B2B Paper & Board Technical Guide
A comprehensive reference dictionary on paper physics, grain direction, caliper calculations, Cobb sizing standards, and test methods for printers, publishers, and packaging converters.
GSM (Grams per Square Meter / Substance)
The standard metric measurement of paper weight representing the mass in grams of one square meter of paper (g/m²). It determines the thickness, heft, and opacity of sheets and reels across all grades.
Caliper & Bulk Density (Microns / cm³/g)
Caliper measures single-sheet thickness in thousandths of a millimeter (microns or µm). Bulk volume (Caliper / GSM) indicates how "puffy" or dense the sheet is. High-bulk paper (e.g. 1.8 to 2.0 Vol) gives thick, lightweight books with substantial paper savings.
Grain Direction (Long Grain vs. Short Grain)
The alignment direction of cellulose fibers as they travel along the paper machine wire. Long grain (LG) fibers run parallel to the longer sheet dimension; short grain (SG) runs parallel to the shorter side. Correct grain alignment parallel to the book spine is crucial for clean page turning and jam-free folding.
Cobb Sizing Value (Water Absorption Test)
Measures the amount of liquid water absorbed by the paper surface over a specific time (typically Cobb 60 seconds, expressed as g/m²). Proper Cobb balance prevents ink bleeding on offset presses and guarantees adhesive bonding on packaging cartons.
ISO Brightness vs. CIE Whiteness
ISO Brightness measures reflectance of blue light at 457 nm wavelength under standardized laboratory illumination. CIE Whiteness measures overall visual whiteness including optical brightening agents (OBAs). Premium office copier papers achieve 104%+ ISO brightness.
TEA (Tensile Energy Absorption) & Burst Factor
Critical mechanical strength metrics for industrial packaging kraft and sack papers. High TEA ensures multiwall cement and chemical sacks can absorb drop impact energy without tearing or bursting.
Standard Sheet & Ream Formats in Pakistan
| Standard Trade Size (Inches) | Metric Dimensions (mm) | Primary Applications | Available Grades |
|---|---|---|---|
| 23 x 36 in | 584 x 914 mm | Urdu text books, Quranic literature, exercise books | Woodfree Offset, Art Paper, Art Card |
| 25 x 36 in | 635 x 914 mm | English textbooks, commercial stationery, notebooks | Woodfree Offset, Art Paper, Duplex Board |
| 30 x 40 in | 762 x 1016 mm | FMCG packaging cartons, pharmaceutical boxes | Coated Duplex Board, FBB, Bleached Board |
| 31 x 43 in | 787 x 1092 mm | Master cartons, confectionery boxes, large posters | Duplex Board Grey Back, Triplex Board |
| A4 (8.27 x 11.69 in) | 210 x 297 mm | Corporate photocopying, laser printing, tenders | Prime Copier (70, 75, 80 GSM) |
B2B Paper Substance & Tonnage Estimator
International mill standard formula for sheets, reams & multi-ton press orders.
Total Sheet Area: 267.1 m² • Standard Reams: 1.0 Reams