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There is a certain joy of really creating images of your own! Having exposed some rolls of film in photographing what you enjoy, there is delayed satisfaction that awaits you when processing your images on film at home. For a modest investment in simple equipment and chemicals, you too can experience absolute joy at the moment your images are finally revealed on film as you open the developing tank.
Indulging in analog photography
Many of us are currently fully committed to digital photography and love our DSLR gear. That includes me! I love being able to test exposure and tweak a shot with the immediate feedback of the image and instant gratification of captured shot data and histogram of exposure! Wow, that would have been a real rush when I was just learning photography in high school.
I learned about photography – film photography, or “analog photography” – when that’s all there was. Polaroid instant photography had an allure, but along with the short-term feedback came some significant trade-offs. A Polaroid image gave us nearly instant feedback (though we had to wait a few minutes for the image to fully develop). Yet that same image was all we got – no negative, no archive, no enlargement opportunities.
Photography, until some 25 years ago, was always about exposing a light sensitive film or plate of some physical dimension. That exposure of some fraction of a second initiated a chemical transformation from latent image to a fully developed image that can be seen with the naked eye.
The wonder of chemical transformation
The photo-sensitive material in photographic film is called a “silver halide.” In particular, the silver halide is silver bromide, or AgBr, its chemical formula. The silver atom readily gives up an outermost electron to a bromine atom forming Ag+ and Br- ions bonded together.
Light hits the film
When a photon of light encounters a silver bromide molecule, an electron in the bromide ion’s outermost (valence band) energy level is ejected and delocalized (able to move) throughout the crystal. When the ejected electron encounters a silver ion (Ag+) the silver is reduced to metallic silver (Ag). This is now part of the latent image. It is literally a photo-oxidation/reduction process where Bromide (Br-) is oxidized by the loss of an electron and then silver ion (Ag+) is reduced to metallic silver.
Development makes the latent image appear
This is just the start of the chemical transformation. The latent image needs to be “developed” by a chemical process to reveal the latent image to be visible. The developer solution is a reducing agent – this means that it drives the chemical reduction reaction to form metallic silver in the developing stage (film loaded into a light-safe tank with developer solution added).
There are many different developers one can use with a variety of films – more on that later. Once a specified time at a given temperature has lapsed for the developer used, the reaction must be stopped. “Stop Bath” is the second chemical solution used to achieve this. Stop bath consists of a solution of acetic acid (the same acid that comprises vinegar) plus an indicator that changes color when the stop bath is exhausted, so unlike the developer which is a one-time use, the stop bath solution is re-used many times until exhausted.
Desensitize the film
The last required step is to render the developed image insensitive to light. Before this “fixation” step the film is still light sensitive and if exposed to any additional light energy the developed image will be fogged or even totally obscured by continued reduction of any remaining silver ions. A typical fixer is sodium thiosulfate (Na2S2O3). The remaining silver cations bond with the thiosulfate anions more strongly than sodium, and thus the silver that has already been reduced is unaffected while the light sensitive silver ion is now irreversibly bound up by thiosulfate.
After the fixing step the thiosulfate solution is saved to be re-used until exhausted (like the stop bath).This post contains affiliate links below. I earn commissions if you shop through the links on this page.
What you need – chemicals
This process is for black and white negative film, such as Tri-X, TMax, HP Plus, Delta, etc. See this blog article for some suggestions if you haven’t shot black and white negative film. Color negative film is just as easy – and I’ll write up a separate blog article next week describing that process and provide specific details.
So here’s the B&W chemicals you will need:
- A wide variety of commercial and home-made developers can be used in B&W photography. A few examples of commercial developers include TMax developer, Rodinal, Kodak D-76, HC-110, Xtol, or Ilford Microphen. DIY developer recipes can be made from instant coffee (Caffenol), green tea extract (Teaol), and even red wine (Wineol). The Caffenol recipe is a good place to start if interested in a DIY developer.
- Stop Bath
- The only criterion for stopping development is to acidify the film, and frankly the use of plain water at a pH of 7 is sufficient for this purpose. Nevertheless stop bath solution is cheap (I still use a concentrate with indicator that is well over 25 years old and it works fine). You can even make a 1:1 dilution with household white vinegar and water for a DIY stop bath if you wish.
- The fixer solution can be purchased as a pouch of crystalline solid thiosulfate that is premeasured for dilution to one quart (or liter) and this can be re-used for many rolls of film before it is exhausted. A separate chemical test solution, called Hypo Check, is sold by many suppliers that when added to a sample of fixer will turn the fixer solution white when exhausted.
- Photo-Flo (optional)
- This optional step is a surfactant solution (like a soapy solution) that is a final treatment of the film surface that cuts surface tension and avoids water spots from forming on the film surface when drying. This is also very inexpensive and the solution is re-used for many rolls of film.
What you need – equipment
- Changing bag
- This allows you to transfer exposed film from the film canister to the developing tank in total darkness.
- Developing tank with (at least) 2 reels
- For beginners a Patterson plastic tank and reels is recommended. It is much easier to learn how to load film on a ratcheting reel than to load film on a stainless steel reel. I have one small stainless steel tank and reel and I have hardly ever used it in the past 25 years.
- Get a decent quality stainless steel thermometer with easy read dial (or go digital for extra $) to process at the target temperature that your film and developer combination calls for.
- You will need a small scissors to cut the ends of film when loading the film into the tank, and again after the film has completely dried to cut into 5 frame strips for storage.
- Bottle opener
- An old-school metal bottle opener is handy to open 35mm film canisters ( in the changing bag!)
- Timer or cell phone app such as Develop! (available in the App Store for iOS) or Dev it – darkroom timer on Google Play for Android phones.
- Use this to accurately time each step of the development process to get consistent results.
- Film clips
- These firmly clip onto the wet film so that you may hang it up to dry – on a clothes hanger, or any other suitable location where the film will not be disturbed for an hour or so.
- Film Sleeves
- Once your negatives are completely dry, archival plastic sleeves are the preferred way of storing and organizing them.
The times and temperature used can vary depending upon the film developer choices made. It will also depend upon whether you need to push process (under exposed film by one or more stops) the film to get proper image density on the film. Many film and development combinations are available at filmdev.org, and here’s an example using Tri-X and Rodinal developer:
- Tap water soak for 1 minute.
- Rodinal 1 part to 50 parts water at 20C/68F for 13 minutes, agitate/slowly invert 5 times every 60 seconds.
- Stop bath for 1 minute.
- Fix with agitation every 60 seconds for a total of 7-1/2 minutes.
- Running water rinse for 10 minutes.
- Photo-Flo rinse 1 minute.
In preparing the developer solution be sure to have about 400 mL for each roll processed in the developing tank. Developing two rolls of film at a time is efficient use of your time, and if your become a prolific film shooter consider investing in a 5-roll tank!
Next week – color processing!
I will cover color film processing in my next blog article. You will find that it is just as easy to develop color as it is B&W film, but the chemicals are different and are a bit more expensive. To my knowledge there are no DIY recipes for color film development, but if anyone out there has ventured in that direction please let me know!
Photo film processing at home is easy and fun! It doesn’t take a huge investment in equipment or chemicals to do this either. I do have one caveat though – if you happen to live in a house with a septic system rather than a municipal sewer, you may not want to dump any chemicals down the drain! Please check with someone knowledgeable about septic system maintenance before putting any chemical solutions down the sink.