Film acceleration

A multi-step processes designed to push color film to create Pointillist effects with intense grain as well as many unpredictable and extraordinary outcomes.

Writer and photography / Claudia Wornum

Essentially, it can appear as very intense cross processing with local solarized elements.
Initially, I learned of this method in the 90’s from seeing the amazing work of committed ‘accelerators’ in a communal lab.
They generously shared with me the how-to article from the now defunct magazine Darkroom Photography. 
The issue was from May 1989 written by Rand Molinar, titled “Film Acceleration”. If you goggle these words, there are a number of sites that will explain and guide you as well. Also, Robert Hirsch describes it in the second edition of Color Photography.
These various recipes can be quite detailed and rigid. My method is quite fast and loose as I enjoy being surprised at the end. Basically, you’re reversing slide film into a color print negative with a bleaching step in the middle.
Necessary is the C-41 process, this being how color print film is developed. The chemistry can be found online and it’s a relatively simple procedure and better still, the same for all color films! There are also YouTube tutorials. HOWEVER, 
It is quite toxic and must be handled carefully with a respirator and gloves!
It is crucial to dispose of it, as many photo chemicals require, as toxic waste with your municipality.
If you’re not interested in this D.Y.I. extra step, there may be labs that will process it for you although this could be quite a challenge. At the point the film is ready for this step it has been bleached, looks weird and scary to those unfamiliar with unconventional processes, such as a commercial lab.
I have been reassured by those brave enough to cooperate that it can be handled as a simple cross process (slide to negative).
Here is my first accelerated image, in which I followed the directions loyally:

Claudia Wornum Film acceleration

Below are the later variations in which I used other black and white film developers instead of Acufine. I have found that this process is forgiving, predictable and less ‘alternative’ if the procedure is followed to the letter, yet when I began to get eccentric deviations, I often wasn’t able to exactly reproduce those results.
I believe this is due to the following variables: the film I use is always quite expired (as in decades) and the conditions I shoot and store it in are not consistent, temperature-wise,
I often use metal pinhole cameras, subject to temperature shifts and light leaks.
I also do not keep detailed track of exact development temperatures and times.
Consequently, I encourage you to try the straight method 1st,  then tweak it and, unlike me, keep track of the details.

Claudia Wornum Film acceleration

I have more of my imagery on my Alternative Photography gallery page.

The overall procedure:

  • Shoot color slide film at a higher film speed than its ASA
 (at least 2-3 stops faster).
  • Develop it in black and white negative film chemistry.
  • Bleach it in color bleach or a homemade version that I have included.
  • Then wash and develop it as a color negative.
  • Print on color C-print paper and process with RA-4 chemistry or scan it digitally.

Claudia Wornum Film accelerationThe specific steps:

  • You begin with color slide film; the higher film speeds will produce more grain and dramatic effects. Also, the higher  the ASA, the longer the development, as shown in the chart below. Please bracket your exposures ½ f/stop to 1 full f/stop stop both directions.
  • The range of black and white developers is at your disposal, I have found this exploration a world of fun and encourage   you to do so. Having said that, for the initial 1st batch, uses Acufine, it’s more stable, it’s what the original article recommends and you’ll have an effective base line for future departures.
  • Experiment with varied lighting situations: indirect vs. full sun and harsh shadows, natural light vs. strobes, etc.
  • Also recommended is a 2-minute pre-soak in water at 75 after exposure. Agitation will release air bubbles that may adhere to the film surface upon immersion.
  • Agitate normally, in development, as you would in developing black-and-white film (per your normal procedure).


Film Speed Suggested Exposures Settings Developer Time Temperature
100 400 12 minutes 75
200 400 9 minutes 75
200 800 12 minutes 75
200 1600 16 minutes 75
200 10,000 25 minutes 75
160` 320 9 minutes 75
400 800 9 minutes 75
400 1600 12 minutes 75
400 3200 16 minutes 75
  • After development, rinse the film in water for 30 seconds
  • Fix with a NON HARDENING film fix for 5 minutes and wash the film as you would in any black and white film process, for 10-15 minutes.
  • At this point you can complete the remaining steps in room light. It is wonderful to be able to pull the film out of the canister and check on it’s progress. This is another reason I encourage you to do the C-41 process yourself.
  • Bleach the film for 10 minutes in a C-41 color bleach or an E-6 positive film color bleach or make your own (use with care: it’s highly toxic and as with the C-41 chemistry, dispose of it with your community’s toxic waste system, NEVER PUT IT DOWN YOUR DRAIN!)

Start with 750 ml of water at 75 With constant stirring, 
add the following:

  • Potassium Ferricyanide: 30 grams
  • Potassium Bromide 10 grams
  • Water to make 1 liter


  • Wash the film for 10 minutes but do not use Photoflo or any other solution
  • You are now ready for the C-41 process. The film will look bleached and pink-ish and as I said, not appealing to traditional labs.
  • The C-41 chemistry is available online in nifty kits with instructions.
  • The process consists of development for 3 ½ minutes at 100
  • Bleach for 6 ½ minutes at 75-100
  • Wash for 3 ½ minutes
  • Fix for 6 ½ minutes
  • Final wash for 3 ½ minutes
  • Dry and you’re done!

If you’re doing this all at home, it takes about 1-½ hours for the entire process.

Claudia Wornum from San Francisco takes pinhole photographs of landscapes. She also works with lumen prints, solarization and film acceleration. See Claudia Wornum’s gallery here.

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