Blocking after lamination: check the solvent blend before the ink

Blocking — printed surfaces sticking to each other on the reel — is one of the most common calls we get. It is also one of the most often misdiagnosed: the ink gets blamed when the drying profile or the rewinder is the real cause.

1. Retained solvent

Solvent that is still in the film when the reel is wound has nowhere to go. It softens the ink film, and under reel tension the layers weld together. Slow solvents make this worse: they are chosen to keep the plate wet, but they also leave the film last.

Try the ink at a faster blend first, and check that the drying tunnel is actually reaching the web temperature you think it is.

2. Rewind tension and cooling

Winding a warm, slightly tacky web at high tension produces blocking regardless of the ink. Check the chill roll, and reduce tension before changing formulation.

3. Ink film weight

Heavy coverage — a solid white or a large area of gold — traps more solvent per square metre. If only the heavy-coverage jobs block, the drying capacity is the constraint, not the resin.

4. Then look at the ink

If the job still blocks after the first three checks, the resin system may need a harder, faster-releasing grade. That is a formulation conversation we are happy to have — but it should come fourth, not first.

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