Metal

Nothing can be concluded from the word "metal". Safety here turns on two unknowns at once: which metal, and what is on its surface. In practice unspecified consumer metal is almost always one of four things - a stainless of unstated grade, aluminum in bare, anodized or coated form, a plated carbon steel, or a zinc die casting - and those four have genuinely different answers, which is why each has its own page. Vagueness reliably hides two specific things. One is a plating or coating over a cheaper base metal, so that the surface and the core are different materials with different lifespans. The other, in anything a drink or drinking water passes through, is brass, and therefore lead. Neither is disclosed by the word "metal", so we record these parts as unverified rather than assuming food-grade stainless. For reference, the FDA Food Code requires food-contact materials to be safe, durable, corrosion-resistant, nonabsorbent, smooth and cleanable, and to impart no colors, odors or tastes - a bar that a named alloy can be checked against and an unnamed one cannot.

Unknowable by definition, and that is the point on a site where heat is the central concern. The candidate metals are not interchangeable here: a zinc die casting softens below 400C while a stainless part is unbothered at three times that, so "metal" tells you nothing about whether a part belongs in a hot path.

Ask the brand four questions, in this order: which metal and which grade or alloy designation; whether there is any plating, anodizing or coating on the part and what it is; whether the part is solid or plated, since a plated part is a different material at the surface than in the core; and, for anything wetted by drinking water, whether any brass or bronze is in that path and whether the product is certified to NSF/ANSI 372 and NSF/ANSI 61. Three physical checks narrow it fast in the meantime. A magnet sticks to carbon and plated steel and to 400-series stainless, and does not stick to 304 or 316 stainless, aluminum, brass, copper, zinc, or titanium. Weight sorts the rest: aluminum and titanium are conspicuously light, brass and zinc conspicuously heavy. Color settles the alloys - yellow is brass, reddish is copper, and dull grey-white showing through chipped plating is usually zinc. Two answers that are not answers: "food-grade" names no defined grade, and "BPA-free" describes a plastic monomer and says nothing whatever about a metal part.

Metal is the most genuinely recycled material stream there is, but a small unidentified part inside a product is rarely separable from it, so it goes wherever the product goes.