Film Processing Basics
Film processing amounts to a series of well-defined steps. The single most important regarding film processing is consistency. Each step should be exact, and repeated exactly. This consistency becomes easier with experience and repetition. There will be mistakes made, when film does not come out as expected. Consistency makes it much easier to diagnose problems.
Development Controls Contrast
Perhaps the single most important concept to remember about processing film is that development controls contrast. Development does not change density—that is controlled by exposure. Thin negatives are usually cause by underexposure, not too little development.
The variables in processing film are developer dilution, time, temperature, and agitation. Each of these alone can affect contrast. Simply put, the more of any of these, the more contrast.
Different dilutions of a developer will give different results, with more dilution yielding less contrast. The dilution of the developer will also affect the time. For example, for Ilford's HP5+ film, using Kodak D-76 developer and a stock (undiluted) solution, 7 1/2 minutes is recommended. At a 1:1 dilution, the time changes to 11 minutes, and at a 1:3 dilution, 22 minutes.
The time of the development step (when the film is in the developer) depends on the film/developer combination. Different films require different times in the same developer. Likewise, a particular film will have different times in different developers. There are various sources for determining what time should be used. Recommended is to start with the manufacturer's recommendation. Another good source (that is rather comprehensive) is the Massive Development Chart, at Digital Truth Photo (http://www.digitaltruth.com).
Whatever source is used, pay careful attention to the results you are getting. Your development time may need to be adjusted, either more or less. Look for consistent results, particularly on well-exposed scenes that contain a wide range of tones. The contrast should reflect the range of tones. If there is too little contrast, the time may need to be increased, and conversely, to much contrast, the time may need to be decreased. That being said, the best path for a beginner is to stick with the same film/developer combination until good, consistent results are obtained. Reducing the amount of variables involved makes troubleshooting musch easier.
Times for the rest of the steps are consistent, and do not (usually) depend on the film. Essentially what should be done is to do each step for at least as long as recommended, and maybe a little longer. (These times are given in the Process section).
Temperature is critical when processing film, especially during development. Film development, for black-and white, occurs at 68°F, or 20°C. Even a slight variation, a degree one way or the other, will alter the contrast. In general, the warmer the developer, the more contrast (and grain). Careful measuring and a good thermometer goes a long way here.
Consistency also plays a big role. Use the same thermometer. In a lab situation, it may well be the case that there are several thermometers about. If they are not all similarly accurate, using different ones will will mean inconsistent results. If a thermometer is off by a degree or so, and always off by the same, development can be adjusted to compensate.
Agitation replaces used, more exhausted chemistry with fresher. The chemistry in or on the film will become exhausted quite quickly, so the film must be agitated to refresh. This occurs in as little as one minute, where the chemistry is not doing much at all. Agitation consists of inverting the tank, using both hands. Agitation needs to even and consistent, and as may be expected, is most critical during the development step.
The more agitation, the faster the reactions occur. So, during the development step, the more agitation, the more contrast, and the more grain. To control, contrast, agitation needs to be done in a steady, even manner. The normal agitation routine for the development step is continuous for the first 30 seconds, then 5 seconds every 30 seconds until the time is up. Alternately, many use a cycle of 10 seconds every minute.
The tools described below are needed for processing roll film.
- 1. Film
- 2. Complete tank and reel (see also loading film)
- 3. Scissors
- 4. Church key to open cassette (35mm)
- 5. Photographic Thermometer
- 6. Timer
- 7. Graduate(s)
These are covered in much greater detail in the section The Process. They are set out here as an overview.
- 1. Load film onto reel, place in the tank.
- 2. Determine development time for the film, according to the developer and dilution, and set timer for that length.
- 3. With the outer lid off, pour the developer into the tank. Do this rapidly, tilting the tank so air does not get trapped. Start the timer.
- 4. Develop for set time, agitating intermittently.
- 5. When time is up, pour out developer and pour in stop bath. Agitate continuously for 1 minute.
- 6. Pour out stop bath, pour in fixer. Agitate continuously for 10 minutes.
- 7. Pour out fixer. Open tank (so you can see the reel – both lids), and begin first wash: 5 minutes or fill and dump tank 10 times.
- 8. After first wash, fill tank with Hypo-Clear (wash aid). Close up tank and agitate continuously for 2 minutes.
- 9. Dump wash aid. Begin second wash: 10 minutes or fill and dump tank 20 times.
- 10. After second wash, fill tank with wetting agent (Photo-Flo), and agitate gently for one minute.
- 11. Remove reel from tank. Snap it into sink a couple of times to remove excess wetting agent, then hang in film cabinet to dry. Weight the bottom of the roll with a clothespin.