Vape coils are made of resistance wire, most commonly Kanthal (an iron-chromium-aluminum alloy), nichrome (a nickel-chromium alloy), or stainless steel. The wire is wrapped or shaped into a coil that heats up when electricity passes through it, vaporizing the e-liquid soaked into a wick sitting inside or alongside the coil. The wick is usually organic cotton, though rayon and ceramic options exist too.
The Three Main Wire Types
Kanthal A1 is the most widely used coil wire. It’s a ferritic alloy made of about 22% chromium, 5.8% aluminum, and the rest iron. It’s popular because it’s inexpensive, holds its shape well, and has high resistance per length of wire, making it easy to build coils that hit a target resistance. The tradeoff is that Kanthal only works in wattage mode, not temperature control, because its resistance doesn’t change predictably as it heats up.
Nichrome 80 (often called Ni80) is an alloy of roughly 80% nickel and 20% chromium. It heats up faster than Kanthal and has slightly lower resistance, which gives it a quicker ramp-up time. Many vapers prefer it for flavor. Like Kanthal, it’s primarily a wattage-mode wire, though some temperature control systems can work with it. The high nickel content is worth noting if you have a nickel sensitivity.
Stainless steel 316L is the most versatile option. It resists corrosion at high temperatures, works in both wattage and temperature control modes, and produces clean flavor. Its resistance changes in a consistent, predictable way as it heats, which is what makes precise temperature control possible. SS316L contains nickel (around 10-14%) and chromium as part of its alloy, so it’s not nickel-free, but the amount is lower than in nichrome wire.
How Wire Gauge Affects Your Vape
Coil wire comes in different thicknesses measured by American Wire Gauge (AWG). Thinner wire has a higher gauge number and more resistance. For Kanthal A1, a 28-gauge wire has about 0.4 ohms per inch, while a thinner 34-gauge wire runs around 1.8 ohms per inch. Thicker wire (lower gauge) heats more slowly but can handle more power. Thinner wire heats quickly but burns out faster. The gauge you choose, combined with the number of wraps and the coil’s inner diameter, determines the final resistance of the build.
Mesh Coils vs. Traditional Wire Coils
Mesh coils use a flat, grid-like strip of metal instead of a wound wire. They’re typically made from the same alloys: Kanthal, nichrome, or stainless steel. The key difference is surface area. A mesh strip contacts far more of the wicking material at once compared to a round wire coil, which means more e-liquid gets heated simultaneously. This produces more vapor and more even heating, reducing the chance of hot spots that can scorch the wick and create a burnt taste. Most pre-built coil heads in modern sub-ohm tanks now use mesh designs for this reason.
Wicking Materials Inside the Coil
The wick draws e-liquid into the coil through capillary action. Organic cotton is by far the most common choice. It’s cheap, easy to work with, doesn’t add off-flavors, and performs well across a wide range of builds. Japanese organic cotton pads are a popular specific product among coil builders.
Rayon, often sold under the brand name CelluCotton, is spun from chemically treated wood pulp. Its fibers are much finer than cotton’s, giving it stronger capillary action and faster wicking. It handles high-wattage vaping well because it stays saturated more efficiently.
Ceramic wicks come in two forms: a soft rope made from woven fibers that are heat-bonded together, or sintered ceramic, which is powdered ceramic that’s molded and heated into a solid porous structure. Ceramic wicks last longer than cotton and tolerate higher temperatures, but they’ve drawn scrutiny over whether tiny ceramic particles can break loose and be inhaled.
Metal Exposure From Heated Coils
Heating metal hundreds of times releases trace amounts of that metal into the vapor you inhale. A study published in Environmental Health Perspectives measured metal concentrations in e-cigarette aerosol and found that chromium, nickel, lead, manganese, and zinc were all present. The concentrations varied widely between devices, but roughly half or more of the aerosol samples exceeded health-based exposure limits for chromium, manganese, nickel, and lead.
Lead was a particularly concerning finding because it isn’t a listed component of any standard coil wire. Researchers believe it’s present as a trace contaminant in the metal alloys or solder joints. Lead concentrations in the aerosol were more than 25 times higher than in the liquid sitting in the tank, confirming the coil itself as the source. Zinc showed a similar spike.
Coil type matters too. A 2025 study in Inhalation Toxicology compared ceramic and mesh coils and found distinct heavy metal profiles for each. Ceramic coils released higher levels of magnesium, aluminum, chromium, manganese, iron, nickel, arsenic, and titanium. Mesh coils released more copper, cadmium, lead, and tin. Researchers detected corresponding metals in the exhaled breath of participants, and the metal profiles differed significantly depending on which coil type a person used.
Nickel Sensitivity and Coil Choice
Nickel allergy affects a significant portion of the population, and two of the three main coil materials contain substantial amounts of nickel. Nichrome is 80% nickel. Stainless steel 316L contains 10-14%. Even Kanthal, while nickel-free in its formulation, can contain trace impurities. If you have a known nickel allergy, Kanthal is the safest wire choice.
Nickel allergy typically causes skin reactions: itching, rashes, hives, dry or cracked skin. Symptoms usually appear within 12 to 72 hours of exposure. But inhaling nickel-containing aerosol is a different exposure route than skin contact, and the health implications are less well understood. Systemic nickel allergy syndrome, which occurs when nickel enters the body rather than just touching the skin, can cause headaches, fatigue, and digestive symptoms. A patch test administered by a healthcare provider is the standard way to confirm a nickel allergy.
How Coils Are Regulated
In the United States, vape manufacturers must submit a Premarket Tobacco Product Application (PMTA) to the FDA before selling their products. The application requires detailed disclosure of coil materials, including the number of heating elements, wire gauge, resistance, operational and maximum temperature, and the specific material used. Manufacturers must also provide test data with quantitative acceptance criteria for each of these parameters.
That said, the PMTA process doesn’t ban any specific coil material outright. It requires manufacturers to document what they use and demonstrate that their product is “appropriate for the protection of the public health.” The burden is on the manufacturer to prove safety, not on the FDA to pre-approve a list of acceptable metals. Products sold without PMTA authorization, which includes many devices on the market, bypass this scrutiny entirely.