How Agitation Frequency Affects Black and White Photos

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The work of an analogue photographer does not end when you press the shutter. Back in the dark room, you have creative control over your pictures, and this is where you can use your hands to craft your art.

Agitation is a fascinating step in black and white development. It will directly influence the final result of your negative. From the amount of grain to the level of sharpness and contrast; let's explore the all factors that are effected by the agitation process.

Picture 1 strong agitation of 30 second with 10 second pause. Second picture lower agitation 10 second with 30 second pause. Photos by Elisa Parrino

How To Agitate Your Film

The minimum amount of time necessary for the agitation to complete it's work on the negative is 10 seconds. Since less time isn’t enough to break the flow of the developer solution.

After you pour in your developer apply regular steady inversions for the first 30 seconds. The best way is to imagine drawing an infinity sign ( ) in the air while keeping your hands on your tank. Then, if the development time is between five minutes to six minutes, agitate the solution every 30 seconds for five inversions. If it’s more than five minutes, invert for 10 seconds every minute.

The quicker you are to pour your developer into the tank the better it is, and you can proceed to agitate for 30 seconds. If it takes you longer then five seconds to pour the liquid, agitate for a full minute.

The idea is that you want to break the normal, laminar flow of water over the negatives.

The difference between agitation and inversion is simple. By inverting the direction of the streaming solution onto your negative, we avoid forming lines and sediments. By agitating, we shake up the liquids. When we say "shaking up", we don't mean like an iced coffee, but more like smoothly steering or turning the liquids.

The intensity that you apply during these steps should be steady and controlled. Keep in mind that the time and interval applied between the actions you take is what will influence the outcome. It can increase or decrease the desired results.

Strong agitation of 30 second with 10 second pause. Photos by Elisa Parrino

For this experiment, we wanted to focus on the different results we can have from two different ways of inversions with a roll of Earl Grey B&W 35 mm ISO 100 . We had the same dilution of HC-110 dilution B, same time of development at the recommended time of 6 minutes, and kept a stable temperature at 20℃. The only thing we changed was the inversion frequency.

For the first one we used a 10-second inversion and we paused for 30 seconds. For the second roll, we used 30-second inversions and paused for 10 seconds.

Strong Agitation:

A robust and frequent agitation will reduce the time needed to develop, opposite to the standstill technique. Frequent and energetic inversions will give grainy, contrasty negatives. Issues in overdoing inversion will cause dense negatives and the risk of living sprocket hole signs. Continuous agitation, will lose some of our edges, as the top and bottom of the film will be developed differently to the center.

Lower agitation 10 second with 30 second pause. Photos by Elisa Parrino

Lower Agitation:

Using a very diluted solution, with little to no inversions and agitations, paired with soft movements will reduce grain contrast and increase sharpness resulting in what appears to be a flatter negative. However, you will have a good tonal range to use for printing as there will be a generous amount of details in the shadow. The issue that you could encounter here is bromide stripes over your negatives.

Bromide is a by-product of the reduction of silver bromide to metallic silver by the developer.

If the developer does not have enough time to act evenly on the surface, the traces of the bromide will leave thinner lines (lighter stripes) on the surrounding negative. If this is the technique you wish to use, check out our article on greater dilutions.

Picture 1 strong agitation of 30 second with 10 second pause. Second picture lower agitation 10 second with 30 second pause. Photos by Elisa Parrino

The Results

Overall this was a fun experiment to better understand the effects of agitations and inversions on our negatives. The limitations of a vigorous and frequent inversion are quite visible and difficult to underestimate.

There is a substantial loss in details of the highlights that make it hard to use these negatives in post production either in Lightroom or during printing in a darkroom. We can see that sprocket hole signs are present, damaging the frame; while some loss of sharpness in the images is visible.

With regular agitation, we can achieve a good contrast, and even if the highlights are overexposed, there are still details that we can recover. Having a good tonal range that covers the whole spectrum makes these negatives optimal for printing and post production work. The grain is what it is meant to be for 100 ISO films.

As with anything, you should find your sweet spot that fits your way of shooting, and from where you can develop your own photographic style. We highly encourage you to keep a record and try out different inversion systems until you find what you like.


What is your usual agitation technique? Have you ever experimented in the dark room? Share your thoughts in the comment below.

written by eparrino on 2022-08-23 #tutorials #black-and-white #contrast #grain #experiment #self-developing #agitation-frequency #earl-grey-b-w-100

Lomography Earl Grey 100 (35mm)

Add a touch of class and contrast to your shots with this majestic black and white film.

2 Comments

  1. leisuresuit
    leisuresuit ·

    Awesome tip

  2. eparrino
    eparrino ·

    @leisuresuit I'm glad it can be helpful :)

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