From New Mind.

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An exploration of the evolution of the paper bag, from a simple 19th-century invention to a marvel of high-speed mass production. We explore how a series of key innovations created the modern grocery bag and what the future holds for sustainable packaging.

THE BIRTH OF MASS PRODUCTION
• Francis Wolle patented the first mass-production machine in 1852.
• It produced 1,800 "envelope-style" (V-bottom) bags per hour.
• These bags couldn’t stand upright, making them impractical.

THE BAG THAT STANDS
• Inventor Margaret E. Knight created the solution.
• Her 1871 patent automated folding for a flat, square bottom.
• This innovation let bags stand upright, making them practical for packing.

THE MODERN S.O.S. DESIGN
• Charles Stilwell patented the "Self-Opening Sack" (S.O.S.) in 1883.
• He added pleated sides (gussets) so bags could fold flat for shipping.
• The design pops open easily; Walter Deubener added handles in 1912.

KRAFT PAPER
• Complex folds required stronger "Kraft" paper (invented in the 1880s).
• "Kraft" (German: "strength") is a chemical process using "white liquor" to dissolve lignin.
• This frees long, strong cellulose fibers, creating durable "brown stock" paper.

HIGH-SPEED PRODUCTION
• Massive paper rolls are fed at high speed into a machine.
• The paper is printed, folded into a continuous tube, and sealed.
• Cutters and rollers instantly separate the tube and fold the square bottom.

STRENGTH & SAFETY
• Strength is measured by "Basis Weight" (standard grocery bags are 50-60#).
• Regulated industrial bags must be multi-wall, sift-proof, and hold up to 50 kg.
• Food-grade bags are strictest, requiring virgin pulp, safe inks, and starch glues.

THE GREEN DEBATE & THE FUTURE
• Paper manufacturing uses more water and energy than plastic.
• Its key environmental benefit is post-use: it biodegrades quickly and has a high (85%+) recycling rate.
• The future lies in eco-friendly barrier coatings (like biowaxes and PHA) to replace plastic linings.

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