Coils, also called atomisers or coil heads, are a vital component of any e-cigarette device. The ‘mod’, or battery component of your e-cigarette sends an electric current through the coil which heats the wire which in turn heats the e-liquid in your tank or pod, turning it into vapour that you inhale. Think of it like an element in a kettle for heating water.

The coil really refers to the conductive wire that carries the electric current from the battery and was traditionally shaped like a spiral coil to allow the current to contact the wicking material, usually cotton, that is in contact with the wire. These days, coils come in many different forms including mesh, and multiple coil formations. Coils can also come in a variety of materials including stainless steel, kanthal wire, ceramic and titanium. These all produce a different quality of vape experience, affecting the flavour and vapour produced.

All coils specify their electrical resistance in ‘ohms’. Standard resistance coils usually range from 1.0 ohms to 3.0ohms. Coils with a resistance below 1.0ohms are known as ‘sub-ohm’ coils and can range from 0.9ohms to 0.1ohms and lower.

A curious quirk of physics means that higher resistance coils require a lower power output from the battery, while low resistance, or sub-ohm, coils require a higher output from the battery. The result is small-to- moderate vapour from a high-resistance coil and low-powered device and great clouds of vapour from sub- ohm coils and more powerful devices. Knowing which style of vaping your e cigarette device is built for should give you a quick idea of the type of resistance, and the number of displayed ohms, your new or replacement coil should carry.

You’ll often see e-cigarette devices and their associated coil heads described as being ideal for either MTL or DL vaping. MTL is short for Mouth-to-Lung, which is a style of vaping most akin to smoking traditional cigarettes; where you draw the vapour from your device and hold it in your mouth for a moment before inhaling into the lungs. DL vaping stands for Direct-to-Lung and involves drawing the vapour straight into the lungs for absorption.

MTL vaping is most commonly associated with high-resistance coils and devices that produce relatively moderate amounts of vapour, and where the action of holding vapour in the mouth before inhaling produces a more comfortable vape. Eliquids commonly used with these types of coils are high-PG, 50/50 and nicotine salts.

DL vaping falls into sub-ohm territory, where great clouds of vapour are produced from low-resistance coils and more powerful devices, but usually of a strength and intensity that is comfortable to inhale directly into the lungs. High-VG e-liquids are most commonly used with these coils.

Depending upon the frequency with which you vape, coils should be replaced when they fail to produce the required flavour or vapour. A spent coil might begin to taste a bit strange or stop producing vapour. How long a coil lasts can depend upon the materials it’s made from, the device – high or low powered – it is used with, and how frequently it is ‘fired’, or vaped. Heavy, sub-ohm users may need to replace a coil every week, while moderate to light users may only need to change a coil, or prebuilt pod, every 1-4 weeks.

The type of liquid you use with the coil can also affect its lifespan. High-VG e-liquids of the sort used for sub- ohm vaping tend to be quite thick and can gum up coils with heavy use necessitating frequent replacements.