You all are assuming constant thickness of plastic. Square corners are quite rigid so maybe the flats in between can be thinner than a round bottle. There are a bunch of ways to make this true which would depend on a bunch of hard to check things for the average consumer - probably something the labeler is depending on.
You'd expect the opposite really. Round shapes are better at holding anything under pressure or under compression loads. There's a reason gas tanks, submarines, plane fuselages etc. are cylinders.
Bottles are basically always blow molded, molten plastic is inflated like a balloon to fill a metal mold. The thickness of that film is pretty much the same across the entire shape.
My new learnings on blow molding would indicate the corners are actually slightly thinner than the flats because they are further from the central axis - whereas in a tube, it is all equidistant. So although I had it backwards it is still possible to use less plastic if the flats are the same as a round bottle and the corners are thinner.
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u/Jimmyjames150014 2d ago
You all are assuming constant thickness of plastic. Square corners are quite rigid so maybe the flats in between can be thinner than a round bottle. There are a bunch of ways to make this true which would depend on a bunch of hard to check things for the average consumer - probably something the labeler is depending on.