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 meshed, 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
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,
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.
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 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.
How Does Coil Design/Material Affects Longevity?
In general, vertical coils should last longer than horizontal coils because the more airflow keeps them cooler.
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.
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.
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.
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.
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.