Glossary
PET Packaging Glossary
Plain-English definitions of the PET preform, closure and bottle terms buyers and engineers use most — neck finishes, materials, quality and process. From Delta El Nile for Industry, an Egyptian PET preform & closure manufacturer since 1996.
Preforms & bottles
- PET preform
- An injection-moulded PET intermediate, shaped like a test tube, later reheated and stretch-blow-moulded into a finished bottle. Delta El Nile for Industry’s public range spans 9 g to 668.5 g.
- Stretch-blow moulding (SBM)
- The process that reheats a preform and blows it into a bottle inside a mould; strength comes from the bi-axial stretch.
- Top-load
- A bottle’s vertical compression (stacking) strength — a key driver of how light a preform can go.
Neck finishes
- Neck finish
- The standardised threaded top of a preform/bottle that mates with a specific closure. Fixed before the bottle is blown; must match the filling line and cap.
- PCO 1881
- The global standard short-neck finish for carbonated soft drinks — the lightweighted successor to PCO 1810, with a shorter thread that saves resin while withstanding carbonation pressure.
- PCO 1810
- The older, taller CSD neck finish; heavier than PCO 1881 and still specified on some legacy lines.
- 29/25
- A light, short neck finish for still water, optimised for low cost and high-speed filling.
- 32/15
- A neck finish commonly used on juice and dairy bottles.
- 29/21
- A neck finish used for edible-oil bottles, with one-piece and two-piece closures.
- 55 mm
- A wide neck used on 5-gallon (≈19 L) returnable water bottles.
Materials & recycling
- rPET
- Food-grade recycled PET resin — cuts packaging carbon and meets recycled-content mandates. Food-contact use requires certified super-clean recycling (EFSA in the EU, FDA in the US).
- IV (intrinsic viscosity)
- A measure of PET molecular weight / melt strength that drives bottle performance and is tuned when blending rPET.
- Lightweighting
- Reducing preform gram weight while preserving performance, to save resin and carbon.
Quality & process
- Stretch ratio (BSR / HSR / ASR)
- Ratios relating preform geometry to the blown bottle — hoop (HSR), axial (ASR) and overall blow-up (BSR). The workable BSR window is roughly 5.0–14.0.
- IMD inspection
- In-mould, camera-based defect inspection of preforms and closures. Delta runs 6-camera IMD on its lines.
- Acetaldehyde (AA)
- A trace by-product of PET melt processing; excess AA can taint the flavour of bottled water, so melt temperature is controlled.