Every product we review starts with the same grind: a listing that says “stainless steel,” a gallery of flattering photos, and a gasket somewhere that nobody mentions. This article is our checking process, written up so you can run it yourself on anything we haven’t covered yet.

The core rule: a product is a bag of parts, and claims are made about the flattering parts. “Glass kettle” describes the carafe, not the lid, the fill line, or the tube you can’t see. Vet parts, not products.

Step 1: know where plastic hides

After a few hundred teardowns, the hiding spots are extremely predictable. Check these before anything else:

  • Lids and their undersides. The #1 offender. A “stainless” container with a plastic lid is the industry default. And a metal lid usually has a plastic or silicone gasket under its rim.
  • Valves, spouts, and straws. Anything that clicks, flips, seals, or regulates flow is almost always plastic — sippy cups and travel mugs live and die here.
  • Internal water paths in anything electric. Kettles, coffee makers, rice cookers: the visible body can be steel while the water tube, level gauge, or reservoir is plastic. If water moves through a machine, assume a hidden plastic segment until proven otherwise. Bonus check: is the plastic in the hot path?
  • Coatings. Nonstick (see the PTFE explainer), “ceramic-coated” aluminum, painted exteriors that reach the rim, and the epoxy lining inside most metal cans and some bottles.
  • Fittings on wood and bamboo. Glued joints, rubber feet, and — on “bamboo” dishware specifically — melamine resin binder, which is plastic even though the product is marketed as plants.

Step 2: decode the listing language

Copywriters choose words that are technically true. Translations:

  • “Plastic-free” — often means the packaging, or “no plastic you can see.” No regulator checks this word.
  • “BPA-free” — the item contains plastic, and the brand hopes that’s reassuring. (It shouldn’t be — myth #1.)
  • “Stainless steel body” — the qualifier “body” is doing heavy lifting. What’s the lid, seal, spout, and interior?
  • “Glass” in the product title — describes the main vessel only, by convention.
  • “Food-grade silicone” — fine as far as it goes, but note which part, and whether it’s a cold seal or in a hot/primary food path — that distinction is most of the silicone question.
  • Material simply not mentioned for a specific part — treat silence as “plastic.” Brands that use steel and glass say so, loudly, per part.

Step 3: read the photos like a teardown

  • Zoom every gallery image; look for mold parting lines and injection marks (fine seams, a small circular dimple) — signatures of molded plastic.
  • Renders vs. photographs: uniform, grainless, reflection-perfect images are CAD renders and prove nothing about materials.
  • Find the exploded or parts view in the manual (often downloadable pre-purchase) — service manuals name materials that listings hide.
  • Check the replacement parts page: if the brand sells “gasket (silicone)” or “lid assembly (Tritan),” you have your answer without asking anyone.

Step 4: ask the manufacturer — specifically

Support teams answer the question you ask, so never ask “is it plastic-free?” (You’ll get “it’s BPA-free!”) Ask per-part, yes/no:

What material is the lid gasket? What material is the internal tube between the reservoir and the spout? Does water or steam touch any plastic or silicone part at any point between filling and pouring? If so, which parts?

Three useful properties of this framing: it can’t be answered with a slogan, “I’ll have to check” tells you the front-line answer would have been a guess, and a written reply gives you (and us) a citable source. When you get one, that’s exactly what our manufacturer-confirmed verification level means.

Step 5: check the communities

Reddit and enthusiast forums are where gaskets get named. Search the product plus “plastic,” “gasket,” “tube,” or “teardown” — r/BuyItForLife, r/PlasticFreeLiving, and product-specific subs regularly settle in one thread what listings obscure. Weigh it appropriately: this is our community-reported tier — genuinely useful, occasionally wrong, best when someone posts photos of the disassembled part.

Red flags worth walking away from

  • A “plastic-free” claim on a product with an unphotographed lid interior.
  • No materials section anywhere — brands proud of steel and glass itemize.
  • “Proprietary blend” or “eco-material” without a chemistry name.
  • Reviews mentioning a smell, cloudy water, or a cracked part that the listing calls metal.

Or let us do it

This checklist is literally the site: every product page is steps 1–5 run to completion, with a component-by-component table, each claim’s source, and an honest verification level — down to unverified when a claim is our best reading of photos and we couldn’t do better. If we’ve covered the product, the work is done; if we haven’t, this is the manual. (And if you run the process on something we’re missing — send it in.)