GMI Process Control and Documentation 3 — Questions and Answers
Question 1: Which measurement geometry is recommended by ISO 13655 for measuring printed color on coated substrates?
- 0°/45° or 45°/0° (Correct answer)
- d/8° with specular component included (SPIN)
- d/8° with specular component excluded (SPEX)
- 45°/0° with UV included
Correct answer: 0°/45° or 45°/0°
ISO 13655 recommends 0°/45° or 45°/0° geometry for reflectance measurement of printed materials to minimize the influence of surface gloss.
Question 2: In SPC (Statistical Process Control) for printing, what does a point falling outside the control limits on an X-bar chart indicate?
- Normal process variation within expected range
- A potential special cause of variation requiring investigation (Correct answer)
- The sample size is too small to be meaningful
- The process is perfectly centered on the target
Correct answer: A potential special cause of variation requiring investigation
A point outside control limits signals a special cause of variation—an unexpected event that warrants investigation and corrective action.
Question 3: What is the purpose of a make-ready sheet in offset printing operations?
- A sheet used to verify color accuracy for customer approval
- A test sheet used during press setup to achieve correct ink/water balance and registration before production (Correct answer)
- A substrate sample provided by the paper manufacturer
- A document listing all chemicals used during press wash-up
Correct answer: A test sheet used during press setup to achieve correct ink/water balance and registration before production
Make-ready sheets are printed during press setup to adjust ink density, registration, and ink-water balance before pulling production-quality sheets.
Question 4: A PDCA cycle in quality management stands for:
- Print, Develop, Check, Approve
- Plan, Do, Check, Act (Correct answer)
- Prepare, Deploy, Control, Audit
- Process, Document, Calibrate, Assess
Correct answer: Plan, Do, Check, Act
PDCA (Plan, Do, Check, Act) is a continuous improvement cycle used in ISO quality systems to systematically solve problems and improve processes.
Question 5: In graphic arts, what does the term 'register' refer to?
- The sequential numbering of job orders in the management system
- The precise alignment of multiple color separations printed in sequence (Correct answer)
- The calibration record of densitometer measurements
- The storage location of color profiles on a prepress workstation
Correct answer: The precise alignment of multiple color separations printed in sequence
Register refers to the accurate positional alignment of multiple ink layers so that each color prints in its correct relative position.
Question 6: Which type of proof is considered the most accurate contract proof for predicting press output?
- A digital display soft proof on a calibrated monitor
- An inkjet proof produced using an ICC profile matching the target press condition (Correct answer)
- A blueline proof made from film
- A photocopy of the original design file
Correct answer: An inkjet proof produced using an ICC profile matching the target press condition
An ICC-profiled inkjet proof on approved media is the industry standard contract proof because it can accurately simulate a target press condition.
Question 7: What does a slur gauge in a pressroom control strip detect?
- Ink pH deviation from target
- Mechanical slurring or doubling of dots caused by improper press mechanics (Correct answer)
- Substrate moisture content variation
- Color rendering index of the press illuminant
Correct answer: Mechanical slurring or doubling of dots caused by improper press mechanics
A slur gauge (such as a star target or checkerboard pattern) reveals slurring or doubling artifacts that indicate mechanical problems like cylinder bounce or paper slippage.
GMI Process Control and Documentation 3
Which measurement geometry is recommended by ISO 13655 for measuring printed color on coated substrates?