) and extruded through a circular die to form a continuous tube, which is then inflated with air to achieve the desired thickness (measured in "mils").

The foundational technology for reclosable bags emerged in the early 1950s:

Steven Ausnit developed the "press-to-close" zipper, which eliminated the need for a slider, significantly reducing production costs and making the bags viable for consumer use.

They are primarily made from Low-Density Polyethylene (LDPE) resin, known for its flexibility and clarity. Process: Resin pellets are melted (between