Since 1963, LEGO bricks have been manufactured from acrylonitrile-butadiene-styrene copolymer - ABS copolymer for short - a plastic with a matte finish. It is very hard and robust - import criteria for a children's toy. Laboratories in Switzerland and Denmark regularly test the quality of the ABS. The plastic is distributed to factories as granules rather than in liquid form. These grains of plastic are heated up to 232ºC and converted into a molten mass. Injection moulding machines weighing up to 150 tonnes squeeze the viscous plastic mass into the desired injection moulds - of which there are 2,400 varieties. After seven seconds, the brick produced in this way has cooled down enough to be removed from the mould. The injection moulding method is so precise that out of every million elements produced, only about 18 units have to be rejected. Unsold bricks are converted back into granulates and recycled.

Christian Humberg