Material Characterization
Economical multi-ply containerboards produced entirely from unsorted mixed recovered paper fibers provide functional containment for non-critical packaging applications. The testliner 3 grade represents a standard recycled linerboard category defined by baseline physical strength thresholds and basic surface performance requirements. Mills manufacture this paperboard utilizing mixed waste paper streams, resulting in a furnish composed of varied, heavily recycled wood and mechanical pulp fibers.
The top layer receives minimal fiber sorting and light surface sizing, leaving a natural brown, visually variable sheet surface. This grade delivers the lowest bursting strength and compression metrics among formal testliner classifications, serving applications where structural demands and graphic expectations remain modest.
Technical Limitations
Multiple mechanical recycling cycles degrade the average fiber length and cell wall bonding capacity of the constituent furnish. The testliner 3 grade exhibits lower short-span compression strength, reduced ring crush resistance, and higher moisture sensitivity than testliner 2 or virgin kraftliner alternatives. Surface roughness and variable porosity can lead to uneven ink absorption and dot gain during flexographic printing, restricting its use primarily to simple one-color or two-color shipping marks.
Corrugator operators must run this substrate with precise web tension controls to avoid sheet breaks caused by foreign particle inclusions or localized weak spots in the recycled web.
Commercial Role
Packaging converters select this board grade for inner liners of multi-wall corrugated board, interior partitions, void fillers, and non-stacking secondary shipping containers. The testliner 3 grade offers substantial material cost savings and low carbon footprint metrics for short-transit retail distribution channels. Because the sheet rapidly softens and loses rigidity in humid warehouse environments, structural packaging calculations require generous safety margins when this grade is used in load-bearing cases.
The grade represents a functional, circular packaging material that maximizes secondary fiber utilization across basic industrial packaging formats.
