Mass and Thickness
Gsm is grams per square metre and describes mass per area. Caliper or gauge in millimetres describes thickness. Materials with similar grammage can have different density and stiffness. For a rigid cover, record board grade and caliper as well as wrap and lining. For a PP folder, specify sheet gauge, surface and opacity.
Material Layers
A sewn sleeve may combine an outer, cushioning and lining. A turned-edge case includes board, wrap, adhesive system and lining. Describe the functional role and specification of each layer rather than giving a single overall thickness. Assess compatibility with printing, folds, welding or sewing on the intended construction. The finished sample is the reference for how those layers interact.
Material Evidence
For recycled or certified material requests, identify the exact component and supporting evidence required. A claim on one layer should not be extended to the complete article without review. Record approved alternatives and require review of substitutions that affect fit, colour or processing. Matching a nominal measurement does not guarantee that a different grade will behave identically.
Project Checklist
- Paper: grade, gsm and writing/printing requirements
- Board: grade, caliper and layer build-up
- Plastic: polymer, gauge, opacity and surface
- Textile: composition, construction and relevant weight
- Claims: component scope and supporting evidence