I still remember the time a customer wound up one of our customer services team by requesting a dual-triple horizontal-vertical kryptonite coil.
Perhaps because of the amount of coils coming in, she passed on the request to our product manager – to much merriment.
Or perhaps it was due to the sheer quantity of coils and tanks coming in at the time – and there’s been no shortage since!
- Essential glossary
- Style, material and longevity
- Wicking and Juice Holes
- New Coil Designs
- Building Your Own Coils
If aren’t already familiar with coils, you’ll find the following definitions helpful when reading this article!
BDC: Bottom Dual Coil
BVC: Bottom vertical coil
Cloud chasers: Vapers who like to create large clouds of vapour.
Mesh: Steel wire mesh, has great wicking ability
Ohms: Unit of resistance
RDA: Rebuildable dripping atomisers
Resistance: A measure (in Ohms) of how much an obstruction (the coiling wire) resists the flow of energy
Silica: High temperature resistant glass fibre, doesn’t burn like cotton does when dry
Wicking: The placement of material within, or around, a coil to keep liquid in contact with it
For more vaping terms see:
Each of the following materials is commonly used in coils.
Used in wattage mode.
- Can handle very high temperatures
- Easy to work with
- Readily available in many gauges to suit different build needs
- Very stable resistance
- Usable with every device
- No temp mode functionality
- Can cause a drop in flavour clarity after prolonged use, but generally pretty good.
- Can taste metallic when first installed
Ni200 (nickel, 99.6%)
Temperature control (or as I prefer, temperature limiting).
- The standard wire for temp control mods
- Resistance changes during heating are accurately predictable (this is how temp control coils work: they change resistance as they heat, the device picks up on this, and knows what temp they are at due to the change)
- Due to the the accuracy of the readings it gives a very consistent vape, in both performance and flavour
- At high temperatures, e-liquids base chemical elements can transform, leading to undesired formulas. This can help prevent that happening
- When building, tricky to work with due to the flexibility of the wire
- If not built with just the right amount of wicking, can lose consistency
- Only usable in temp mode, NOT to be used in wattage
- More prone to gunk build up
Wattage and temp control
- Very versatile working for both Wattage and TC Modes
- Easier to work with than Ni200 for temp coils, as it holds shape better
- Can last longer than a kanthal coil
- Heats very quickly, delivering a more instant hit
- Shorter ‘breaking in’ period than kanthal, less metallic taste
- Subjective perhaps, and may be different depending on liquid used, but many people say it has a cleaner, purer taste than kanthal
- Resistance fluctuates with heat, so less consistent in wattage/power mode
- More likely to suffer from ‘hot spots’ when building a micro coil (where each loop touches, hot spots arc the current across wraps rather than flowing through each one)
- Better performance when you can control wattage within a temp setting, than when wattage/ramp up is non changeable
Having gained more popularity since the release of the original sub-tank, the Aspire Atlantis, the vertical coil has now become far and away the norm in stock coils.
In a vertical coil such as the Aspire Cleito the coil stands upright, surrounded by a cotton wick. This allows for a direct airflow.
Couple this with a large core diameter, allowing more air to pass through quicker, and you start to see why they have become so popular!
This direct airflow allows the coil to have a consistent heat along its length, giving a more even evaporation of the e liquid. This in turn gives you a more consistent vape and flavour, and also reduces the risk of dry spots which can burn the wick.
But do vertical coils produce more flavour?
Technically speaking, the fact:
- that the liquid evaporates from the inner diameter of the coil (in the case of outer wicking)
- it has a smaller surface area
means it should produces slightly less flavour than a comparable horizontal coil.
However this is a controversial area and you’ll find many different opinions!
Perceptions are key here.
The vast majority of tanks readily available these days are sub ohm with vertical coils. Only a few have horizontal coils, which makes the comparison difficult to make.
However, tank users often say vertical tastes better, while RDA users prefer horizontal coils.
Design: Horizontal Coil
Due to the increased popularity of vertical coils, the horizontal design has become much less prevalent this past year.
Vertical coils can have either inner or outer wicking. However, you won’t find a horizontal stock coil with outer wicking, and it’s rare for DIY coil builders to use these too.
Due to the way that airflow passes up around these coils, if they’re not centered properly, there may be some performance variation between like for like coils. However, this is unlikely to be as noticeable when compared with DIY coils in an RDA placed incorrectly.
Spitback in Horizontal and Vertical Coils
Another contentious matter is spit back, when the coil occasionally spits hot liquid into your mouth.
Logic would say, due to the direct airflow, vertical coils would be the worst culprit. However, horizontal coils can also sometimes spitback as evaporation takes place on the outer edge of horizontal coils.
My personal tip for limiting this with any tank (opposite to some tips also found here!), is to fire it for a second or two before placing it to your lips. That’s because spitting generally occurs immediately after firing.
You can also adjust the power up or down, as different atomisers tend to spit more at varying voltages. Of course this isn’t always ideal, especially for cloud chasers! If their particular model spits more at higher power, they don’t want to turn it down!
Coil Design/Style Pros and Cons
This section I have found difficult to write, as there are so many variables between different atomisers and tanks.
This includes airflow, chimney diameter, the placement of the coil in comparison to the chimney, and so on.
Whereas a variable power mod is much the same as the next (quality and power aside, and for simplicity’s sake in this article…). You turn it up, you turn it down, and that’s about it.
Both styles can produce both really good flavour and vapour production, dependant on the above factors, and the subjectiveness of the user. My only advice here is to try as many as you can, and see which you prefer.
As a rule of thumb, vertical coil devices will be cooler and easier to draw. Horizontal coils will be warmer and have a slightly reduced airflow.
In flavour terms it’s generally thought, at least for tank users, that vertical coils perform better.
How Does Coil Design/Material Affects Longevity?
In general, vertical coils should last longer than horizontal coils because the more airflow keeps them cooler.
However, dual coil designs share the work-load between two coils, meaning a dual coil design will last longer than a single vertical coil design.
Wicking and Juice Holes
Wicking material can differ between cotton (organic, and unbleached), silica and mesh, but in stock coils the most widely used is cotton.
Cotton is a very good all rounder in regards to:
- vapour production
- the amount of liquid it can hold
- ease of use
Silica is used in more ‘old fashioned’ tanks (such as our H2 model) and previous CE incarnations, and is sometimes used by vaping enthusiasts as a preference.
Mesh is almost exclusively used in ‘Genesis’ tanks (so called after the original bottom tank/top coil design), and occasionally in RDAs.
If building coils yourself, it is important to get the amount of wick just right.
The general rule of thumb with wick passed through the coil, is to have a slight pull as you adjust the cotton back and forth, but no real resistance.
This leaves room for it to be soaked with liquid (expanding as it does so), without becoming so tight that the liquid cannot flow at a decent rate.
As a general rule, the higher the resistance, the less wattage you need for your tank to perform.
The lower resistance the more power you need, and the more vapour it will produce, though there are exceptions.
Higher resistance coils, generally in the 1-2 Ohm region, are primarily used for mouth to lung style vaping. These are best run (again this is a general rule, devices and coils vary in performance) within the 7-20w range.
These types of coils tend to heat slightly slower, are better suited to higher nicotine levels than sub ohm coils, and are best for those seeking more of a smoking like experience.
Sub ohm coils, those below 1 Ohm of resistance, are more suited to those who prefer a full on vape, an instant rush of masses of vapour.
The lower the resistance, the faster it vapourises liquid, due to a combination of surface area and the speed in which it heats, and the more powerful and safe a battery you will need.
Ni200 coils have what in wattage mode would be an extremely low resistance, something which could be potentially dangerous due to stress on the battery cell.
However, as they are:
- absolutely not designed for this mode,
- temp control devices use this resistance to tell what temperature the coil is, keeping it well within tolerances
it is perfectly safe to use as a temp control wire.
New Coil Designs
Since I first wrote the article A Vapers Guide to Coils, many things have changed in the world of vaping, progression and all that. As such, here’s a little update on what’s happening in the coil market at the moment.
Firstly, and this is a bugbear of mine being a stickler for facts, they’re generally not actually made of mesh. They are usually made of thin pressed metal, with holes punched through, giving a vague appearance of mesh and frankly that of a cheese grater/shredder (depending on your use of the English language). I personally would call them something like a punched heating element, or an aerated heating element. Mesh itself is primarily used as a wicking material, which we shall cover further on in the article.
As you can see from this image of a V12 Prince atomiser, the material (kanthal or stainless steel dependant on atomiser) is set in a C shape around the inner of the wick, each side linking to the base of the atomiser making the positive and negative connections. It covers the vast majority of the surface area of the wick, offering decent vapour production, which in turn produces an improved flavour, although of course taste is subjective. As I write this I have the Cleito Pro “Mesh Coil” (compatible with all previous Cleitos except the 120) with our Forest Fruits shortfill e-liquid. While for me personally there’s only two coils we stock that outperform it for flavour (both by Aspire actually, Cleito EXO and Revvo coils), the ease of filling with this tank has won me over!
As the element has lots of mass, you would think that ramp up time (the time it takes to heat to performing temperature) would be slow, but this isn’t really noticeable with these elements.
So far for me they have an excellent longevity of usage, as long as you don’t chain vape constantly, they should last you a considerably longer time than regular wire coils. My current coil has lasted nearly twice as long before starting to dip in performance. This is likely due to the aforementioned mass, as the workload is being spread over a larger area, plus the gunking of the coil (when you get a build up on the coil after usage) is also spread thinner.
For more information see our post on Mesh Coils.
Multiple Coil Atomisers
Smok were the manufacturer to pioneer this corner of the market, with their Beast series of tanks and atomisers. The theory with a multiple coil head is the same as the mesh style atomiser; they aim to maximise the surface area contact between wick and coil, which in turn maximises the potential vapour and flavour production.
There are however a couple of potential pitfalls with this design if you chain vape, due to wicking capabilities and having multiple coils.
Wicking happens through holes on the outer of the atomiser. If the wick itself is dry it takes time to feed through to the centre of the atomiser, and chain vaping may not allow time for this to happen, resulting in dry hits.
Because the coils come in multiples, they only work as well as the worst coil, and you also multiply the chance of one of the coils being of lesser quality. Four coils? Four times the chance of purchasing a duff one.
Another technique used to maximise surface area is the parallel coil. Essentially it’s two or more lengths of wire wound together into a coil, so rather than having multiple individual coils, you have the same amount of material in a single coil.
For me, this is a better option than the multiple coil atomisers for many reasons.
- For direct inhalation tanks you have the potential to maximise airflow through the single coil, helping to keep the atomiser cool.
- Having the one coil negates the trouble you may suffer in wicking when having multiple coils, as the wick is directly against the outer wall of the atomiser itself.
- Multi coil atomisers don’t tend to utilise as much surface area. That meanshey’re not as efficient as a single coil where the heating element touches a larger percentage of inner exposed wick.
The final point is worth further explanation.You have a dual coil atomiser head, using the same exact wire, resistance and diameter of coil as a single, parallel coil. The dual coil head covers the same amount of area, however with the two coils within each other of the parallel coil, you have half the exposed wick covered by the same amount of heated element.
On the flipside of that, you of course get double the airflow with a dual coil of the same diameter. Generally, manufacturers would use different resistance material to allow for a larger diameter single coil at the same resistance, giving a larger diameter and negating this difference in airflow.
Apire Revvo Coils
One last thing worthy of mention, is the Revvo ARC or Aspire Radial Coil. Again we have the metal with punched holes thing going on, originally sported by the Notch Coil from Wismec, but this time it’s the flat design with wicking below that’s rather different.
Having the full surface of the wick open to the tank below, this has to be one of the best wicking atomisers on the market, as long as you tilt it often enough to ensure that the liquid makes contact with the wick itself.
One negative of this design, if left on its side the liquid eventually floods the wick and passes through, allowing the liquid to run out of the upper section of the tank. In essence, stored upright and tilted during use (both of which most vapers tend to do without any forethought), and you have an excellent performing tank.
Please note that there are risks when you start coil building and modding. We take no responsibility for any issues that arise should you start coil building.
This section should be taken purely as an introduction, and there are links to more detailed guides for those interested.
Coil Building Safety
Before embarking upon building your own coils there is one major thing to remember!
Check the resistance of any coil before firing it, using either a dedicated ohm meter, or a regulated device that will show your resistance.
There are two reasons for doing this.
- Ensuring that the resistance is within your devices limits.
- Ensuring that the coil doesn’t short, which can lead to serious battery failure and injury.
I once killed an £80 device by forgetting this golden rule, and I wasn’t even building a fresh coil, but simply re-wicking an old one.
If it wasn’t for the fact my batteries were easily and quickly removable, it could have been much worse!
Building your coils
When building your own coils, it is important to consider exactly what type of vape you desire, and to tailor your build to suit.
Using a coil building app or website (such as www.steam-engine.org) can help greatly in choosing the correct wire and gauge.
The space you have to work with, and the number of coils you are able/wish to use, can help determine what wire is best.
If you prefer a 0.5 Ohm build and have both a restricted decked single coil device, and a dual coil larger deck, then a different type of build is required. A dual coil build halves the resistance. So to achieve the same result, you would need to double the resistance in each individual coil of the pair.
A smaller single coil using kanthal wire @0.5 Ohms would need 6/5 wraps of 26awg (AWG = American Wire Gauge) kanthal. Using the same gauge wire you would need double the wraps for a dual coil, making the coils possibly too wide.
A larger dual coil using kanthal wire @0.5 Ohms would perhaps have 9/8 wraps of the higher resistance 28awg. The larger area should then produce more vapour, yet the larger mass of metal may slow ramp up time. In this example, it shouldn’t make a very noticeable difference.
As a rule of thumb, spaced coils (where the loops do not touch) are better for temp control vaping, due to there being no risk of hot spots, and micro coils (where each wrap sits flush to the next) is preferred in wattage mode.
As mentioned, this was an introduction to coil building. If you are interested in going further, here are a few resources to get you started!
Getting Started Building Your First Coil: God of Steam posted a good guide to building a spaced coil (the style used in temp mode).
Kayfun 3.1 Microcoil and Cotton Guide: ECF member Romelee posted this guide to building on a Kayfun, a rebuildable tank that has a similar deck to many, with this guide being more for coils used in wattage mode.
Subtank Mini Nickel Build: Finally, check out a great video showing how to rebuild the Subtank Mini for temp control, posted by Vaping Pauly.