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What's in a vape coil — heating elements, "dry hits," and metal exposure
The part of a vape device that does the actual work is small and easy to ignore — a thin coil of resistance wire wrapped around a wick, heated by the battery to vaporize e-liquid. Most vapers replace coils on a schedule without thinking much about what they're made of or why an old one starts to taste burnt. Both questions turn out to matter.
What coils are actually made from
Vape coil wire is typically a metal alloy — common choices include kanthal (an iron-chromium-aluminium alloy), nickel-chromium, or stainless steel — chosen for its resistance properties and how evenly it heats. The coil sits inside a wick, usually cotton, that draws e-liquid up to the hot wire the way a candle wick draws up wax. None of this is exotic engineering; it's a well-understood heating element, similar in principle to a hair dryer or a toaster element, just much smaller and repeatedly exposed to e-liquid rather than air.
Where metal exposure actually comes from
Because e-liquid contacts hot metal directly, trace amounts of metal from the coil wire can transfer into the vapor — a genuine, documented finding in analytical studies of vape aerosol, though the exposure levels found are typically far lower than from other common environmental sources. The amount varies significantly by coil material, coil age, and how hard the device is being pushed (higher wattage generally means more wear on the coil), which is part of why coil quality and replacement schedule aren't just about taste.
Why old coils taste burnt — and what that signals
A "dry hit" — the harsh, burnt taste from a coil that's run without enough e-liquid reaching it — happens when the wick can't keep the coil wet fast enough, usually because the coil is old, the e-liquid is too thick for the setup, or the device is being fired too rapidly in succession. Beyond being unpleasant, a scorched wick and coil are also the point at which metal transfer and degraded flavoring by-products are most likely to increase, so a burnt taste is a genuinely useful signal to replace the coil rather than push through it.
What actually reduces metal exposure in practice
A short list of ordinary maintenance habits addresses most of the avoidable variables:
- Replace coils on the schedule the manufacturer recommends, or sooner if flavor starts degrading — an old coil is the main driver of avoidable metal transfer.
- Prime new coils properly (saturating the wick before first use) rather than firing a dry coil, which causes early degradation.
- Match e-liquid viscosity (PG/VG ratio) to the coil and device, since a coil starved of liquid wears and degrades faster.
- Choose devices and replacement coils from established manufacturers, since coil material and construction quality vary and counterfeit coils are a known weak point.
Keeping it in context
This isn't a reason to assume vaping is equivalent to metal poisoning — documented exposure levels from well-maintained devices are low relative to many everyday sources. But it is a legitimate reason to treat coil replacement as a genuine maintenance task rather than a cost to delay, and to take a persistently burnt taste as a signal rather than background noise.
Sources: US Food and Drug Administration, Center for Tobacco Products device component research; peer-reviewed vaping aerosol composition studies as summarised by public-health bodies; World Health Organization, electronic nicotine delivery systems report.
Precise sources and clinical review are pending. Treat health claims as unreviewed and consult a qualified professional for personal guidance.