Kraft paper

Kraft paper or kraft is <a href="/facts/Paper/FUETwwKV">paper</a> or <a href="/facts/Paperboard/A1Nq26z2">paperboard</a> (cardboard) produced from <a href="/facts/Chemical_pulp/wIlq5nWm">chemical pulp</a> produced in the <a href="/facts/Kraft_process/bJAAtnlT">kraft process</a>.
Sack kraft paper (or just sack paper) is a porous kraft paper with high <a href="/facts/Elasticity_(physics)/wcJoIFg1">elasticity</a> and high tear resistance, designed for packaging products with high demands for strength and durability.
Pulp produced by the kraft process is stronger than that made by other <a href="/facts/Wood_pulp/wIlq5nWm">pulping processes</a>; acidic <a href="/facts/Sulfite_process/edJVxor2">sulfite processes</a> degrade <a href="/facts/Cellulose/wYPafTU0">cellulose</a> more, leading to weaker fibers, and mechanical pulping processes leave most of the <a href="/facts/Lignin/CdaxpB3b">lignin</a> with the fibers, whereas kraft pulping removes most of the lignin present originally in the wood. Low lignin is important to the resulting strength of the paper, as the <a href="/facts/Hydrophobic/Ifya0CXQ">hydrophobic</a> nature of lignin interferes with the formation of the <a href="/facts/Hydrogen_bonds/85V86IIg">hydrogen bonds</a> between cellulose (and <a href="/facts/Hemicellulose/s7wg6TEP">hemicellulose</a>) in the fibers.
Kraft pulp is darker than other wood pulps, but it can be <a href="/facts/Bleaching_of_wood_pulp/lWRshQJ4">bleached</a> to make very white pulp. Fully bleached kraft pulp is used to make high quality paper where strength, whiteness, and resistance to yellowing are important.

Kraft paper open-in-new

Kraft paper