About Ink Offset (Backside Ink Transfer)

Ink offset (backside ink transfer) is a phenomenon where ink from the printed surface transfers onto the backside of the sheet stacked above it. This can occur when printed sheets are stacked before the ink has fully dried, or when pressure is applied during trimming or finishing. It is also referred to as「color transfer」.

Ink offset occurs when several factors overlap.

Even if the surface appears dry immediately after printing, the ink may not yet be fully cured internally. Offset printing requires a chemical reaction called oxidative polymerization for the ink to cure completely, which may take from half a day to several days.

If printed materials are stacked during this drying stage, ink may transfer onto the backside of adjacent sheets.

The pressure applied by the cutting blade during trimming, or by the folding mechanism during finishing, can press wet or semi-dry ink onto adjacent sheets, causing ink offset. This is especially common in designs with solid fills or large areas of dark colors, where ink coverage is high.

• Uncoated paper: The rough surface absorbs ink quickly but prolongs the time required for full drying
• Matte-coated paper: Has a low-gloss surface where ink tends to remain on top

Certain types of designs require large amounts of ink and therefore increase the risk of ink offset:

• Large solid color areas (especially black, dark navy, and other dark colors)
• Gradients
• Designs containing many photos or illustrations
• Double-sided printing where both sides have heavy ink coverage

By considering the points below during data creation, you can reduce the risk of ink offset.

Set the total CMYK ink coverage to 250% or less. The thicker the ink film, the longer it takes to dry, increasing the likelihood of ink offset.

When dark, saturated colors extend to the paper edges, pressure during trimming can easily cause ink transfer. We recommend using lighter colors near the edges or leaving some margin whenever possible.

Using fast-drying papers such as glossy coated stock can reduce the risk of ink offset.

Designs with more white space or lighter colors make ink offset less visible even if it occurs.