From Natural Rubber to Recyclate: Which Plastics School Supplies Are Made of Today

As the new school year begins, millions of pencil cases, school bags and pens end up in children's hands. Many of these school supplies are made from carefully chosen plastics or rubber. Key criteria for material selection include properties such as transparency, shatter resistance and abrasion resistance. Increasingly, recyclates and bioplastics are being used as well.

School supplies show how important it is to focus on functionality when choosing materials:

• Rulers and set squares are usually made of polystyrene (PS) or the higher-grade PMMA (acrylic glass) – both crystal-clear, rigid and dimensionally stable, so that the scale and edges stay precise.
• Ballpoint pens and fountain pens often use ABS, polypropylene (PP) or PS: impact-resistant, easy to colour and comfortable to hold.
• Erasers come as rubber erasers (made of natural or synthetic rubber) and as plastic erasers (made of plasticised PVC or PVC-free thermoplastic elastomers). Whichever version is used, what matters is how well the material abrades and picks up the graphite in the process.
• School bags, backpacks and pencil cases can be made of polyester fabric (PET). This makes them particularly tear-resistant, lightweight and weatherproof; increasingly, these items are also made from recycled PET (rPET).
• Lunch boxes and drinking bottles rely on PP or Tritan (a copolyester): food-safe, shatterproof and dishwasher-safe.

Many school supplies look back on a longer material history. The eraser, for instance, came about by chance: until the 18th century, pencil marks were rubbed out with kneaded balls of breadcrumbs. In 1770, the British instrument maker Edward Nairne accidentally reached for a piece of rubber instead of a ball of bread – and discovered its erasing power. It was only through vulcanisation, discovered by Charles Goodyear in 1839, that sticky natural rubber became a durable elastomer.

Writing instruments tell a material story too: early fountain pens were made from ebonite, a hard rubber, and celluloid – the latter, developed around 1868 by John Wesley Hyatt, is regarded as one of the first thermoplastic materials and replaced ivory. In the early 20th century, Leo Hendrik Baekeland patented Bakelite, the first fully synthetic plastic, from which housings, switches and pen components were later made.