Deformed spine or uneven block at gluing
Medium severitySymptoms
Wavy, rhomboid or stepped spine; cover won't seat
Probable causes
- Uneven gathered block (varying signature sizes)
- insufficient jogging before the clamp
- loose clamp
The Print Guy · 2026-10-05
Other problems in this category
Gathering/Stitching/Gluing · TPG-241
Staple tearing the spine
Paper tearing at the staple; booklets loosening in use
Gathering/Stitching/Gluing · TPG-243
Crooked or variable trimming (trimmer)
Magazines with uneven margins; off-square head/foot/front cuts
Gathering/Stitching/Gluing · TPG-244
Spine hotmelt wicking between pages
Center pages stuck near the spine; book won't open flat in places
Gathering/Stitching/Gluing · TPG-237
Missing, duplicated or out-of-order signature
Books with skipped or duplicated pages; client complaints
Gathering/Stitching/Gluing · TPG-238
Double signature fed from one station
Thicker blocks; double mark in the spine staircase; stitcher jams
Gathering/Stitching/Gluing · TPG-239
Signature not opening at the center on the saddle
Signatures dropping closed or off-center onto the chain; stitching off the fold