PET Bottle Recycling Explained: From Bottle to rPET Flake

Key takeaways

Most PET recycling is mechanical — cleaning and reprocessing, not chemical breakdown.
Sorting and float-sink separation are what keep contamination (PVC, PP/PE, labels) low.
Washing type (cold vs hot) sets the final cleanliness and grade of the flake.
Every step maps to a quality outcome a buyer can measure on the COA.

The PET recycling process, step by step

Here is the typical mechanical route from post-consumer bottle to finished flake, and the buyer benefit of each stage.

1. Collection & incoming inspection

Post-consumer PET bottles are collected, weighed and logged, then checked for non-PET material and heavy contamination. Buyer benefit: problems are caught before processing, protecting output quality.

2. Sorting by material & colour

Bottles are separated from other polymers and graded by colour (clear vs mixed). Caps and labels are targeted for removal. Buyer benefit: consistent colour and fewer foreign polymers.

3. Crushing / granulation

Bottles are size-reduced into flakes with an industrial granulator at a controlled particle size. Buyer benefit: uniform flake that feeds smoothly on your line.

4. Float-sink separation

Flakes pass through a water density tank. PET is denser than water and sinks; lighter PP/PE caps, labels and paper float and are skimmed off. Buyer benefit: the key step for cutting PP/PE and label contamination.

5. Washing (cold or hot)

Flakes are washed to remove dust, glue and oils. Cold washing handles surface dirt; hot caustic washing removes glue and grease for a cleaner, higher-grade flake. Buyer benefit: cleaner flake and better melt behaviour. More in hot vs cold wash.

6. Rinsing & drying

A neutralising rinse follows, then the flakes are dried to a target moisture level. Buyer benefit: lower moisture means less pre-drying for you and less IV loss in the melt.

7. Quality inspection, packing & dispatch

Flakes are tested (IV, moisture, PVC, contamination), given a batch ID, packed and dispatched with a Certificate of Analysis. Buyer benefit: documented, traceable quality per lot. See how to read an rPET COA.

Mechanical vs chemical recycling — what's the difference?

The process above is mechanical recycling: PET is cleaned and physically reprocessed into flake without breaking its chemical structure. Chemical recycling depolymerises PET back to its building blocks (monomers) and rebuilds virgin-like resin — a separate, more energy-intensive and less common route, mainly used for food-grade resin production.

Frequently asked questions

How are PET bottles recycled into flakes?

Bottles are collected and inspected, sorted by polymer and colour, crushed into flakes, separated from caps and labels in a float-sink tank, washed and rinsed, dried to a target moisture, then tested, packed and dispatched as rPET flakes.

What is float-sink separation in PET recycling?

It uses a water tank: PET flakes are denser than water and sink, while lighter PP/PE caps, labels and paper float and are removed. It's a key step for reducing PP/PE and label contamination.

Is recycling PET bottles mechanical or chemical?

Most PET bottle recycling is mechanical — the plastic is cleaned and physically reprocessed into flakes. Chemical recycling depolymerises PET back to monomers and is a separate, less common route.