GMI Troubleshooting & Problem Resolution 4

Question 1

A digital press operator notices that the output density drops progressively from the lead edge to the tail edge of each sheet. The most probable cause is:

Accepted Answer

Toner or ink depletion in the developer unit causing starvation toward the end of the sheet

Answer

Progressive density drop from lead to tail edge typically indicates developer starvation as toner is consumed faster than it is replenished across a long sheet.

Question 2

A print buyer complains that two versions of a brochure printed six months apart look different despite using the same files. What is the most rigorous way to diagnose the root cause?

Accepted Answer

Pull press sheets from both runs and measure with a spectrophotometer, then compare ICC profiles used each time

Answer

Spectrophotometric measurement of both press sheets combined with a review of the ICC profiles used provides objective, measurable data to identify whether the deviation is in color management, ink, or substrate.

Question 3

When a newly installed ink shows acceptable density but extremely poor trapping in wet-on-wet lithographic printing, the technician should first adjust:

Accepted Answer

Ink tack sequence so that first-down inks have higher tack than subsequent inks

Answer

In wet-on-wet offset lithography, proper ink trapping requires that each successive ink has lower tack than the previous one so it adheres to the wet ink film already on the substrate.

Question 4

A cold-set web offset press produces sheets with ink set-off on the back of the next sheet in the delivery pile. The most effective corrective action is:

Accepted Answer

Reduce ink film thickness and use anti-set-off powder or UV drying

Answer

Cold-set inks dry by absorption and oxidation; reducing film weight and applying anti-set-off powder prevents wet ink from transferring to the back of the overlying sheet in the pile.

Question 5

A designer submits artwork with overprinting set incorrectly on a white knockout object over a dark background. On press, this will result in:

Accepted Answer

The white object disappearing because white ink overprints the dark background transparently

Answer

In CMYK offset printing there is no white ink, so an object set to overprint on a dark background simply prints nothing visible, making the white shape disappear.

(GMI) Graphic Measures International Certification Practice Test

(GMI) Graphic Measures International Certification Practice Test

GMI Troubleshooting & Problem Resolution 4