The process most commonly used for reproducing construction drawings by the Navy is the DIAZO or AMMONIA VAPOR PROCESS. Basically, this process produces prints with a white background and blue or black lines after exposure to light. These prints are then dry developed with ammonia vapor. This process uses aqueous ammonia as a developing agent with water vapor as the carrying agent, causing the paper exiting from the chamber to carry residual ammonia vapor with it. In the diazo process, the ammonia chest is saturated with water vapor at all times to help eliminate the toxic ammonia vapors.

Diazo process reproduction machines are made by several manufacturers, such as Blu-Ray Inc. and General Analine Film Corp. (GAF). Machines formerly made by GAF were called Ozalid. The machines presently made are no longer called Ozalid, only labeled GAF. However, old Ozalid equipment is still serviced and repaired by the GAF Corporation.

The basic difference between the various types of diazo machines is the size of paper that they can accommodate. Paper that is 9 in. wide can be used on the smallest machine, and paper that is 54 in. wide can be used on the largest machine.

The Blu-Ray Model 842 Whiteprinter, shown in figure 3-61, has most of the capabilities of larger diazo process machines. It is ideally suited for use in battalion engineering offices, because it is easy to set up and is easily moved. It is very simple to operate and easy to maintain.

It is important that all EAs thoroughly under-stand the manufacturers instructions covering the operation and maintenance of the Blu-Ray reproduction machine before attempting to use it. Keep a current file for all reference material available for use by the operators. The machine should be located as close as possible to an electrical outlet that supplies adequate power. (Electrical specifications are given in the operation manual.)

After the machine has been assembled and set up according to the manufacturers instructions, the machine must be placed on a level surface, such as a table or a desk. This is very important for proper ammonia drainage and adequate support for the feet on the bottom of the machine.

Figure 3-61.-Exploded view of the Blu-Ray Model 842 Whiteprinter.

The ammonia supply bottle must be placed below the machine so that there will be a short, direct, and unkinked run of the large ammonia discharge tube. Only the proper aqueous ammonia, as recommended in the operation manual, should be used. Use only fresh ammonia and change it at least once a month for best operation. NEVER reuse the discharged ammonia.

Room temperature is important. Blu-Ray manufacturers recommended a room temperature of 70F be maintained. A drop in room temperature will cause condensation in the chest, giving wet prints and may, if excessive, jam the developer.

The Blu-Ray is equipped with an ammonia chest heater, which has an independent heater switch. The heater is used to activate the ammonia vapor to improve development when it is necessary. This may be true especially with long, continuous machine operation.

The machine must be kept dust-free and clean. Dust is an abrasive material that can wear out the Teflon gate strips in the developer section, as well as other moving parts.

OPERATION. A pilot-lighted switch marked POWER on the instrument panel turns the Blu-Ray machine on and off. When it turns the machine on, it actuates the main drive motor and the ammonia pump motor and fan, and it lights the fluorescent tubes.

A pilot-lighted switch marked HEATER on the instrument panel manually turns the heater on and off.

Two knobs on the instrument panel marked SPEED and DIRECTION manually will give a stepless speed range from 0 to 12 ft per min in both directions.

To select the desired speed of operation, manually turn the knob marked SPEED to a number that experience has shown to be proper for the type of paper being printed.

The knob marked DIRECTION has a forward and reverse setting. Keep this knob at forward setting at all times. Use the reverse setting only when the paper is jamming and must be instantly removed. This knob can be snapped from forward to reverse while the machine is running. The Blu-Ray may be turned on and off AT ANY TIME. THERE IS NO WARM-UP OR COOL-DOWN PERIOD REQUIRED FOR THIS MACHINE. Just turn on the power switch, make your print, and turn the machine off. This is recommended for longer machine and lamp life. Making prints is extremely simple. Place your original tracing or transparency, face up, on the sensitized reproducing paper, chemical (yellow) side up. Adjust the leading edges of both papers so they are even, uncurled, and uncreased. THIS IS IMPORTANT! Place the two adjusted sheets on the feed table and gently feed them evenly into the printer entrance WITH THE GRAIN of the sensitized paper (see package for grain indication) until they are engaged between the rubber belts and the glass cylinder.

If for any reason the above described entrance of the paper to the printer is erratic, creased, wrinkled, or uneven, turn the direction knob to reverse and the papers will come out of the printer.

As the original and printed sensitized paper exits from the printer over the top of the glass cylinder, manually separate the sensitized paper from the original tracing.

Turn the sensitized paper up and into the entrance of the ammonia developing chest. The finished print will exit from the top of the machine.

If your print is too light, turn the speed knob to a higher number; if too dark, turn to a lower number.

The interior of the ammonia chest of the Blu-Ray machine is readily accessible for inspection or removal of jammed paper. Using finger catches on the top of the machine, lift up the top cover, and the upper chest panel will be exposed. (Before opening, SEE WARNING below.) Two sliding door latch-type fasteners hold the upper chest panel in its closed position. Slide these door latches toward the center of the machine, and open the upper chest panel up and back, exposing the interior of the ammonia chest.