The tray method is used primarily for processing only a few sheets of film. With a lot of experience, you can process as many as 6 to 12 sheets of film in a tray at one time. You will find it easier to work with only a few sheets of film at a time, and repeat the process, than to start all the sheets at the same time and damage them.

The tray processing method described here has proven satisfactory under most conditions for processing one sheet of film at a time. You should use this method as described and develop the necessary skill using this procedure before you attempt to use variations.

The trays should be considerably larger than the film being processed; for example, 4x5 film should be processed in 8x10 trays, 8x10 film in 11x14 trays, and

11x14 film in 16x20 trays. Ideally, the trays should be arranged in a shallow sink that contains temperature-controlled circulating water. The trays should be arranged with the developer to your left as you face the trays. The stop bath goes next to the developer, followed by the fixer and the wash tray.

In all Navy imaging facilities, it is standard procedure when processing film (or prints) by hand to work from left to right.

Rinse the trays with fresh water as a precaution against contamination, and prepare the solutions. When the solutions are ready, place the exposed film holder to be unloaded on a clean, dry area of the workbench near the developer. Set the timer for the correct developing time, and place it in a convenient location near the processing solutions. Then, if you are processing panchromatic film, turn out all the lights. If you are processing monochromatic or orthochromatic film, you can use a suitable safelight.

Remove one sheet of film from the holder and submerge it quickly, emulsion-side down, into the developer. Then immediately turn it over (emulsion-side up) and slide it back under the surface of the developer quickly, and agitate it vigorously to eliminate possible air bubbles. The surface of the film must be wetted quickly and evenly; otherwise, developing marks may result. Start the timer just before the film is placed into the developer.

During tray development, the tray should be rocked continuously to provide constant agitation. Be careful that the tray rocking is not too fast and that it is varied at intervals; for example, first front to back, and then side to side to avoid patterns of uneven development caused by regular waves.

CAUTION

Do not allow your fingernails to touch the film emulsion at any time.

Tray development involves constant agitation, and development time is usually about 20 percent less than if the same film were being developed with intermittent agitation. When tray agitation is done very slowly, the agitation should be considered intermittent and the developing time adjusted accordingly.

When the timer rings, remove the film from the developer, drain it from one corner, and submerge it in the stop bath. Agitate the film in the stop bath for about 5 seconds; then transfer it to the fixer. You must agitate the film vigorously in the stop bath and initially in the fixer because gases are released in these solutions and there is danger of air bubbles forming on the film surface. If you allow these air bells, or bubbles, to form, they may cause dark spots. This is due to the continued action of the developer beneath the bubbles. Agitate the film in the fixing bath for a few seconds and then the safelights or the white lights may be turned on. Continue agitating the film until it loses the cloudy or creamy appearance. Note the time required for this change to occur because it is just half the total required fixing time. Agitate the film several times during the second half of the fixing time. After the film clears, continuous agitation is not necessary.

After fixing is completed, transfer the negative to the wash water and continue to agitate it unless a regular film washing tank or tray is available. After washing is complete, the film should be treated in a wetting agent and dried.

As stated earlier, with experience you can process several sheets of line copy film at a time in a tray. When processing several sheets in a tray at once, there is an added step. This is a predevelopment rinse in clean water that should be at the same temperature as the rest of the processing solutions. The predevelopment rinse is located to the left of the developer. Its purpose is to prevent the films from sticking together in the developer.

The procedure for processing more than one sheet of line copy film at a time is the following:

1. When the solutions are ready, place a dry, dust-free paper or cardboard on the workbench near the predevelopment rinse. Place the exposed film holders near this clean working space.

2. Set the timer.

3. Turn out the lights.

4. Remove one film from its holder and place it, emulsion-side down, on the clean paper. Remove the second film and place it, emulsion-side down, on top of the first. Continue until all the film is placed in a loose pile on the space provided for them.

5. Pick up the film on top of the pile with your left hand (keep it dry until all films have been placed in the water), drop it, emulsion-side down, into the water, and immerse it quickly with your right hand. Pick the film up immediately, turn it over, emulsion-side up, and push it back under the solution. Place the wet film, emulsion-side up, at one end of the tray. Immerse the next film in the same manner. Stack it on top of the first film, and continue with this procedure until all the films are stacked in a pile at one end of the tray. Your left hand should follow the last film into the tray to assist in the agitation of the films.

Wet film may be handled with wet fingers. However, be extremely careful to KEEP WET FINGERS OFF DRY FILMS. Slight pressure with the balls of the fingers is not harmful to a wet emulsion unless it has swollen excessively.

The films should be agitated or shifted constantly to prevent the individual sheets from sticking together. Agitation is accomplished by moving the first film from the bottom of the stack and placing it on top or by starting a new stack at the other end of the tray. Continue agitating the films from bottom to top until they become completely saturated with water-about 1 or 2 minutes is sufficient. After the emulsion is completely saturated, the danger of films sticking together is no longer a problem.

6. Remove the films, one at a time, from the predevelopment rinse and immerse them in the developer. Place the films in the developer, emulsion-side up; slide them under the surface of the solution quickly, and agitate them vigorously to eliminate possible air bells. Start the timer just before the first film is placed in the developer. Use your left hand to remove all films from the water, and be careful not to get the water contaminated with developer. Your left hand should follow the last film transferred from the water into the developer to help with the agitation.

It is important for you to locate the first sheet of film placed in the developer quickly. To do this, align the long dimension of all other films at a right angle to the first sheet placed in the developer.

The films are immersed, emulsion-side up, in the developer to reduce greater damage that would occur if the emulsion, already softened by presoaking, were allowed to come in contact with the bottom of the tray. Be careful not to dig or drag the comer or edge of a film into the emulsion surface of the film below it. Do not allow your fingernails to touch the emulsion at any time. Stacking films by aligning their edges against the sides of the tray helps to reduce scratches and abrasions.

7. Agitate the films constantly, not by rocking the tray, but by moving each film from the bottom of the stack and placing it carefully on top, and pressing it down gently to assure a flow of solution over its surface. Continue this procedure until the developing time is up.

Figure 10-11. Sheet film hangers arranged for tank processing.

8. When the timer rings, remove all the films from the developer in the same order that they were placed in the developer, and submerge them in the stop bath. Your right hand should go into the stop bath with the first film and stay there to handle each film as it is transferred from the developer by your left hand. Use your left hand only for transferring the film to avoid contamination of the developer or spotting of the film. A few drops of developer will not affect the stop bath or the fixing bath, but a few drops of either of these solutions could rum a developing solution.

9. After all the films have been shifted several times in the stop bath, they should be transferred individually to the fixing bath or hypo. Shift the films several times in the fixing bath, agitating them vigorously. Then safelights or the white lights may be turned on. Continue shifting the films until they lose the cloudy or creamy appearance. You must shift the films several times during the second half of the fixing time, but continuous agitation is not necessary.

10. After fixing is completed, transfer the negatives to the wash water and continue agitation unless a regular film washing tank or tray is used. The negatives also may be put in regular film hangers for washing.

11. Treat the film in a wetting agent and dry it.