The humble plastic bottle is now one of the most commonly recycled objects. However, it was the cheapness and durability of the product that led to its popularity over glass bottles. Nathaniel Wyeth, a US engineer, worked on the invention for almost a decade. When he asked a colleague if plastic might be used to store carbonated beverages such as coke, he was told that they would explode. A series of early experiments proved that carbonated beverages caused the plastic to expand. plastic was too weak, but it would have been strengthened if the long strands of molecules that form plastic were made up together. Wyeth knew that nylon gets stronger when its molecules are stretched and aligned, and he developed a preformed mold. Although initial results were far from successful and it took 10,000 attempts to solve that problem, he finally replaced the nylon with polyethylene-terephthalate (PET) - an artificial substance used to make materials for packaging food, including plastic drink bottles - and the bottle was quickly taken up by the booming soft drink industry.