A sensitometric control strip should be processed as a minimum-at the beginning of a production day (or shift), before any production is processed, and before shutdown. You should process a control strip just before an important mission, or a special-interest film is processed.

To expose and process a control strip, you should take the following steps:

1. Take the film (in a lighttight container) and place it next to the sensitometer.

2. Turn on the sensitometer and allow it to warm up for a minimum of 15 seconds.

3. Turn off the room lights.

4. Place the film emulsion-side down on the sensitometer and lower the platen to make your exposure.

5. When hand processing or using a rotary tube type of processor, load the control strip on the reel. When machine processing, replace the film in a lighttight container. Turn on the room lights and turn off the sensitometer.

6. When a roller transport processor is used, check the speed, temperatures, and the proper operation of all systems.

7. Stick the film into the processor so the lightly exposed end of the film enters the machine first. When hand processing or using a rotary tube type of processor, process normally.

Figure 10-27. Control strips read from center of each step with emulsion facing up.