Jelly shoes are made from various plasticized materials, the most common of which is PVC. PVC, which stands for polyvinyl chloride, has many potential formulations and can be both rigid and flexible. It's relatively cheap to make, and products made from it tend to be long lasting and low maintenance.
Making jelly shoes is a pretty straightforward process. At Grendene, for example, machinists use CNC machines (that stands for computer numerical control) to shape the molds for their various brands. The jellies are then formed through the process of injection molding; PVC resin, along with lots of additives to adjust the shoes' rigidity, texture, color and other physical characteristics, is forced into the molds to take shape. Researching which additive combinations work best is a big part of their process -- they've currently concocted more than 70 different formulations for PVC [source: Grendene]. Some even incorporate recycled PVC [source: Michault].
Lots of other products are made from PVC, too. It's used heavily for construction, automotive, agricultural, medical, electronic and packaging purposes. It can also be found in consumer goods ranging from garden hoses to sporting goods and kitchen appliances to kids toys.
On the next page, we'll examine the journey jellies have made through the do's and don'ts lists of fashion magazines over the years.