How is a coil built?
What’s it like to switch from pre-made coils to personally built coils? This section explains what to expect when building coils.
What is needed:
When a first rebuildable atomizer is purchased, consider buying a coil building kit as well. A coil building kit consists of many of the below items, along with many other useful odds and ends. These are the most important items for coil building.
- Kanthal wire
- Organic or pesticide-free cotton
- Resistance meter with 510 threading
- Coil winder, drill bit, or precision screwdriver set
- Wire cutters
- Ceramic tweezers
Building a simple Atomizer coil
When building coils, the possibilities for complex and elaborate designs are nearly limitless. Many tutorials for complex coil builds can find on YouTube. These steps can be used as a guide in creating a simple dual-coil build on an RDA designed to accommodate two coils, but should certainly not be the only knowledge going into building.
- Connect the RDA to a resistance tester. A resistance tester for vaping provides a convenient platform that holds the RDA in place while built.
Cut two equal lengths of kanthal(start with 24G or 26G) wire around 6-8” each.
- Use a coil winder to wrap the two lengths of wire into coil shapes. The wire can also be wrapped tightly around a small drill bit or precision a screwdriver. The two coils should be identical and should have about 5-7 loops each. Each loop increases the surface area of the coil while also increasing the coil’s resistance. With experimentation, a sweet spot will be found. Insert the leads of the coils into the holes of the rebuildable atomizer. Tighten down the screws while holding the coils in place to keep their positioning even.
- Use the wire cutters to trim the coil leads as close as possible to the RDA’s mounting posts.
- Turn on the resistance tester to check the resistance of the RDA. If the coil’s resistance is within a safe expected range, continue. If the resistance differs significantly from expected, or the resistance tester shows a short, troubleshoot that issue before continuing. Most likely, metal is touching metal in a place where that should not occur. If a short is encountered when one is new to coil building, the coils should probably be removed and discarded, allowing for a fresh start.
- Remove the RDA from the resistance tester and connect it to a vaping device. Set the vaping device to a low wattage.
Press the fire button on the vaping device in brief pulses until the coils glow dull orange. Between pulses, use some ceramic tweezers to adjust the coils until they glow evenly. If the loops of the coils are pulled or wrapped apart, it will be easier to make them glow evenly. However, coils with spaced loops may occasionally pop loudly during vaping. If the loops are pushed together, the coils will pop less, but it may be more difficult to get them to glow evenly. If a section of either coil glows extremely brightly, that’s a hot spot. All hot spots will need to be eliminated before continuing. Make sure the legs are on each coil are the same lengths and make sure the coil spacing is even. Sometimes a light “sweep” over the coil with tweezers will help.
- Wash any dirt or oils from hands and cut two 1-2” lengths of organic cotton. Roll the tip one end of cotton between the pointer finger and thumb thumb until the end is small enough to thread through the middle of a coil. Repeat with the other coil. The correct amount of cotton is being used if a slight resistance is felt when pulling it through the coil. If no resistance is felt, not enough cotton was used. Cut a slightly thicker piece and try again. If the cotton can not go through without deforming the coil, too much is being used and should be attempted with a thinner piece. Cotton expands when it’s wet so the right resistance is key.
Trim the cotton so that both ends of both wicks will just touch the drip well at the bottom of the RDA. Gently fluff the ends of the wicks with the ceramic tweezers and tuck the ends under the coils. Some of the cotton and be “plucked” from the ends to allow for more room in the chamber and quicker juice flow from the deck. Just be sure not to remove any from within the coil itself.
Wet the wicks thoroughly with e-liquid. Allow a few moments for the e-liquid to soak completely into the wicks. A toothpick or pin can be used to “jiggle” the cotton but be careful not to crush the “fluff” of the cotton. Crushing the cotton will slow the slow of e-liquid to the coil.
- Press the fire button on the vaping device to test the RDA. The RDA should produce vapour. Since the wicks are wet, the coils should not glow. If everything looks correct, the top cap can be placed on the RDA and proceed with being vaped.
TYPES OF WIRE
What wire types can be used for coil building?
Kanthal is the most common wire for vaping. Kanthal has a moderate resistance and lasts a long time, even with repeated heating and cooling. Kanthal also produces a predictable flavour since it’s the wire type that most people already use and are used to.
Compared to kanthal, nichrome has a much lower electrical resistance. Because nichrome is less restrictive to the electrical current than kanthal, nichrome coils can heat up much more quickly. That’s why nichrome is a popular choice for the exotic wires we’ll discuss shortly. Most people detect little to no flavour difference between kanthal and nichrome coils. However, nichrome contains nickel and isn’t appropriate for those with nickel allergies.
Stainless steel has become an extremely popular choice for vaping coils because it has a low resistance and heats quickly while creating a pure flavour that people love. Although stainless steel’s resistance is high enough that it can work in a vaping device’s standard wattage mode, most modern devices can also use stainless steel coils in temperature control mode.
Nickel is an extremely low-resistance metal that isn’t safe to use in wattage mode. It’s appropriate only for temperature control mode. Nickel changes greatly in resistance when it’s heated, and temperature control devices use the change in resistance to estimate the coil’s temperature. Because nickel has a high temperature coefficient of resistance, temperature control vaping devices can estimate its temperature very accurately.
Nickel does have a few drawbacks as a coil building material. The first is that nickel tends to snap back to its original shape when bent. The second is that, for some people, nickel produces a metallic flavour. The final drawback is that a nickel coil cannot be test fired to check for hot spots as would be done with kanthal, nichrome or stainless steel. When nickel glows, it releases toxic gas, and therefore will need to be wrapped with spaced coils to avoid hot spots.
Titanium is a second coil material for temperature control vaping. Titanium is very inert at lower temperatures, and some people find that its flavour, when vaping, is less metallic than that of nickel. Titanium is a suitable coil material for those with nickel allergies, and titanium coils are a bit easier to build than nickel coils. Titanium does, however, have some of the same drawbacks as nickel. Titanium can not be dry fired because it forms titanium dioxide when heated too much, which is VERY unsafe to inhale. As with nickel, spaced coils will need to be wrapped when using titanium.
Building tutorials on YouTube, will show coils made using wires with exotic names like Clapton
. The names refer to coils made using multiple twisted, wrapped or braided wires. People create these exotic wires because the resulting coils have a very high surface area, and as mentioned at the beginning of the article, more surface area means more vapour. As experience is gained in coil building this can be attempted by anyone, but pre-assembled wire like claptons are available in spools, and even as pre-built coils, for those not wanting to take all the time and effort.
TYPES OF WICK
What wick types can be used for coil building?
Cotton is the most popular material for vaping wicks. Many people like the Japanese organic cotton pads that are available in many cosmetics stores. Other pesticide-free cotton can be found marketed as a vaping product under brand names such as Cotton Bacon
and Native Wicks
. Cotton is inexpensive and easy to use. It carries liquids efficiently. As long as it doesn’t burn, cotton produces a clean and fairly neutral flavour. Cotton can burn when it is dry, though, so keeping a cotton wick properly saturated when vaping is very important.
Rayon can be found for sale in beauty supply stores under the CelluCotton
brand. Out of the box, CelluCotton
has a somewhat wick-like shape, so working with it is fairly easy. Rayon does present a bit of a challenge, though, in that it contracts when it’s wet. Cotton expands when it’s wet, so one must be careful not to use too much cotton when wicking a coil with it. With rayon, though, one must stuff as much material into the coil as possible. Rayon is an extremely efficient carrier of liquid. Some people find it so efficient, in fact, that they trim it at an angle to minimize the amount of material that touches the drip well at the bottom of the atomizer.
Opinions vary about the flavour quality of rayon as a wick material. With rayon, not as much time is needed for the wick to re-saturate between puffs compared to cotton. Some people feel that rayon has a plastic flavour, while others find the flavour to be more neutral than cotton. A rayon wick can burn if it’s dry so saturation is important, but rayon is slightly more tolerant to heat than cotton.
Until sub-ohm vaping became popular among mainstream vapers, silica was the most popular wick material for vaping. Silica is very resistant to heat; a coil can’t burn it. Although a few people dislike the flavour of silica wicks, most find that it imparts a more neutral flavour than cotton. Silica wicks aren’t as popular as they once were because aren’t as efficient as cotton wicks. Silica in a sub-ohm vaping setup optimized for big cloud production may not be the best choice as a wick material. Silica does, however, work well as a wick if a lower-temperature mouth-to-lung setup is used.
Building a coil with a silica wick presents a bit of a challenge because silica can’t squish between one's fingers as it would with cotton. The coil will have to be wrapped around the silica wick, instead of threading the wick through the pre-wrapped coil. Silica is also very fragile despite its tolerance to heat. If the ends of the wick begin to fray, the wick will quickly crumble. Some people torch the ends of silica wicks to fuse the fibres together.
Although sintered ceramic wicks for pre-built coils have been around for a while, there is at least one company that makes ceramic rope wicks for coil building. Kiln treated for durability, a ceramic wick is so impervious to heat that it makes it possible to clean a coil by dry burning without removing the wick. Just fire the coil until the gunk burns away and return to vaping. An additional benefit is that many people believe ceramic has the most neutral flavour of all wick types. As with silica, ceramic rope can not be threaded through a coil; the coil must be wrapped around the wick. An additional drawback of ceramic is that it isn’t an efficient carrier of e-liquid. Although ceramic wick can be used with a sub-ohm coil, it will take several seconds after each puff for the ceramic to re-saturate with e-liquid.
Stainless steel mesh was once a popular wick material among advanced vapers. Steel mesh has a very neutral flavour and very efficient capillary action. The drawback of steel mesh is that it doesn’t work well with the rebuildable atomizers that most people use today. Stainless steel was most popular as a wick material for a tank called the Genisis – sometimes misspelled “Genesis” – that was common several years ago. The typical Genisis setup used a single vertical coil wrapped around a stainless steel wick that brought e-liquid up from a reservoir positioned below the coil. Although steel mesh is an extremely effective wick material, it is difficult to use because steel is conductive and could cause a short if it isn’t prepared properly.
To prepare steel mesh for use as a wick, one must repeatedly heat and quench the steel to create a non-conductive layer of oxidation. It’s also difficult to wrap a coil around a stainless steel wick. If any gaps exist between the coil and the wick, the coil will have hot spots. Even today, though, there are many Genisis tank owners who faithfully go through the lengthy ritual of preparing stainless steel wicks because they firmly believe that nothing else provides a better vaping experience.
Hemp isn’t a particularly common wick material, but it is popular with a small subset of the vaping community because it’s an all-natural material that’s a bit more heat resistant than cotton. Choose hemp that has been thoroughly cleaned to remove all gums, resins and pesticides.