CPT Printing & Decoration Technologies 3 — Questions and Answers
Question 1: Digital inkjet printing in packaging is best suited for which production scenario?
- Very high-volume runs requiring low per-unit cost
- Short runs with variable data and fast changeovers (Correct answer)
- Printing on highly absorbent corrugated substrates only
- Applications requiring gravure-quality cell resolution
Correct answer: Short runs with variable data and fast changeovers
Digital inkjet excels at short runs and variable data printing because it requires no plates and can change artwork job to job.
Question 2: In offset lithography, the image and non-image areas of the plate are separated by:
- Physical height differences
- Chemical differences exploiting oil-water repulsion (Correct answer)
- Laser ablation channels
- Electrostatic charge patterns
Correct answer: Chemical differences exploiting oil-water repulsion
Offset litho plates are chemically treated so image areas accept oil-based ink while non-image areas accept water and repel ink.
Question 3: Which substrate surface characteristic most significantly affects ink adhesion?
- Basis weight
- Surface energy (dyne level) (Correct answer)
- Caliper thickness
- Moisture content of the core
Correct answer: Surface energy (dyne level)
Surface energy, measured in dynes/cm, must be higher than the ink's surface tension for proper wetting and adhesion.
Question 4: Laser scoring and laser ablation in packaging decoration are examples of which decorating category?
- Additive printing
- Subtractive surface modification (Correct answer)
- Lamination
- In-mold labeling
Correct answer: Subtractive surface modification
Laser processes remove or alter material from the surface (subtractive), creating effects like matte windows or hinge lines without adding ink.
Question 5: The term 'misregister' in multicolor packaging printing describes:
- Ink color shift due to pH change
- Misalignment between successive color layers (Correct answer)
- Incorrect barcode placement
- Ink viscosity variation between printing stations
Correct answer: Misalignment between successive color layers
Misregister occurs when color separations do not align precisely, producing blurry edges or color fringing on the printed image.
Question 6: Expanded Color Gamut (ECG) printing uses how many fixed ink colors to reduce spot color usage?
- 4 (CMYK)
- 6 (CMYK + OG)
- 7 (CMYK + OGV) (Correct answer)
- 8 (CMYK + OGVB)
Correct answer: 7 (CMYK + OGV)
ECG typically uses 7 fixed inks — CMYK plus Orange, Green, and Violet — to simulate most spot colors without dedicated ink changes.
Question 7: Rub resistance of a printed surface is primarily improved by:
- Increasing ink film thickness
- Applying an overprint varnish or coating (Correct answer)
- Using coarser anilox line screens
- Reducing ink cure time
Correct answer: Applying an overprint varnish or coating
An overprint varnish or laminate creates a protective layer over the ink, significantly improving scuff and rub resistance.
CPT Printing & Decoration Technologies 3
Digital inkjet printing in packaging is best suited for which production scenario?