What is a petaloid base?

A PET bottle base with five (or more) feet, used on carbonated drinks; the feet spread the CO₂ pressure load so the base stays flat instead of bulging or rolling out.

Why do CSD bottles have a petaloid base?

Carbonation pushes the base outward; the petaloid feet resist that pressure and keep the bottle standing flat, where a simple flat base would bulge.

What base does a hot-fill bottle use?

A hot-fill base is built to take the vacuum and thermal stress of filling hot juice or tea, usually paired with vacuum panels in the body; it is stiffer than a cold-fill base.

What base does a still-water bottle use?

A simple flat or slightly domed base — still water is not pressurised, so it does not need petaloid feet, which keeps the bottle lighter and cheaper.

Does the bottle base affect the preform?

Yes — a pressurised petaloid or hot-fill base needs more material and a higher-IV resin in the base region, which the preform weight and design must provide.

PET Bottle Base Types: Petaloid, Hot-Fill and Standard

The base is the hardest-working part of a PET bottle — it carries the pressure of a carbonated drink, the vacuum of a hot-fill, or simply the weight of stacking. Its shape is chosen for the product, not for looks. Here are the main PET base types and when each is used.

Why the base matters

For pressurised and hot-filled products the base is the highest-stress zone. Get it wrong and the bottle bulges, rocks, rolls out or stress-cracks. The base design and the preform that feeds it must match the fill.

Petaloid base — carbonated drinks

A petaloid base has five (or more) feet, like petals. The feet spread the internal CO₂ pressure so the base stays flat instead of bulging outward. It is the standard for CSD on a PCO 1881 neck, and it needs enough material and a higher-IV resin in the base — see blow-molding a CSD bottle.

Standard flat base — still water

Still water is not pressurised, so it uses a simple flat or slightly domed base — lighter and cheaper, with no petaloid feet to form. This is why a water preform can run so light.

Hot-fill base — juice and tea

Hot-filling creates a vacuum as the hot product cools. A hot-fill base is stiffer and works with vacuum panels in the body to absorb that vacuum without deforming — see hot-fill vs cold-fill.

Champagne / base-cup (legacy)

Older CSD bottles used a deep champagne push-up, or a hemispherical bottle with a separate glued-on base cup. Both are largely replaced by the one-piece petaloid base, which is lighter and faster to run.

How the base ties to the preform

A pressurised or hot-fill base needs more material exactly where the preform delivers it — so base type drives preform gram weight and design (see preform weight guide). Delta El Nile for Industry matches the preform to your base and fill — build an RFQ.