GMI Ink & Substrate Interaction 2

Question 1

How does increased substrate moisture content typically affect ink drying time in heatset web offset printing?

Accepted Answer

It extends drying time because moisture competes with solvent evaporation in the dryer

Answer

It accelerates drying by increasing ink solvent activity

Answer

It has no effect because heatset drying relies solely on temperature

Answer

It causes faster ink setting but slower final drying

Question 2

When printing UV-curable inks on non-porous substrates such as plastics, which property is most critical for ink adhesion?

Accepted Answer

Substrate surface energy being sufficient to promote wetting

Answer

Ink viscosity matching substrate porosity

Answer

Ink tack being lower than the substrate tensile strength

Answer

Substrate caliper being within press specification tolerances

Question 3

Dot gain on an uncoated substrate compared to a coated substrate of the same nominal stock weight is generally:

Accepted Answer

Higher, because ink spreads more in the porous uncoated surface

Answer

Lower, because uncoated paper has higher surface energy

Answer

Equal, since dot gain depends solely on press pressure

Answer

Lower, because uncoated paper absorbs ink faster, fixing it in place

Question 4

In printing, 'show-through' and 'strike-through' differ in that:

Accepted Answer

Show-through is the visibility of printing from the reverse side, while strike-through is complete ink penetration through the substrate

Answer

Show-through is caused by UV ink, while strike-through is caused by solvent ink

Answer

Show-through occurs only on coated stocks, while strike-through occurs only on uncoated stocks

Answer

Show-through is a quality standard, while strike-through is a defect classification

Question 5

Which ink sequence principle is applied in multicolor offset printing to optimize wet trapping?

Accepted Answer

Print inks in decreasing tack order so each subsequent ink has lower tack than the previous

Answer

Print the highest tack ink last to maximize adhesion to dry ink layers

Answer

Print inks in increasing tack order to progressively build adhesion

Answer

Tack order does not affect wet trapping; only ink viscosity matters

Question 6

Static electricity in substrates during printing is most problematic because it:

Accepted Answer

Causes sheets to stick together and misregister, disrupting sheet travel and feeding

Answer

Causes ink to repel from the substrate surface, reducing ink lay

Answer

Increases ink tack, making ink harder to distribute on rollers

Answer

Prevents proper ink drying by insulating the substrate surface

Question 7

Paper whiteness and paper brightness are different measurements because:

Accepted Answer

Brightness measures the spectral uniformity across the visible range, while whiteness only measures a single UV wavelength

Answer

Whiteness measures reflectance at 457nm only, while brightness includes UV fluorescence effects across the visible spectrum

Answer

They are equivalent measurements using different instrument calibration standards

Answer

Whiteness is measured with a densitometer while brightness requires a spectrophotometer