PUR not curing / soft spine days later
Medium severitySymptoms
Spine still soft or smelly after 48 h
Probable causes
- Insufficient ambient humidity (PUR cures with moisture)
- film too thick
- expired or badly stored PUR
The Print Guy · 2026-10-05
Other problems in this category
Binding (hotmelt/PUR) · TPG-232
Glue squeeze-out
Glue visible at the cover joint or between pages
Binding (hotmelt/PUR) · TPG-234
Spine waving
Wavy spine or book that won't close flat
Binding (hotmelt/PUR) · TPG-229
Pages pulling out (low pull test)
Loose pages when opening the book; pull test < 6 N/cm
Binding (hotmelt/PUR) · TPG-230
Spine cracking open (cold crack)
Spine snaps and pages release, especially in cold conditions
Binding (hotmelt/PUR) · TPG-231
Glue not wetting the spine (voids)
Spine zones without glue; locally loose pages
Binding (hotmelt/PUR) · TPG-235
Cover detaching from the block
Cover separating from the spine or side guards