08/10/2026
On a sheetfed press, the sheet is not held by suction alone. A row of metal fingers, the grippers, clamps one edge of every sheet and carries it through the units, from the feeder to the delivery. The strip of sheet those fingers need is the gripper margin, and it has to be left blank.
๐๐จ๐ฐ ๐ญ๐ก๐ ๐ฌ๐ก๐๐๐ญ ๐ข๐ฌ ๐ก๐๐ฅ๐
The grippers close on a bare strip, usually around ten to twelve millimetres deep along the leading edge. Nothing can be printed there, because the fingers would smear wet ink and the clamp would crush the image. When the sheet reaches the delivery, the same strip is often trimmed away or folded into the spine, so the unprinted edge never shows.
๐๐ก๐๐ซ๐ ๐ญ๐ก๐ ๐ฆ๐๐ซ๐ ๐ข๐ง ๐ ๐จ๐๐ฌ ๐ข๐ง ๐ญ๐ก๐ ๐ฅ๐๐ฒ๐จ๐ฎ๐ญ
A designer working on a flat sheet has to plan for it. The sheet has a gripper edge and a side guide edge, and both need clearance. A sheet printed in more than one pass is turned or backed up, so the gripper margin moves to the other edge on the second pass. The layout is arranged so that the bare strips fall in the trim, not in the live area.
๐๐ก๐๐ญ ๐ก๐๐ฉ๐ฉ๐๐ง๐ฌ ๐ฐ๐ก๐๐ง ๐ข๐ญ ๐ข๐ฌ ๐ข๐ ๐ง๐จ๐ซ๐๐
If artwork runs into the gripper strip, the press has two choices, and both are bad. It can print the edge and accept the marks and scuffing where the fingers held the sheet. Or it can move the image, which throws the position of everything on the sheet out of line with the trim. Either way, the fault is in the file, not on the press.
๐๐จ๐ฐ ๐ ๐ฉ๐ซ๐ข๐ง๐ญ๐๐ซ ๐ก๐๐ง๐๐ฅ๐๐ฌ ๐ข๐ญ
For work that has to fill the sheet, the press can print the gripper area and accept the waste, then trim it off. For a tight run, the layout is set so the grippers sit in a margin that was going to be cut anyway. The operator checks the grip before the run, because a light grip drops sheets and a heavy grip marks them.
๐๐ก๐ฒ ๐ข๐ญ ๐๐๐ฅ๐จ๐ง๐ ๐ฌ ๐ข๐ง ๐ญ๐ก๐ ๐๐ข๐ฅ๐ ๐๐ก๐๐๐ค
A preflight that reads the trim, the bleed and the fold should also read the gripper and side guide. Those two strips are the only parts of the sheet the press physically needs, and a layout that reserves them prints cleanly on the first pass. It is a quiet detail, and it decides whether the job runs without a second proof. As book printing continues to lead in production quality and innovation, the industry sets new benchmarks for print manufacturing worldwide.