable: At one edge of the film where development may be considerably less than the other edge of the film Or as streaks that run down below highlight areas or down from the sprocket holes. These look more like the smears. Negatives effected in these ways are ruined but the solution to these problems is simple.

The solution Stick to the following agitation technique with your film. Agitate constantly for the first 30 seconds of development, thoroughly soaking the emulsion. Do not shake the tank but instead gently but firmly invert it and back and forth every 5 seconds.

Take it easy with the tank, shaking the tank will introduce bubbles that will get trapped and cause more problems so be gentle! Give a little twist to the tank as you invert it each way to help move the chemicals around. The rest of the system is adjusted to match the agitation method. Thanks for your responses, guys! 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! I switched from Xtol to HC 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. HC 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 D 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. 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 Hi Andrew, thanks for your comment! I would like to try stand development would be useful for 8mm film!

What's your agitation method? 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? 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.

Mar 28, 1. Messages: I noticed when I developed my first sheet films today that I agitated the trays more or less continuously not much else to in the dark. What is the effect of over-agitation on the film and what is the "correct" agitation for tray developing? Mar 28, 2. Messages: 1, Good Afternoon, Shimoda, Increasing agitation tends to increase negative contrast. If you "more or less continuously" kept the developer moving randomly across the film, using the film manufacturer's recommended time for continuous agitation, you're probably close to proper development.

Mar 28, 3. Messages: 8, If your film was in an open tray and you were gently rocking it, I dont think it will have, much, if any effect. Check the negatives you just completed, if you think they are too contrasty, adjust next time. This is always a trial and error hobby, until you settle on a method that fits your style. Congrats on getting through your first set. I'm happy to see there is no mention of mistakes, so you must be doing it right. Mar 29, 4. The is no such thing as over agitation.

This has been proved many times in tests with agitate and rest compared to continuous in a Jobo processor. You will also find agitation 1 every 15 sec is the same as continuous.

Mar 29, 5. This article is going to go over a number of ways to properly develop your film. As a general rule, the way to agitate your film is to do inversions for the first 30 to 60 seconds. Then, if the development time is less than five minutes, agitate the solution every 30 seconds. Troop and Anchell say if it takes you longer than 5 seconds to fully pour the developer into the tank, then agitate for the first 60 seconds.

If you can pour it all in in less than 5 seconds, then a second first round agitation should be enough. There is a surprisingly specific way to do an inversion.

The idea is that you want to break the normal, laminar flow of water over the negatives. Think of the flow of water like a river. You can see this streaming happen when you pour water out of a pot — the water will condense into streams rather than flow evenly. This effect can cause streaking on the negatives. For the first inversion, rotate the tank clockwise while flipping it. For the second inversion, break the flow of water by rotating it counter-clockwise while flipping it.

When over-agitating your film , use a technique called continuous agitation. This means continue inverting and agitating the film throughout the entire developing time. That means if the standard dev time is 5 minutes, it should be reduced to 4 minutes when continuously agitating the film.

So, that same 5-minute dev cycle will turn into 7. Any changes in density from the beginning will be amplified over time. More on that in this section of the article. There will be some differences, but not enough to have to make you throw a roll in the trash. YouTuber Azriel Knight did a fantastic experiment that clearly shows the differences between over and under-agitating film. In the experiment, he shot the same image across a roll of Tri-X. Then he cut that roll into three pieces and developed them all in separate tanks using HC Dilution B.

The first tank was not agitated at all, the second tank was agitated normally, and the third tank was agitated through the entire developing process.

The resulting images clearly show how under and over agitating the film will change the results. At least with flexible films like Tri-X , there is some wiggle room. I spoke to Knight over email and was able to ask him a couple questions about the experiment, and what he learned from the process.

The Calgary-based photographer said he prefers lower-contrast negatives because of the additional flexibility it gives him down the line. Photo book : Under Vancouver by Greg Girard. At the end of the day, while the experiment was a success, Knight has continued to develop film normally.

Changing the agitation can have some risks.