Water absorption of commercial and laboratory tissue sheets

Commercial kitchen towels (basis weight 39 to 56 g/m²) made of virgin and recycled fiber, produced by Through-Air-Drying (TAD), and conventional Yankee cylinder drying (with creping) were analyzed. The properties of these commercial tissue products were compared to those of handsheets made from them. Laboratory tissue handsheets were also prepared from northern bleached softwood kraft (NBSK), eucalyptus, bamboo, and straw pulp. Fibers were refined with up to 5000 revolutions of a PFI mill. Commercial kitchen towels (kitchen tissue) absorbed 9 to 14 g water per 1 g of fiber, with higher absorption by virgin fibers, and when using TAD. The tensile index (dry) was 3 to 14 Nm/g. Laboratory tissue handsheets made of commercial samples absorbed less water, but the tensile index (dry) was higher in most cases. Higher beating levels (tested at NBSK, eucalyptus, bamboo, straw pulp) increased tensile index. Curl, bulk, softness, absorption capacity, and suction lift were reduced with refining. Best values for absorption capacity (almost 8 g/g), bulk (almost 5 cm³/g), and softness were observed in laboratory bamboo tissue sheets made of non-refined fibers. After refining (2000 revolutions), the tensile index of such tissue sheets made of bamboo increased from 10 to 30 Nm/g.