Choosing the right paperboard is a balance between stiffness, print surface, sustainability, and cost. There are four primary acronyms every packaging engineer needs to know.
1. SBS (Solid Bleached Sulfate)
- Also known as: SBB (Solid Bleached Board).
- Composition: 100% virgin bleached chemical pulp. White all the way through (cross-section).
- Appearance: Bright white, ultra-smooth clay coated surface.
- Properties: Cleanest look, excellent die-cutting, no smell/taint, high stiffness per caliper.
- Best For: Cosmetics, pharmaceuticals, luxury goods, foods requiring direct contact reliability. (Paperboard Packaging Council)
- Price: $$$$ (Premium).
2. CUK (Coated Unbleached Kraft)
- Also known as: SUS (Solid Unbleached Sulfate), SUB (Solid Unbleached Board).
- Composition: Virgin unbleached chemical pulp (mostly softwood). Brown on the inside/back.
- Appearance: Clay coated white on top, brown kraft on back (or sometimes white-back).
- Properties: The strongest board in the industry. Highest tear resistance and wet strength.
- Best For: Beverage carriers (6-packs), heavy duty frozen food, laundry detergent boxes. (Paperboard Packaging Council)
- Price: $$$ (High performance).
3. CRB (Coated Recycled Board)
- Also known as: WLC (White Lined Chipboard), CCNB (Clay Coated News Back).
- Composition: Layers of recycled fiber. Top layer is white (often virgin or high-grade white waste); filler middles are grey/mixed; back is grey or brown.
- Appearance: Grey cross-section. Surface is coated white but often has slight texture/imperfections compared to SBS.
- Properties: Less stiff than virgin boards (shorter fibers). Can crack on folds if not scored perfectly.
- Best For: Cereal boxes, tissue boxes, dry food, general retail. The workhorse of FMCG. (Paperboard Packaging Council)
- Price: $$ (Standard).
4. URB (Uncoated Recycled Board)
- Also known as: Chipboard, Greyboard.
- Composition: 100% recycled newsprint/mixed paper.
- Appearance: Grey or brown. Rough finish.
- Properties: Low stiffness, high absorption.
- Best For: Set-up boxes (rigid boxes wrapped in paper), shoeboxes, partitions, layer pads. Not usually printed directly for retail.
- Price: $ (Economy).
5. Specification Basics: Caliper vs. Basis Weight
- Caliper: The thickness. Measured in “points” (1 pt = 0.001 inch).
- Example: “18 pt SBS” = 0.018 inches thick.
- Typical Range: 10 pt (light) to 28 pt (heavy).
- Basis Weight: The density. Measured in lbs/1000 sq ft (or gsm).
- Engineering Note: A low-density board (high yield) gives you the same thickness (stiffness) with less weight inside. This is desirable. Buying “by the ton” means you want more sheets per ton.
A) Glossary (short)
- SBS (Solid Bleached Sulfate): premium virgin fiberboard, white throughout. (Paperboard Packaging Council)
- CUK (Coated Unbleached Kraft): virgin unbleached board, very strong, brown back/inside. (Paperboard Packaging Council)
- CRB (Coated Recycled Board): recycled board with grey news-back or kraft-back and white clay coating. (Paperboard Packaging Council)
- Caliper: thickness of board measured in points (thousandths of an inch). (Paperboard Packaging Council)
- Basis Weight: weight of board per unit area (lbs/MSF or gsm). (Paperboard Packaging Council)
- Yield: area of board per unit weight; higher yield means “more boxes per ton.”
Citations included from Paperboard Packaging Council as noted in text.