A preform spec sheet is short, but three numbers carry most of the quality story: intrinsic viscosity, acetaldehyde and weight tolerance.
IV — intrinsic viscosity
IV (dl/g) reflects polymer chain length and therefore strength. Water and juice grades run ~0.76–0.80; oil, CSD and 5-gallon grades use a higher ~0.84+ for pressure and top-load. Too low and the bottle is weak; too high and it is hard to process.
AA — acetaldehyde
AA is a trace processing by-product that can taint sensitive contents. Water grades target a low AA (< ~6 ppm); a controlled drying and melt history keeps it down — critical for still water taste.
Weight tolerance
The ± gram tolerance keeps stretch ratios and wall thickness consistent bottle-to-bottle. Tight tolerance is what makes a blow line stable.
See these on every SKU and check the stretch fit in the Preform Engineering calculator.