Lightweighting has been discussed for a decade as a technical exercise. With modern metrology it has become a commercial one, and the commercial case has started to close on its own.
Where the weight comes out
Not from the body — from the shoulder and neck, where the distribution control has improved most. The body carries the pressure, so the material there is doing work.
The line economics
The filling and packing lines in a plant are sized for a certain throughput. Lighter bottles change the pack density and therefore the number of cartons a line handles per hour, which is a factory-wide effect that rarely appears in a business case.
Brand considerations
Lightweight glass is perceived as premium. For a category where volume is driven by a marketing idea of quality, better economics and better brand position point the same way.
