PROCESS MONITORING AND TROUBLESHOOTING
This section describes:
If you mix chemicals properly and use the correct settings for the process cycles, your processes should plot in control, and your minilab will produce high-quality customer orders-provided that your printer is set correctly. Deviations from standard conditions for the processing solutions, time, temperature, agitation, replenishment, filtration, wash water, or drying can cause processing problems. Deviations from normal conditions produce either under- or overdevelopment.
When the control plot shows a problem, you may also see the problem in customer orders. However, remember that customer orders reflect the entire system-i.e., the film process, paper process, and printer settings. For example, too much activity in the film process (overdevelopment of negatives), too little activity in the paper process (underdevelopment of prints), an incorrect printer setting, or a combination of these factors may cause the prints to be light. Checking only the control plots may not always isolate the problem, because using the wrong control strip or improperly stored strips may give false information. Therefore, to find the cause of any problem, check the control plots of your film and paper processes and customer orders.
Process Monitoring Terms The following terms are frequently used in process monitoring. Action Limits-The action limits are the boundaries of the desired operating range of the process. As long as the density values remain between the upper and lower action limits, your process is operating correctly. If a density value exceeds the action limit, it is an "early warning." You can still safely process customer work, but you should check for the cause of the shift and correct it. Aim Values-These are the values to which you compare your control-strip densities. To obtain aim values, read the reference-strip densities; then apply the correction factors to the density readings. Enter these values in the spaces provided on the left side of your control chart. Color-Balance Spread Limits-A color spread is the density difference between the two most widely separated densities of the HD - LD plot. If the process exceeds the color spread limit, stop processing customer work, and take corrective action. Control Limits-The control limits define the maximum tolerances that are acceptable for processing customer work. If any density value of your process plots beyond the control limit, the process is out of control, and results will be unsatisfactory for color, density, and/or contrast. Stop processing customer work until you find the cause and correct it. Control Strips-Precisely exposed strips used to monitor your process. Correction Factors-Numbers used to adjust the densities of the reference strip to obtain aim values. They are printed in the instruction sheet packaged with each box of control strips. Reference Strip-A control strip that is precisely processed by Kodak at standard conditions. A reference strip is packaged with each batch of control strips. To obtain aim values, measure the reference-strip densities and apply correction factors for that batch of control strips.
Process Monitoring Terms Tolerances and Limits-These are density variations permitted before you must take corrective action. These tolerances and limits include an aim-value adjustment tolerance and action and control limits. See KODAK Publication Z-99, Introduction to Color Process Monitoring, for more information on limits and adjustment tolerances. Tolerances and Limits for KODAK Control Strips, Process C-41 NA = Not Applicable Tolerances and Limits for KODAK Bleach Monitoring Control Strips, Process C-41Tolerances and Limits for KODAK EKTACOLORControl Strips, Process RA-4
Process Monitoring Methods How to Monitor Your Process To begin process monitoring you will need-
Control Strip KODAK Control Strips Are the Basic Control Material
KODAK Control Strips are available
for monitoring your processes. For a film process that uses KODAK
FLEXICOLOR Chemicals, use KODAK Control Strips, Process C-41,
and KODAK Bleach Monitoring Strips, Process C-41. For a paper
process that uses KODAK EKTACOLOR Chemicals, use KODAK EKTACOLOR
Control Strips, Process RA-4. A pre-processed reference strip
is packaged with each type of control strip, KODAK Control Strips, Process C-41
(35 mm)-Available
in 100-foot rolls of approximately 120 strips with cutoff notches
at 9Ѕ-inch intervals. The rolls are wound emulsion side
in, with the D-min end of the density scale toward the outer end
of the roll. Each strip contains 12 steps. KODAK Bleach Monitoring Control Strips, Process C-41-Available in 100-foot rolls of approximately 385 D-max patches. The rolls are wound emulsion side in. Use these strips to detect bleach problems that may cause leuco-cyan dye to form. Most Kodak films are not particularly sensitive to the presence of leuco-cyan dye, but some color-negative films (particularly some professional films and other-manufacturers' films) are sensitive to it.
To monitor the formation of leuco-cyan
dye, process a 5-inch length of the roll at least three times
a week.
Control Strips
KODAK EKTACOLOR Control Strips,
Process RA-4-Use these
strips to monitor Process RA-4 or RA-4ECM. They are available
in a box of ten moisture-resistant envelopes that contain five
strips each. Each control strip, reference strip, and box label
is marked with a code number. The code number identifies the strips
as part of a particular batch. Each box contains correction factors
for that particular code number. Use these factors to calculate
the aim values for this batch of strips. Each strip contains four
patches; measure them to obtain the density values for LD (low
density), HD (high density), BP (black patch), and D-min (unexposed
area).
Storing, Handling, ar Processing Control Strip Storing and Handling Control Strips Store unused control strips at -18°C (0°F) or lower. Handle unprocessed strips in total darkness. Remove only a day's supply from one package at a time; reseal and return the package to the freezer as quickly as possible. (Do not keep the package out of the freezer for more than 1 hour per day.) Store your daily supply of control strips in a lighttight container at room temperature. At the end of the day, discard any unprocessed strips that you removed from storage. Handle control strips by the edges to prevent fingerprints and surface damage. If film sticking, static marking, or moisture mottle occurs, allow the strips to warm up to room temperature before you process them. Store the reference strip in its envelope when you are not using it. |
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Processing Control Strips Each time you process a control strip, position it in the same location in your processor. Process a control strip-
For your film process, process a bleach monitoring strip three times a week* _______________________________ *Most current films are very resistant to the formation of leuco-cyan dye; however, some are sensitive to its formation. In addition, reduced process cycle times and lower replenishment rates have reduced safety margins. Be sure to monitor your bleach by processing a KODAK Bleach Monitoring Control Strip, Process C-41, three times a week.
Plotting Control Strip Densities
Plotting Control-Strip Densities
Create a control chart by using the KODAK Process Record Form Y-55 or similar graph paper. Follow the procedure given below. Your chart will look like the example shown at the right. For more information about setting up a control plot and using control strips, see KODAK Publication No. Z-99, Introduction to Color Process Monitoring. 1. Draw in the action and control limits given in the appropriate table on page 47 Use black for the action limits and red for the control limits. 2. Remove the reference strip from the box of control strips. If you removed the box from cold storage, allow the reference strip to warm up to room temperature before you remove it from its envelope (about 15 minutes). Exposing a frozen strip to warm, moist air can cause low readings, particularly in the higher density patches. 3. Measure the red, green, and blue densities in the center of each patch with a precision electronic densitometer. Do not move the strip as you make the density readings or you may affect the precision and repeatability of the measurements.
Plotting Control-Strip Densities
If you have several boxes of strips with the same code number, average the readings of all the reference strips. A code number on the box label and the reference and control strips identifies each batch. For the film process, measure the following densities of the reference strips. Set your densitometer to the transmission mode, and use the Status M filters. For the paper process, measure the following densities of the reference strip. Set your densitometer to the reflection mode, and use the Status A filters.
Plotting Control-Strip Densities 4. To calculate aim values, apply the correction factors supplied in the instruction sheet packaged with each box of control strips to the reference-strip densities. If you averaged the reference-strip readings from several boxes of the same code number, apply the correction factors to the average. These corrected density values are the aim values for that batch of control strips. Record them in the proper spaces in the left margin of Form Y-55.
5. Process a control strip and measure the same patches that you measured in step 3. For your film process, process a bleach-monitoring control strip, and measure the red- and green-filter densities of one D-max patch. 6. Calculate the variations from aim by subtracting the aim densities from your control-strip densities. Plot the variations on your control chart.
7. If any of the variations from aim plot beyond the action or control limits, process another control strip. If the second strip confirms the results of the first strip, determine the cause of the problem. The information on pages 56 and 57 will help you troubleshoot your process problems. 8. Whenever you take corrective action, process another control strip to confirm that the change that you made returned the process to control before you resume normal processing.
Changing to a New Batch of Control Strips Changing to a New Batch of Control Strips When you change from your current batch of control strips or bleach-monitoring control strips to strips with a different code number, make a crossover to confirm that both code numbers provide the same information. Be sure that your process is stable and in control before you begin using a new batch of control strips. 1. While you still have a week's supply of control strips of the current code, process one control strip from the new batch of strips with one strip from the current batch in three separate runs. 2. Read and record the densities of the processed strips. 3. Determine aim values for the new batch of control strips; follow steps 2 through 4 on pages 52 through 54. 4. For your current batch of strips, calculate the variations from aim by subtracting your current aim densities from the densities of the three strips. Plot the variations on your control chart. 5. For the new batch of strips, calculate the variations from aim by subtracting the new aim densities (calculated in step 3) from the densities of the three strips. Plot the variations on your control chart. 6. Calculate the differences between the variations from aim of the current strips and the new strips. Average these differences, and then divide the result by 2. 7. Depending on the sign of the average difference, adjust the aim values for the new batch of strips by adding or subtracting the results from step 6. The amount of the adjustment should not exceed the aim-value adjustment tolerances given in the appropriate table on page 47. If the adjustment is greater than the tolerance, determine the cause. Check your calculations, densitometer, and control strips. 8. Record the new aim values and the code number of the new batch of strips on your control chart, and begin using the new strips.
Troubleshooting Troubleshooting Your Process When one or more process parameters exceeds the control limits, stop processing customer work until you find and correct the cause of the problem. It is important to become familiar with control-chart patterns and cause-and-effect relationships. Control-chart patterns can generally be separated into three categories. High Activity-the process is out of control with process parameters plotting above aim. This condition can be caused by:
Low Activity-the process is out of control with process parameters plotting below aim. This condition can be caused by:
High D-min-this condition can be caused by:
Troubleshooting Check your control chart to determine if the process drifted out of control slowly or suddenly. Slow Drift-An out-of-control condition that has occurred slowly over a long period signals a problem such as: Improper replenishment-caused by a replenishment rate that is not set correctly a defective replenisher pump, or an incorrectly mixed replenisher. Evaporation or oxidation-caused by low utilization or air drawn into the processing solutions by a bad pump or a poorly placed ventilator fan. Contamination- caused by photographically active materials that leach slowly into the solutions and cause the process to drift out of control. The contaminant may be in any material the solutions contact, such as the filters, plumbing, etc. Incorrect mixing- if you suspect that the problem was caused by replenisher solution that was mixed incorrectly, mix a new batch of replenisher to see if a fresh mix gradually corrects the problem. Sudden Change-Causes of a sudden out-of-control condition are: Control strip- using a control strip with a different code number or a strip that has not been properly stored can indicate a sudden process change. Densitometer-if your densitometer is not working properly or is out of calibration, the density readings will be wrong. This can falsely signal that there was a process change. Time or temperature- check that the time and temperature were set correctly particularly if it is easy for operators to accidentally change the settings. Contamination-very small amounts of fixer or bleach-fix can contaminate the developer tank solution and cause a large density and color shift If your developer replenisher is contaminated, the density and color shift will occur gradually (depending on how often the tank solution is replenished). Mixing- if the sudden change occurs after you have mixed a fresh tank solution, check that it was mixed correctly. Aim values-check that you compared the control-strip densities with the correct aim values. Note: When you troubleshoot a problem, first check the easiest and most obvious causes; then check the more difficult and less likely causes. For complete information on diagnosing your processes, see the control-chart examples in KODAK Publications No. Z-130 Using KODAK EKTACOLOF! RA Chemicals, and Z-131, Using KODAK FLEXICOLOR Chemicals.
Appendix APPENDIX Simplified Metric Conversion Tables Many laboratory measuring devices are calibrated in metric units. You can use the following tables to convert U.S. units of volume, length, and weight to metric units. Do not use these tables to convert from metric to U.S. units. Accuracy of the tables is ± 1 percent. To use the tables for numbers from 1 to 9, find the number you are converting from at the top of the table; the metric measurement is the number at the top of the column below the U.S. measurement (e.g., 4 U.S. gallons = 15.1 litres). For numbers greater than 9, obtain the number you are converting from by using a combination of one number from the left side of the table and one number from the top; the metric measurement is the number where the two U.S. measurements intersect (e.g., 21 U.S. gallons = 79.5 litres). U.S. Gallons to LitresU.S. Fluidounces to MillilitresInches to Centimetres Ounces to Grams
Appendix Temperature Conversion
To convert a temperature from one
unit of measure to another, use the following tables. Find the
temperature you are converting from in the second column; if you
are converting to degrees Celsius, read the number from the left-hand
column. If you are converting to degrees Fahrenheit, read the
number from the right-hand column. For temperatures not shown in the tables, use the following formulas: 1. To convert to degrees Celsius, add 40 to the Fahrenheit temperature. Then divide by 1.8; subtract 40 from the result. 2. To convert to degrees Fahrenheit, add 40 to the Celsius temperature. Then multiply by 1,8; subtract 40 from the result.
Index INDEX Chemicals and Chemical Handling Characteristics of chemical concentrates; 13 to 14 Chemical Handling; 10 to 11 Labeling; 10 Mixing; 12 Safety; 10 to 11 Solution effects; 3 to 5 Terms; 2 Cleaning tanks and racks; 18 Compensating for evaporation; 16 Contamination; 12 Conversion tables for metric/ U.S. measurements; 59 to 60 Effluent Characteristics; 19 Disposal; 19 to 20 Management; 21 Reduction; 20, 21 KODAK Chemicals; 6 to 9 Sizes available (in U.S. and Canada); 7, 9 KODAK RELAY Program; 20 Mixing equipment; 12 Processing solution function; 3 to 5 Silver recovery; 22 Solid waste disposal; 22 Storage; 15 Ventilation; 11 Processing Cycles for KODAK Chemicals Agitation; 3, 4, 25, 35 Bleach; 3, 27 Bleach-fix; 4, 34 Converting to EKTACOLOR PRIME Chemicals; 37 Converting to Process RA-4ECM; 41 Adjustment factors, Process RA-4ECM; 43 Developer: 3, 34, 37 Converting to EKTACOLOR PRIME Developer Replenisher; 37 Developer regeneration; 39 Drying; 28, 35 Filters, solution; 28, 35 Fixer; 4, 27 Leuco-cyan dye; 3, 27, 49, 51 Process steps and conditions KODAK CREATE-A-PRINT 35 mm Enlargement Center; 36 Process C-41; 26 Process C-41B; 24 Process C-41RA; 25 Process RA-4; 31 Process RA-4ECM; 32, 33 Replenishment rates Film process; 24 to 26, 27 Paper process; 31 to 32, 33 Retained silver; 27, 34 Solution filtration; 28, 35 Stabilizer; 5, 27, 34 Utilization; 29, 30, 31 to 33 Wash water; 5 Wash rates; 28, 34 Process Monitoring and Troubleshooting Action limits; 46, 47 Aim values; 46, 54 Aim-value adjustment tolerances; 47 Bleach monitoring; 47, 49, 54 Color-balance spread; 46, 47 Control limits; 46, 47 Control strips; 46, 49 to 50, 51 Changing batches; 55 Plotting densities/variations from aim; 52 to 54 Processing frequency; 51 Reading; 52 to 54 Storage and handling; 51 Correction factors; 46, 54 Densitometer; 48 Filters: 48, 53 Reference strips; 46, 52 to 54 Tolerance limits; 47 Troubleshooting; 56 to 57
More Information MORE INFORMATION If you have questions about Kodak chemicals, call the Kodak Customer Assistance Center-in the U.S., call (800) 242-2424, extension 68, between 8 a.m. and 8 p.m. (Eastern time), Monday through Friday; in Canada, call (800) 465-6325, between 8:30 a.m. and 5 p.m. (Eastern time), Monday through Friday. Kodak also produces publications to assist you with information about Kodak products, equipment, and methods. The following publications are available from dealers who sell Kodak products, or you can order them directly from Kodak through the order form in KODAK Publication No. L-1, KODAK Index to Photographic Information. To obtain a copy of L-1, send your request with $1 to Eastman Kodak Company, Department 412-L, Rochester, New York 14650-0532. J-2A Health, Safety, and Environmental Emergency Card J-4 Safe Handling of Photographic Chemicals J-4S The Prevention of Contact Dermatitis in Photographic Work J-20 Disposing of Minilab Effluent J-36 Choosing the Right Chemicals for Your Minilab J-55 Disposal and Treatment of Photographic Effluent-In Support of Clean Water Y-55 KODAK Process Record Form Z-99 Introduction to Color Process Monitoring Z-130 Using KODAK EKTACOLOR RA Chemicals Z-131 Using KODAK FLEXICOLOR Chemicals This publication is printed on recycled paper that contains 50 percent recycled fiber and 10 percent post-consumer material. Consumer Imaging EASTMAN KODAK COMPANY ROCHESTER, NY 14650
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