Five plastics used for cup lids: PP, PS, AS, SK and Tritan

On a stainless steel cup, the plastic is mostly in the lid, and almost every lid is made from one of these five. From cheapest to most expensive: PP, PS, AS, SK and Tritan.

The five plastics

PP (polypropylene). It can’t be made fully clear. It comes out milky or frosted. It handles over 100°C and can go in the microwave. It’s tough and doesn’t crack when dropped. Most lid bodies, straws and seal holders are PP.

PS (polystyrene). Very clear, but it doesn’t take much heat: it starts to soften at around 70–90°C, so it isn’t for hot drinks. It’s brittle and cracks when dropped. It’s used for low-cost clear parts. Most disposable coffee lids are PS.

AS (styrene acrylonitrile, also called SAN). Clear, harder than PS and more scratch-resistant. It takes a little more heat than PS, but it still isn’t made to hold hot water all day or go through the dishwasher, and it’s still fairly brittle. It’s used for clear slide lids on tumblers and for cold-drink cups.

SK (a copolyester from SK Chemicals, sold as ECOZEN). Almost as clear as Tritan. The higher grades take about 100°C. It’s tough. It’s usually chosen as a lower-cost alternative to Tritan.

Tritan (a copolyester from Eastman). The clearest of the five, close to glass. Eastman’s data sheet for Tritan TX1001 gives a heat deflection temperature of 99°C, and it’s dishwasher-safe. It’s also the toughest of the five. It’s used for premium clear lids, sports bottles and kids’ cups, and it’s the one buyers most often ask for by name.

About BPA

None of these five plastics contains BPA. The BPA concern comes from polycarbonate (PC), which isn’t one of them.

Which one to use

An opaque lid body: PP.

A low-cost clear part or a cold-drink cup: AS.

A clear lid for hot drinks or the dishwasher: Tritan, or SK if the budget is tighter.

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