The next step is to develop the film. There are two general processes which can be used. The more efficient is based on the time and temperature theory. The temperature of the solution determines the length of time the film is to be left in it. This method requires a lightproof tank, and is commonly called the tank method. The solutions may be changed without removing the cover.
A less efficient method is tray development. Simpler equipment is required, but practice is necessary before control can be achieved. The same developer that will be used later for developing the print may be used when developing the film in a tray.
Either a stainless steel or bakelite adjustable tank may be used (fig. 271). The loading of the tank must be done in complete darkness for panchromatic film. Orthochromatic film (Verichrome or Plenachrome) may be exposed to a dark red safe-light, such as one with a Wratten Series 2 filter. Read the instructions in the film package concerning the proper safelight. These instructions will also mention that total darkness is necessary, if that is true. To be absolutely sure, ask at the photographic supply store when you buy film. Practice loading the tank in bright light with a roll of waste or developed film. Read the instructions supplied with the tank and follow them very carefully. The commonest tank has matched spiral grooves at the top and bottom of the reel. Hold the film between thumb and forefinger of the right hand and the reel in the left hand. Thread the beginning of the film into the groove and push gently. If the grooves are wet the film will stick. Feed the film into the reel until it is completely threaded. When you become practiced at loading with the dummy film in bright light, try a roll in the darkroom. Before starting be sure to place the tank, the cover, and the reel in a convenient position for locating in the dark. When the film is loaded, replace the cover, making sure that it is secure. The white light may now be turned on.
The standard chemical formula for tank development is Eastman Kodak's D-76. The prepared developer, in powder form, is sold in any photographic supply store. The 1-quart size will be sufficient for most tanks. Mix according to the directions on the package.
If the prepared developer is not available, the formula may be mixed from the basic chemicals. Doing so wastes a great deal of time and saves no money, unless quantities of 5 gallons or more are mixed. If mixing from the basic chemicals is necessary, mix the following chemicals in the order given:
Water (about 125°F. or 52°C).
Sodium sulphate, desiccated
Cold water to make
Elon is Eastman's name for a solution also known commercially as metol. The two are identical for all ordinary uses.
(1) Pour the completely mixed developer into a 32-ounce graduate and check the temperature. It may be used at any temperature from 65° F. to 75° F. If it is above 75° F., cool it for immediate use. Set the graduate in a sink of cold water and stir the developer slowly. When the proper temperature is reached, pour as much developer as your tank will hold into the closed tank through the opening provided in the top. Make a note of the time at this moment. Agitate the film by rotating the knob on top of the tank or by the use of whatever device is provided. Do not agitate violently and do not turn constantly in one direction.
(2) ;The time of development at 65° F. is about 20 minutes. As the temperature increases, the time decreases, until, at 75° F., only about 12 minutes are required. These times are approximate. If the film has been taken under very poor light conditions, increase the time 2 or 3 minutes.
(3) ;When sufficient time has elapsed, pour the developer back into the graduate. After completing the next two processes, pour the developer back into the bottle and stopper it tightly for future use. It may be used for 15 or 20 rolls of film. Increase the time 2 minutes for each roll after the tenth.
(4) ;The next solution needed is the short stop. It must be prepared before starting development. The purpose of this solution is to stop development immediately. The solution is made by adding 30 drops of 28 percent acetic acid to 32 ounces of water. Do not necessarily mix 32 ounces. Mix only as much as your tank will hold. It must be at the same temperature as the developer. Use this solution only once. Pour the correct quantity into the tank the moment the developer has been poured off. Agitate gently for 5 minutes. Pour off the short stop.
(5) The third and final solution is the acid fixing bath, or hypo, which should also be prepared before developing starts. It should be about the same temperature as the other solutions, but may be some 5° cooler. Once again the prepared formula is available wherever photographic supplies are sold, but it may be mixed from basic chemicals. Mix the following chemicals in the order given:
Soldium sulfite, desiccated ..
Acetic acid, 28 percent ......
Boric acid crystals
Cold water to make
(6) ;Crystalline boric acid should always be used, as powdered boric acid is very hard to dissolve. Pour the hypo into the tank and agitate for 2 minutes. Leave the tank closed for 8 more minutes. Remove the lid and pour the hypo back into the bottle or graduate. This hypo may be used for another roll of film if used within the next day or so. Otherwise it should not be used for film again but should be saved for fixing prints. Place the film, still in the tank, under running water of about the same temperature as the other solutions. If the water is lower than 60° F. or higher than 75° F., it may not be used directly from the tap. Cool or heat a large vessel of water to the proper temperature, and use it for washing the film. Pour the tank full of water of the correct temperature, and let it stand for about 5 minutes. Pour it off and pour the tank full again. Let the second bath stand for about 5 minutes. Continue this until the bath has been changed 7 or 8 times, letting the film soak in each bath for about 5 minutes.