Blocking of sheets, rolls, or cartons

Blocking is the pile or the roll sticking to itself. Soft ink, a warm stack, residual solvent, or a coating that stayed tacky are the usual causes.

Checks

1. Separate a blocked stack slowly. Ink that pulls away is still soft. A coating that feels tacky was not fully cured.
2. Cool and vent the pile. Heat held in a tight stack keeps oxidative and solvent systems open.
3. Check rewind tension and storage temperature on rolls. A warm roll blocks even when the web felt dry on press.
4. If a laminate or varnish was applied over wet ink, fix the dry step before you add more barrier.

Materials in the directory

Compare coatings, laminating films, coated paper.