Preventing Score Cracking in Folding Cartons
Score cracking—visible fiber breakage along a fold—can ruin a carton’s appearance, weaken its structure, and cause failures on automated lines. Understanding the causes and engineering solutions is critical for producing folding cartons that maintain both strength and visual quality.
What Causes Score Cracking
Score cracking occurs when fibers along the fold line break instead of bending cleanly.
- Low Moisture Content: Dry board becomes brittle and less pliable (ASTM D685-22).
- Improper Score Depth: Shallow scores increase folding resistance; deep scores can cut fibers.
- Incorrect Grain Direction: Folding parallel to the grain increases cracking risk.
- Surface Coating Rigidity: Gloss varnish, films, and metallic layers reduce fiber flexibility.
Material Selection
- SBS (Solid Bleached Sulfate): Generally folds cleanly but can crack with heavy coatings or low EMC.
- CUK (Coated Unbleached Kraft): Higher tear resistance; better for humid conditions.
- FBB (Folding Boxboard): Softer surface layers reduce cracking risk in coated applications.
Tip: Match fiber composition and surface finish to the intended folding radius and production environment.
Moisture and Conditioning
- Pre-Production Conditioning: Allow board to reach equilibrium moisture content (TAPPI T402).
- Humidity Control: Maintain 40–60% RH in converting and packing areas.
- Target EMC: Typically 5–8% for most paperboard grades.
Coating and Lamination Adjustments
- Scoring After Coating: Where possible, score post-coating to reduce fiber breakage.
- Film Selection: Thinner, more flexible films reduce cracking risk.
- Relief Scoring: Adding micro-perfs in the coating layer only can relieve stress without affecting the substrate.
Testing and Quality Control
- Bend Tests: Assess crack formation on sample folds before full production.
- High-Speed Trials: Score cracking can be magnified at higher folding speeds.
- Visual Standards: Establish acceptable limits for cosmetic cracking based on brand requirements.
References
ASTM International. (2022). ASTM D685-22: Standard practice for conditioning paper and paper products for testing. ASTM International. https://doi.org/10.1520/D0685-22
Soroka, W. (2014). Fundamentals of packaging technology (5th ed.). Institute of Packaging Professionals. ISBN: 978-1-930268-37-2
TAPPI. (2019). T 402: Standard conditioning and testing atmospheres for paper, board, pulp handsheets, and related products. TAPPI Press.
Twede, D., & Goddard, R. (2021). Cartons, crates and corrugated board: Handbook of paper and wood packaging technology (2nd ed.). DEStech Publications. ISBN: 978-1-60595-120-5
The packaging industry has spent decades chasing “more.” More layers, more coatings, more colors — all to create perceived value. But in 2026, the smartest brands are realizing that doing
Packaging decisions should never be based on design alone. Without proper testing, even well-engineered boxes can fail under real-world conditions—leading to product damage, returns, and wasted costs. By testing packaging
The Regular Slotted Container (RSC) is the most widely used corrugated box style, valued for its efficiency and versatility. However, it isn’t always the right choice. Certain products, supply chain
Full Overlap (FOL) corrugated boxes are valued for their durability, with overlapping flaps that add protection on the top and bottom panels. But the strength of an FOL container depends
By submitting your information, you agree to our terms and conditions and privacy policy.
Folding cartons are a staple in the packaging industry, known for their versatility and functionality. Among the various styles available, two popular choices are the
Packaging plays a crucial role in safeguarding products from various hazards that can compromise their quality, safety, and integrity. From the manufacturing floor to the
Shipping products safely and securely is a top priority for any business. During transit, packages are susceptible to various risks, including jostling, drops, and other