Lego, which uses 20 different conventional plastics, has said substitutes must be as durable, perfectly interlocking and “backwards compatible” as its current Lego bricks.
Tim Brooks, vice president of environmental responsibility for the Lego Group, speaking to Quartz, highlighted the need for durability. “I’m about to pass on the Lego bricks I played with as a child and the bricks my dad passed down to me to my son,” says Brooks. “We know Lego bricks are often passed down through generations—making it so important that the sustainable materials chosen for our products be extremely durable.” He says 70 materials experts are testing potential replacements for strength, stiffness, dimensional stability, and impact strength.
The requirements vary by the form. Bricks require tough materials like acrylonitrile butadiene styrene, axels and gear wheels need low friction, small connectors have to be strong and stiff, while tires should be soft. All biobased replacements must also be capable of precise molding, he adds.
Shine is also key, with bricks made from wheat sugar looking dull and flat next to an incumbant block.