The Effects of Time and Developer Concentration on Black and White Film
While photography can be a precise science, involving the exact combination of chemicals, temperatures, light, speed, and time, it is also a highly forgivable medium. By altering what would normally be thought of as a fixed aspect of the photographic process, the photographer is able to compensate for weaknesses such as over or under-exposure of film and over or under-development of film to produce a good print with a clear black, a clear white, and a spectrum of grey tones. Using this knowledge about the flexibility of photography, I will purposely be creating “bad” negatives by drastically changing the time the film stays in the developer bath. This is the effect I will be creating in my first experiment Then in experiment two, the times from experiment one become constants, and my variable is now the concentration of the developer. I am going to attempt to create various concentrations of developer to counteract / correct the visual results the bad negatives would normally display when printed on paper.
(Image from The Darkroom Handbook)
Photographic images have been around for more than 150 years. While the methods by which they were produced have changed significantly, the general chemistry has not. The formation of black and white negatives and images relies on the reactivity of silver halides, such as silver bromide, silver iodide, and silver chloride, to light. To manufacture black and white film, silver halides suspended in gelatin create an emulsion that is spread onto transparent plastic and allowed to dry. This is known as dry plate photography and was first used with glass plates in the 1870s. Early photographers used the “wet plate” method. In the wet plate method, alcohols and ethers adhere silver halides to a glass plate. The silver halide mixture will eventually dry, but the photographer must expose and develop the film plate before this happens. This limited photography’s ability to be a portable medium.
When a negative is created using the dry plate method, it is exposed to light for a short amount of time. Exposure to light causes the silver halides to break down and form atoms of silver. When the film is exposed, only a few of the halides break down. After chemical developer is introduced, many more silver halides begin to form atoms of silver, until most of the atoms affected by the light have turned into black silver. A stop bath, usually a weak acid, stops this process. The final image is created on the negative with the fixer bath which dissolves the unaffected silver halides left on the film. These are washed away, leaving the image in black silver on the negative. Black and white film is panchromatic, which means that it is sensitive to all colors of light, so it must be handled out of the cartridge in complete darkness.
(Image from The Darkroom Handbook)
For Exposing the Film
For Developing the Film
1. Exposing the Film
2. Mixing the Chemicals
Concentrated Mix – I dissolved the entire package of powder into half a gallon (1900 mL) of hot water.
Standard Mix – I took half of the concentrated developer (950 mL) and mixed it with 950 mL of hot water to dilute the mix to the recommended proportions on the package.
Dilute Mix – I took half of the standard mix developer and added 950 mL of hot water diluting it to half its concentration.
3. Developing the Film
(The Woods Labs Chemistry Department Darkroom)
- I filled a shallow pan with water at 68°F
- I measured 450 mL of developer, stop, and fixer into beakers and placed these beakers into the shallow pan of water so the chemicals would remain at the proper temperature throughout the entire developing process.
- In complete darkness, I removed a section of exposed film, loaded it onto the film reel, and placed it a light-safe developing tank. (Once the film is in the light-safe tank, the darkroom lights can be turned on again and the film can be developed in normal light.)
- As soon as I began to pour developer into the tank, I started a stopwatch. Depending on the experiment, the film developed for 4, 8, or 12 minutes. The film was agitated for the first minute of development and then 15 seconds out of every additional minute of development.
- After the developer bath, the film was immersed in the stop bath for 5 minutes and then the fixer for 5 minutes. The tank was agitated intermittently during these baths as well.
- Once the film has completed the 3 baths, it can be removed safely from the tank. However, the film must be washed.
- To wash the film, I opened the tank and put it under a faucet of running water for 7 minutes. At the beginning of the wash period, I added a few drops of Kodak photo-flo to the tank to prevent water drops from beading on the film as it dried.
- Film was dried on a standard wire clothes hanger with a clothespin at each end to keep the film straight during drying time.
Experiment one: Develop three lengths of film in the same concentration of developer.
- one for the correct amount of time before applying the stop bath. (8 minutes) This length will serve as the control film that should produce the optimal contrasts between black and white with a complete grey scale when exposed.
- one overdeveloped 50 percent of the original time (12 minutes)
- one underdeveloped 50 percent of the original time (4 minutes)
Experiment two: Vary the concentration of the developer bath to try to achieve the contrast results in the control film from the previous experiment. Standard developer baths are created when the concentrated chemical mixture is combined with a set amount of water to create a usable developer. I will vary the concentration of the developer bath by changing the amount of water added to the concentrated chemicals in known quantities.
- Using the same time (overdeveloped) from experiment one, attempt to produce a concentration of developer that would be concentrated enough to create the same contrast effects of the control film.
- Using the same time (underdeveloped) from experiment one, attempt to produce a concentration of developer dilute enough to create the same contrast effects of the control.
- Develop two more lengths of film (one with the more concentrated developer and one with the more dilute developer to show what effects those solutions have on film under normal timing conditions – the time used to create the control film in the previous experiment)
Hypothesis: In this experiment I think that time and developer concentration would have a direct relationship in the form of a fixed ratio.
Observations and Data
Visual Data from Experiment One: These negatives were digitally scanned and are unmanipulated in any way. The effects produced here would appear if I developed them using photographic paper.
This negative was produced using the recommended time (8 minutes) at the recommended temperature (20 degrees celcius) with the standard developer mix. The shutter speed on the camera was set at 1/4 second. As this setting produced a black and white with a good range of grey tones, I shot the remainder of my film using this shutter speed. The image produced by this negative will act as my control for the rest of my experimentation.
Here is the same shot developed in the same strength developer for 50% less than the original time. After only spending 4 minutes in the developer, the silver halides have not had enough time to turn into black silver. This is most evident in the white cloth areas which should be completely black on the negative, but instead are only grey. As a result, the entire photograph is muddy with limited contrast.
This shot, developed for 12 minutes (standard time + 50%) with the standard strength developer is almost comparable in quality to the negative developed for 8 minutes. However the negative lacks a wide range of grey tones. This is especially evident when you compare the cloth folds from the control negative to the cloth folds produced by this negative. The longer developing time allowed too many silver halides to change into black silver.
Visual Data from Experiment Two:
Here is the image from the control negative again, just to refresh your memory. In experiment two, my goal is to attempt to produce this quality of contrast using different concentrations of developer with the same times from the first experiment.
This negative, like the second negative from experiment, was in the developer bath for 4 minutes. Because the developement time was 50% less than the control time, I mixed the developer so that it would be twice as concentrated. This negative is very dark and has dark specks visible in the lighter areas -- possibly from undissolved developer powder sticking to the film and preventing the dissolved developer from reaching the silver halides.
This negative stayed in the developer bath for 12 minutes. Because it was in the developer for the standard amount of time+ 50%, I diluted the standard developer mix so that it would be half as concentrated. Unlike the concentrated formula, this diluted formula produced a more desirable range of grey tones. While there is a difinitive black, there is not a difinitive white. However, more of the subtle shadowing in the folds in the lower left corner of the image are discernable, which could be a desirable outcome for some photographers.
Visual Effects of Concentrated and Dilute developer on negatives developed for 8 minutes:
Diluted developer: 8 minutes: A dilute developer produces a dark, muddy negative, indicating that there is a relationship between developer concentration and time in the developer.
Concentrated developere 8 minutes: The concentrated developer has eliminated almost all grey contrast in the negative. There are also black flecks on this negative similar to the first negative developed with concentrated developer.
To further assess the negatives, I used a 21 step sensitivity guide to determine the exact range of grey values in each negative. A value of one is equivalent to a pure black while twenty one is equivalent to a pure white ( in the printed negative). The values in between are greys increasing from dark to light. In the following table, an asterisk indicates that the negative will produce that value when printed.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 8 minutes standard * * * * * * * * * * * * * 4 minutes standard * * * * 12 minutes standard * * * * * * * * 4 minutes concentrated * * * * * * 12 minutes diluted * * * * * * * * 8 minutes concentrated * * * * * * * 8 minutes diluted * * * * * *
While the final results of my project did not turn out as I had initially predicted, I did learn some valuable lessons about the nature of photo chemicals. Generally, it is a bad idea to work with concentrated developer, as it will most likely ruin your negatives. An improper ratio of solvent to solute in developer alters the effectiveness of the developer. When it comes to developing film, more is not always better, and precision and patience are key. To achieve a black, a white and a wide range of greys, it is best to work with either the recommended chemical mix or set dilution of developer. The recommended chemical mix should achieve consistent desirable effects. A diluted mix could be used to coax subtle shadowing and detail out of a negative; however, the photographer would have to experiment more thoroughly with development times to get a full range of tones. I originally intended to print contact sheets of my negatives so that I could also evaluate them with the colorimeter, but after several failed attempts, I could not get this to work.
More information about working with black and white film in a darkroom.
[In August 2007, this link does not seem to be functioning] http://www3.telus.net/drkrm/index.html
Information on how to create your own darkroom.
A more in-depth explanation of the chemistry of black and white film.
Langford, Michael. The Darkroom Handbook. New York: Alfred A. Knopf, 1989.
Hedgecoe, John. The Photographer's Handbook, a Complete Reference Manual of Techniques, Procedures, Equipement, and Style. New York: Alfred A. Knopf, 1982.
Special thanks to Dr. Bordley and Woods Lab for the darkroom and photo chemicals, my dad for lending me most of the equipment for this archaic technology, Jamie Steele's project website for the picture of the Woods Lab darkroom, and my roommate, Katie Volz, for answering her cell phone at midnight and agreeing to stop by Wolf Camera in Nashville to get film for me on her way home the next day.