What is coil gunk and how to stop it?

What is coil gunk and how to stop it?

Once you have been vaping for a while, you will defiantly come across the issue of coil gunk. Which neatly leads to the lifelong question of why?

Some of flavours and sweeteners used in e-liquids don’t always vaporize fully and they can sometimes leave residue on your coil. The more e-liquid you use, the more quickly that residue forms. A modern sub-ohm tank goes through e-liquid extremely quickly. This brings up the question: – Why are my coils turning black and going gunky?

What is coil gunk?

The blackness or coil gunk is the carbonized remains of e-liquid additives such as flavours and sweeteners. This blackening can sometimes begin to appear after your first full tank full of liquid, depending on the makeup of the juice.

As you continue to vape, you can watch as the coil turns from silver to brown. Then eventually to a deep, glossy black. In some instances the transition from silver to black in less than 24 hours.

What is coil gunk and how to stop itAs the crust on your coil becomes thicker, you’ll notice the following changing in performance.

Increase in Sweetness

At first, the e-liquid begins to tastes a bit sweeter. This is because the sweeteners that are used in the blended e-liquids begin to build upon the coil and cotton. Due to the fact that the sweeteners tend not to vaporise at the same rate as the other ingredients in the e-liquids.

Reduction in Flavour

As the residue becomes thicker, it starts to caramelize. Your e-liquids begin to taste less sweet and take on a distinct “burned sugar” note.

Reduction in Wicking

As you continue to vape away, the coil gunk can become so thick that it will begin to restrict the ability of the cotton to do its job. Then the capillary action of your cotton wick will reduce and the cotton gets saturated with this caramelise gunk. Even though the cotton is in contact with the e-juice, fresh juice won’t be getting to your coils. Plus the remaining juice next to the coil will begin to cook.

What causes coil gunk?

Almost everything in an e-liquid – including the vegetable glycerine (VG) that most e-liquids contain – leaves some residue on a coil. Some e-liquid ingredients, however, encourage the formation of coil gunk more quickly than other ingredients. Minimizing your usage of those ingredients can help you prolong the life of your coils.


Sweeteners such as sucralose cause coil gunk more quickly than any other e-liquid ingredient. Almost everyone loves sweet flavours, and e-liquid makers have responded to that demand by sweetening most of their products.

Natural Tobacco

Natural tobacco extracts often contain tiny solid particles that collect on a coil and form a layer of crust. If you like NET e-liquids, it’s wise to ask the makers about the filtering processes they use. Although filtering doesn’t remove all of the solid matter from a tobacco extract, it does help. A poorly filtered tobacco extract will kill coils very quickly.

High – VG

Many vapers find that high – VG e-liquids cause coil gunk much more quickly than e-liquids containing mostly or all PG.

What is coil gunk and how to stop itFlavouring

Some flavouring compounds may contribute to the formation of coil gunk. E-liquid manufacturers guard their recipes closely, though, so it’s difficult to say which flavours are the culprits.

How to stop coil gunk?

One of the ways is to simply change your cotton and dry heat your coils after every tank full of juice. Of course, that can be a massive pain. Also, you may find that you need the wick your cotton a bit looser to help too.

The other option is to try and stay away from juices that use high levels of sweeteners or tobacco juice that has been poorly filtered.

If you love your favourite e-liquid too much to consider using anything else, the other way to reduce coil gunk is by switching to a vaping setup that consumes less e-liquid. A pod vaping system or a mouth-to-lung set up, where inhaling uses drastically less e-liquid than a box mod with a big sub-ohm tank.

If you continue using the sweetened e-liquids that you’re using right now, you’ll still deal with coil gunk after switching to a lower-power vaping device. It’ll take much longer for the gunk to form since a lower-power device uses less e-liquid.

I think coil gunk is just one of things that you have to deal with when vaping. You soon get to know which brands of e-liquids use more sweetener than others, and to be honest you just tend to stay away from those flavours. Don’t get me wrong it does mean that you can’t have your favourite flavour anymore. It just means that you may need to switch brands. I can vape 60ml of sweet vape and the coils look like new, due to the type of flavour and sweetener that they use, and others after about 5ml the coil and cotton it dead. It really is just about finding what works well in your set up.

Dan Pierce

I’m a Blogger based in UK. I stopped smoking in October 2013, at which point I set up my own Vaping review blog, www.myvapingreviews.co.uk to help me record and share my Vaping journey. A real hobbiest Vapor, who not only enjoy the Vaping experience, but love the technology and design behind it.