Blog
Set-off
Set-off
/ˈsɛt ɒf/
General Definition
Set-off is a print quality defect that occurs when the printed ink, before being completely dry, transfers from the surface of one printed sheet to the back side of the subsequent sheet in the delivery pile. This transfer results in an undesirable shadow effect or smearing on the back of the following sheet. The issue is mainly caused by a combination of factors including high press speed, unsuitable environmental conditions, and most importantly, high TIC, which significantly extends the ink's Drying Time.

Set-off occurs when wet ink transfers from material A to the back of material B.

Set-off occurs when wet ink transfers from material A to the back of material B.
Real-World Usage
Set-off is usually evident in areas of the design with very high ink density, such as deep shadows or large areas of solid color coverage. Excessive TIC not only prolongs the drying time, but the mechanical pressure of the delivery pile (the weight of all stacked sheets) compresses the semi-dry ink, facilitating its transfer to the back of the sheet above it. To combat this phenomenon, print shops employ various techniques. One of the most common methods is the use of Anti-Set-off Powder, which is sprayed onto the printed sheet to create a minute air gap between sheets, minimizing direct contact between the ink and the back of the subsequent sheet.
However, the qualitative and preventive solution is precise Color Separation management and TIC reduction during the Prepress stage. Using methods like GCR instead of UCR can reduce the total ink amount by replacing colored inks with Black, drastically lowering the probability of Set-off. Additionally, fine-tuning the ink's drying time relative to the paper type and using accelerating additives in the ink are crucial steps the press operator must consider to prevent this problem.
Consultant's Note
As a production consultant, it is suggested that, you recognize the Set-off problem not just as a press issue, but as a failure in Prepress management. Before sending the file to press, your team should check the TIC report and ensure that the maximum ink coverage does not exceed the safe threshold defined in the ICC Profile (e.g., 300% to 330%). This preemptive action reduces the reliance on temporary solutions like anti-set-off powder, which itself can negatively affect the quality of finishing and the final appearance of the job.
To eliminate Set-off at the root, establish a strong communication bridge between the Prepress and press sections. The press operator should immediately reduce ink density or adjust press speed upon seeing the first signs, while the Prepress team must set their standard based on safe TIC. By reducing TIC and utilizing GCR, process stability is guaranteed, and the final product quality will be maintained without unwanted smearing or shadows.
FOGRA / Idealliance / Kodak
Related Tags



