It can happen that your e-cigarette spits liquid into your mouth, generally accompanied by popping, which novice vapers find concerning. There is no need to worry, however: there is a simple explanation for this phenomenon.
An explosion, and not just of flavours
Just as you were taking a leisurely puff from your vape, a small explosion, not unlike a Christmas cracker, occurs, you hear “pop”, and you can feel some droplets in your mouth. An experience that is as unpleasant as it is unexpected. However, there is no reason to be concerned.
For various reasons that we will get back to later, liquid can accumulate in and at the top of your resistance coil, causing it to become saturated. When you press the trigger button, your resistance coil will heat the liquid.
However, if there is liquid saturation, the amount present will exceed the capacities of your resistance coil. The nearest portion will heat up, expand and evaporate, in line with the laws of physics, but the most distant portion will not heat up as quickly, remain in the liquid state, and a bubble will be formed.
When the pressure applied by the vapour is greater than the resistance of this layer of liquid, this bubble bursts, causing a pop, and the vapour will rise in the tube, pushing the liquid in front of it, causing spitting. The whole process is very quick.
Why does saturation occur?
There are a number of reasons why a liquid might saturate your resistance coil.
A resistance coil consists of a heating wire and absorbent fibre wadding. When the wire heats, it causes the liquid impregnated in the wadding to evaporate.
Eventually, this fibre wadding collapses under its own weight, when the resistance coil starts getting worn, and the liquid infiltrates through the gap created. A minor manufacturing defect can sometimes mean that your resistance coil contains less fibre than envisaged, and once again, the space that it should have occupied is engulfed with liquid.
Finally, no wadding is ever perfect. Each one has its own characteristics, particularly based on its absorption capacity, which is determined according to the thickness of the liquid. The thicker a liquid is, the more absorbent the wadding will need to be, and vice versa. The most commonly encountered liquid saturation scenario is when the liquid is too runny for the resistance coil. It flows too easily and is not stopped.
Another, slightly different, phenomenon explains the accumulation of liquid: the combination of an overly narrow tube and too much power. Not all the vapour produced by the resistance coil passes through the tube, and the non-absorbed vapour is cooled, condensed, turning back into liquid, and blocks the tube until the next activation, where the pressure will spit this “plug” into your mouth.
Finally, you might simply be pulling too hard on your vape. It is your inhalation that actually draws liquid into your resistance coil. And if you pull too hard, you will saturate it.
In any case, it’s nothing to worry about: don’t pull so hard, replace your resistance coil or change liquid, in any case, don’t hesitate to turn to your vaping store where you will get advice on what the problem is.
NB: this article is not applicable to rebuildable devices, even though some principles are similar.