Plastic Bottle Preforms
Nelly, our current CouchSurfing hostess, works for a bottle manufacturing company here in Plovdiv. Although she doesn't think much of the job, our conversation about it revealed a really interesting piece of information on how plastic bottles are produced.
Nearly all plastic bottles start as a much smaller plastic bottle, called a preform. Since transporting a truck full of empty plastic bottles from the manufacturing plant would waste a tremendous amount of space, preforms can be thought of as something like a deflated balloon, ready to be blown up and filled at a bottling facility. The plastic preforms that Nelly deals with are typically used for wine and carbonated beverages in Bulgaria, and partially made from recycled materials.
The preforms are made out of a polymer called polyethylene terephthalate, commonly known as PET. When the preform is heated at a bottling plant, a gas is blown into the test tube of plastic, where it takes the shape of a mold.
The plastic preforms that she helps produce come with full-sized final threaded openings, and take standard plastic soda bottle tops.