Control strips and reference strips Color  densitometer Control  charts Processing   records   of   mechanical   and chemical  variables MONITORING MANUALS Since the details of the monitoring procedure change  with  each  color  process,  process-monitoring manuals, such as Kodak’s Z-series, are necessary supplements  to  a  color  process-monitoring  system. The monitoring manuals describe the process, the specific control strip to use, the steps to read, the calculation of reference values and control values, the specific   plot   patterns,   and   the   plot-pattern interpretation. CONTROL  STRIPS Control strips for color process monitoring are supplied   by   the   manufacturer   of   the   color light-sensitive material or process. The most common control strips used in Navy imaging facilities are Kodak  process-control  strips.  Like  black-and-white control strips, color control strips have a series of neutral-density   steps.   Process   monitoring   relies primarily on the measurement of densities of the steps. It is important to measure the minimum density and,  usually,  two  steps  representing  intermediate tones.  Monitoring  D-max  is  also  desirable  for  color reversal film and paper. The relationship among the three color measurements of a step is used to monitor color balance. The difference in the readings from the two steps (HD-LD) provides measurements of red, green, and blue contrast. Control strips must be stored at 0°F (-18°C) or lower   to   minimize   color   shifts.   The   strips   are stabilized  and  given  an  expiration  date,  so  they provide  a  reliable  tool  to  monitor  processes.  The strips should be removed from the freezer, one at a time, as they are needed. A number of control strips from each control-strip batch are processed by the manufacturer. One of the processed strips is included with each package of control  strips.  These  processed  strips  are  called reference strips. The reference strips provide a means for imaging facilities to determine a process standard in terms of densitometer readings. By reading these reference strips and applying correction factors (supplied with the control strips) to specified  steps,  you  can  determine  the  initial  reference, mean, or aim values. ESTABLISHING PROCESS-MONITORING PARAMETERS The first time color process monitoring is used or the first time a process is started up, the steps for establishing  a  process-monitoring  system  are  as follows: 1.   Ensure   that   chemical   and   mechanical specifications   are   met.   These   include   mixing procedures,  processing  temperatures,  times,  and  so forth. 2.  Determine  initial  reference  values  for  the particular code of control strips you are using. This generally consists of reading the reference strip on the densitometer,  recording  the  densities,  and  adding  or subtracting correction factors (supplied with control strips). (See fig. 2-16.) When available, average the reading of several reference strips to minimize the effects of variability. NOTE:  Be  sure  that  the  reference  strips  and control  strips  you  are  using  have  the  same  code number. A code number is assigned to each emulsion batch,  and  this  code  number  changes  with  each emulsion  batch  manufactured. 3. Process five control strips, one in different production runs. You should always feed the strip in a continuous processor with the low-density end first. The end of the film with the low-density steps is indicated with a dimple on the film. You should also feed the control strips into the processor at the same location of the feed tray. It does not matter whether you feed from the center, the far-right side, or the far-left side. It is important for you to process the control strips consistently to reduce variability. 4.  Read  the  red,  green,  and  blue  densities  of the   specified   control-strip   density   steps   on   the densitometer  and  average  the  values. 2-31