PP, PE, PC, Tritan and PET: temperature, dishwasher and microwave at a glance
Every retail buyer eventually asks whether the bottle can go in the dishwasher. The answer depends on the resin, on the wall thickness and on which rack. Here is the chart we work from.
The chart
| Material | Continuous use | Dishwasher | Microwave | Freezer | Clarity |
|---|---|---|---|---|---|
| PP — polypropylene | up to ≈ 100–110 °C | Yes, top rack | Yes | Yes | Translucent |
| HDPE / LDPE | ≈ 80–100 °C | Top rack only, thin parts distort | Not recommended | Yes | Opaque |
| PC — polycarbonate | up to ≈ 115–130 °C | Yes | Yes, but see note | Yes | Glass-clear |
| Tritan — copolyester | up to ≈ 95–100 °C | Yes, top rack | Not for heating | Yes | Glass-clear |
| PET | ≈ 60–70 °C | No | No | Yes | Clear |
Two columns deserve a warning label. 'Continuous use' is not the melting point — it is the temperature at which the part keeps its shape under its own load over time. And 'dishwasher' means the top rack: the heating element sits under the bottom rack, and the air directly above it runs far hotter than the wash cycle temperature on the machine's dial.
What actually goes wrong, and it is rarely melting
Nothing in this category melts in a dishwasher. What happens is distortion: an oval mouth that no longer seals against its lid, a base that rocks, a screw thread that binds. It shows up after fifteen or twenty cycles, which is long after the goods have been accepted.
Thin walls distort first. A 0.8 mm PP cup and a 1.6 mm PP bottle behave differently in the same machine, which is why the honest answer to 'is PP dishwasher safe' is 'this part is, at this wall thickness, on the top rack'.
The second failure mode is crazing — a network of fine cracks in clear materials, triggered by detergent chemistry rather than heat. PC and Tritan both resist it well; PET does not, which is one reason PET belongs in single-use bottles rather than reusable ones.
PP is the workhorse
PP tolerates boiling water, survives the dishwasher and the microwave, resists most cleaning chemicals and is the cheapest of the five to mould. For shaker bottles, school bottles, lunch boxes and bathroom cups it is usually the right answer.
What it cannot do is look like glass. PP is translucent at best, and on a retail shelf next to a clear bottle that difference is visible from two metres away.
PE is softer than buyers expect
Polyethylene is flexible and forgiving, which makes it good for squeeze bottles, soft lids and gaskets. It is also the lowest-temperature material in regular drinkware use, and thin PE parts will deform in a hot dishwasher cycle even when the resin datasheet suggests otherwise.
In practice we use PE for components rather than for whole bottles: the flip-top hinge, the straw, the seal.
PC is the heat champion with a compliance question
Polycarbonate has the highest service temperature here and genuine optical clarity with high impact strength. If the requirement is a clear bottle that survives a drop onto concrete and repeated hot washing, PC does it.
Conventional PC is produced using bisphenol A. European buyers will ask about this directly, some retail programmes exclude PC outright, and a small number of markets restrict it in children's articles. The microwave note in the chart is about the same issue: heating food in PC is where the migration question becomes pointed. If your market is sensitive, either hold a BPA-free grade with the test report, or move to Tritan.
Tritan is what most Western brands now specify
Tritan is a copolyester developed to give PC-like clarity and toughness without bisphenol A. It washes well, it does not craze, and 'BPA-free' is a claim you can make in writing rather than one you have to qualify.
It costs more than PC per kilogram and it is less tolerant of sustained heat — it is a cold and ambient-drink material, not a material for pouring boiling water into. For gym bottles, shakers and premium sport bottles going to the US and EU, it is the default and has been for several years.
How to write this into a specification
- Name the resin and the grade, not the family. 'PP' is a family; the grade determines the actual heat behaviour.
- State the intended use: hot beverage, cold beverage only, or food contact with reheating.
- State the wash requirement as a test, not an adjective — for example, 'no visible distortion and no leak after 50 dishwasher cycles, top rack'.
- Require the resin batch certificate for the production lot, and retain a sealed sample from the shipment.
Which of the three main options fits a given product — and where each one fails commercially rather than technically — is covered in our comparison of Tritan, PC and PP.