What is spit-back?Spit-back, in vaping parlance, is when a coil spits a tiny amount of hot liquid into your mouth when you initially take a puff.
How does spit-back occur?Imagine placing a frying pan on high heat without any liquid on and leaving it till it’s above one hundred degrees celsius. If you then flick water on it, it will spit violently.
The liquid vapourises so fast it turns into a bubble which bursts, throwing hot liquid in every direction.
This, in essence, is what’s happening when you hear the tell-tale popping sound when you initially fire some coils.
An over saturated coil should not cause spit-back. Let’s go back to the frying pan analogy.Flicking a small amount of liquid will cause it to spit. However, if you pour in a jug full of water the larger amount actually subdues the forceful reaction. The same principle applies here.
Is spit-back dangerous?The most harmful thing about spit-back is the shock of it going “pop” just as you put it to your mouth. The low levels of nicotine in a single drop wouldn’t cause any harm - research by Bernd Mayr has found that the danger from nicotine has been vastly exaggerated, while an evidence update by Public Health England states:
"When used as intended, EC [electronic cigarettes] pose no risk of nicotine poisoning to users".
That is also true with the heat. Due to the tiny amount, as long as you have saliva, the e-liquid will cool instantly in your mouth.If the device is pointed at your face and not in your mouth at the time of firing, the speck of hot liquid might cause a very mild burn, but should do no damage. It would be much less harmful than the water in my frying pan analogy, which itself should cause little more than a sucking of air through your teeth and mild swearing.
How do you prevent spit-back from occurring?As spit-back occurs within the first milliseconds of firing a coil, preventative action is the best way to deal with it. Simply point the tank away from you as you initially fire it, the pop will occur, then you can vape with ease.If you have a device with adjustable power, and the popping happens on a regular basis, I would recommend turning it down a notch (or 10 dependant on power rating). A slower heating of the liquid should not cause the reaction which produces spit-back.
Are there any other solutions to this problem?Some vapers believe that the draw of your vape can affect the likelihood of spit-back. If you reduce the airflow enough to actually draw more liquid through the wick, the extra liquid should help prevent the effect. However, you then run the risk of over saturating the wick completely, which can cause the coil to flood.
Another alternative would be spit-back protection. Some drip tips have inbuilt ways to stop direct hot spits of liquid, by either partially or fully blocking the direct path. One solution is a perforated area above the coil (generally within the drip tip itself) to disturb the flow greatly, and better again is a complete closure of the path as with the Joyetech Ego AIO drip tip, which has an inner 360 degree plastic spiral. In essence, if you can look down the drip tip and not see the inner of the coil, you should be good.
If you have a device which has variable ramp up times (an adjustment mode which allows slower heating of the coil), then utilising this could be of real benefit also. The Smok Species for instance, has the options soft/normal/hard/max. Lowering this with a troubled tank could ease matters.
Have you had problem with spit-back? What solutions did you find useful? Let us know in the comments!
E-cigarettes: an evidence update Public Health England
Mayer B., How much nicotine kills a human? Tracing back the generally accepted lethal dose to dubious self-experiments in the nineteenth century Archives of Toxicology (2014) 88: 5. https://doi.org/10.1007/s00204-013-1127-0