Hot-Washed vs Cold-Washed rPET Flakes
Hot-washed flakes are cleaner and higher-grade; cold-washed are cheaper. Here is which one your process actually needs.
Key takeaways
- IV, moisture and PVC are the three numbers on a COA that matter most to fibre and strap makers.
- Hot-washed and cold-washed flake are different grades — compare quotes like for like.
- “Crush” is unwashed flake; “flake” in a quote usually means washed — always ask.
- Sellers: tare, deductions and grading decide what a weight is really worth.
- When in doubt, ask for the COA and a sample.
Whether you are a procurement manager comparing flake quotes or a dealer selling a truckload of bottles, the same words come up again and again. Here they are, grouped by topic.
Materials
| Term | Meaning |
|---|---|
| PET (PETE) | Polyethylene terephthalate — the plastic used for water and soft-drink bottles. Marked “1” in the recycling triangle. |
| rPET | Recycled PET — PET recovered from used bottles and turned into flake, pellets or fibre. |
| Virgin PET | New PET resin (chips) made from oil-based raw materials. rPET is priced against it. |
| Post-consumer | Material that has been used by consumers and thrown away — e.g. used bottles — as opposed to factory scrap. |
| Bottle-grade / food-grade | rPET cleaned to a standard approved for food contact. Needs special decontamination — see is recycled PET food-grade? |
| PP, PE, HDPE | Other plastics found with bottles — mainly caps, rings and some labels. They float in water; PET sinks. |
| PVC | Polyvinyl chloride. Looks like PET in some bottles but damages PET melts. Marked “3”. |
Processing
| Term | Meaning |
|---|---|
| Sorting | Separating PET bottles by colour and removing other plastics and rubbish. |
| Bale | Bottles compressed into a dense block for easier transport. |
| Crush | Bottles granulated without washing — unwashed flake. See PET bottle crush rate. |
| Flake | Small pieces of PET cut from bottles — in a quote, usually washed flake. |
| Cold-wash | Washing at ambient temperature. Removes loose dirt; leaves more glue and residue. |
| Hot-wash | Washing in hot water, typically with caustic, to remove glue, labels and residues. See hot vs cold-washed. |
| Float–sink | Separation in water: PP/PE float, PET (and PVC) sink. |
| Fines | Dust and very small particles, often from blunt blades. Lost in washing; cause feeding problems. |
| Pellets / chips | Flake melted, filtered and cut into uniform granules — a further processing step. |
The full process, from bottle to flake, is in how PET recycling works.
Quality and specifications
| Term | Meaning |
|---|---|
| IV (intrinsic viscosity) | A measure of PET chain length, in dl/g. Higher, stable IV means more melt strength — important for fibre and strapping. |
| Moisture | Water content of the flake. Too much lowers IV during extrusion; flake must be dried before processing. |
| PVC ppm | PVC content in parts per million — e.g. 50 ppm means 50 mg of PVC per kg of flake. Lower is better. |
| PP/PE content | How much cap and label plastic remains in the flake. |
| Bulk density | Weight per volume of loose flake — affects feeding and transport. |
| Flake size | Typical particle size, set by the screen in the granulator. |
| Colour / colour stream | Clear, light blue, green, brown or mixed. Clear has the most uses. |
How these are tested and reported: reading an rPET COA. How to check them at your gate: the mill gate checklist.
Documents and trade terms
| Term | Meaning |
|---|---|
| COA | Certificate of Analysis — test results for a specific lot. |
| TDS | Technical Data Sheet — the typical properties of a grade (not lot-specific). |
| Lot | A batch of flake produced and tested together. |
| Retained sample | A sealed sample kept from each lot to settle any later quality question. |
| Ex-works | Price at the supplier’s gate; the buyer arranges transport. |
| Delivered | Price including delivery to the buyer’s site. |
| FOB | Free on Board — export price at the port, before sea freight and import costs. |
| HS code | Customs classification. PET flake is commonly under heading 3915 — confirm with your customs agent. |
Terms for bottle sellers
| Term | Meaning |
|---|---|
| Kanta | The scale your load is weighed on. It should read zero before weighing. |
| Weighbridge | A scale for whole trucks — loaded weight minus empty weight gives the load. |
| Tare | The weight of empty bags or containers, deducted from the gross weight. |
| Deduction (kaat) | A weight or price cut for water, dirt or other plastics — should be explained before payment. |
| Grading | Sorting a load into clear, coloured or mixed and checking its condition — decides the rate. |
| Buy-back rate | The rate a recycler pays for your bottles, per kg. |
How rates are set: PET bottle scrap rate in Pakistan.
Need a term or spec explained for your order?
Ask us — or request a sample with its COA so you can see the numbers for yourself.
Ask a Question WhatsApp usFrequently asked questions
What does IV mean in PET flakes?
IV stands for intrinsic viscosity, a measure of the length of the PET polymer chains, reported in dl/g. Higher and more consistent IV gives more melt strength, which matters for fibre spinning and strapping.
What does PVC ppm mean?
It is the amount of PVC in the flake in parts per million. For example, 50 ppm means 50 milligrams of PVC in every kilogram of flake. Lower is better, because PVC damages PET melts.
What is the difference between a COA and a TDS?
A COA (Certificate of Analysis) gives test results for one specific lot. A TDS (Technical Data Sheet) describes the typical properties of a grade in general. Buyers usually want the TDS to choose a grade and a COA with each delivery.
What is the difference between PET crush and PET flakes?
Crush is bottles granulated without washing, so labels, glue and dirt are still present. Flake usually means washed material — cold-washed or hot-washed. Always confirm which one a quote refers to.
What is tare when selling bottles?
Tare is the weight of the empty bags or containers, deducted from the gross weight so you are paid only for the bottles. Agree it before weighing.
