Why Does Vape Juice Turn Dark?

So, there’s few reasons as to why you’d be here reading this. Maybe you’ve just bought two bottles of juice, and one of them is darker than the other, maybe a little yellow. Or perhaps you’ve bought a new bottle of juice that’s suspiciously lighter than the older one you have. It could be that you’ve left half a bottle off to the side while you enjoyed a new flavour, only to come back to it turning brown. Maybe you’ve gone on a weekend away and left the vape at home, coming back to brown juice in your tank. Vape juice turns dark over time, here’s why.


Oxidation. It turns iron rusty, makes beer taste like cardboard, makes bananas turn black, in humans it damages the molecules in DNA, and it turns vape juice dark.

Oxidation is a chemical reaction, and it just so happens that nicotine is very reactive. Exposing it to oxygen or even light can change the colour of the vape juice into a yellow, then brown.

The same thing happens to a sliced apple – ever cut an apple into slices, ready for a juicy treat then walked out of the room for a few minutes, only to come back to brown patches on the slices?

Oxidation in vape juice is very normal, and you should expect it to happen even if there’s low amounts of nicotine – although the more nicotine there is, the bigger the reaction will be – so even darker vape juice.

So how do you stop your vape juice from turning dark while it’s in the bottle?

You can’t prevent your vape juice from turning slightly darker, but there are ways you can minimise how dark it turns. You can start by storing your vape juice in a cool, dark space, such as a kitchen cupboard or a desk drawer. Exposure to both light and heat will gradually darken the nicotine in your e-liquid and it’ll change colour. Storing it in a cool and dark place wont halt the oxidation process all together, but it will slow it down dramatically. Many e-liquid manufacturers actually store their juice in a fridge to slow down the process even further!

Minimising agitation is also key. When you shake your vape juice, sure you’re mixing the nicotine and the juice together as well as combining the flavours together but you’re also increasing how much oxygen is in the mix. When you shake the bottle you’ll notice tiny bubbles in the juice that will then float to the surface. There’s also tiny bubbles in there that are adding more oxygen to the mix, which will lead to darker juices forming quicker.

Another tip is to not top up your juices. So you’re left with a tank or two worth of juice in the bottom of a bottle and you’ve bought another just that you’ve started using, do you pour the leftovers into your new bottle? Absolutely not if you want cleaner looking juice for longer. When you do this, you’re adding already oxidised nicotine to the mix which will then contaminate the new bottle too.

So what about in your tank?

Most tanks have nothing but glass in between your juice and the sunlight – this isn’t great for the colour of your juice. That’s not all though, it has to do with the flavours in your vape juice. A lot of juices on the market contain artificial sweeteners and sugars to enhance the flavour.

As you fire your vape and the coil heats up, it starts to caramelize the sugars in the same way hard sweets are made. The caramelized juice is dark and turns to a gunk which sticks to your coil and to the cotton.

When enough of this gunk is formed, it starts to bleed out into the juice and stains it a brown colour and over time as it burns more and more, it can even turn your juice black.

How do you prevent dark tank juice?

Once you put the juice in your tank you can expect the oxidation to happen many times faster than it will in the bottle, this is because the bottle is sealed whereas your tank, by design, is very open to air. That said, there are ways to minimise how fast this happens, and the first is to try and avoid all of the sweeteners, which is easier said than done.

Companies typically don’t list their flavouring ingredients as a way to keep all their testing and research safe from copycats. As a rule of thumb, any “candy” ranges are highly likely to be full of sweeteners, which are tasty but bad for coils, so avoid those in general if you want to keep your coils for longer.

Unfortunately they aren’t alone though – any fruits, desserts, menthols or tobacco flavours can also have added sweeteners… this basically is every vape juice.

Once you’ve been vaping a while you’ll be able to tell which juices have lots of sweeteners and which don’t, unfortunately this is down to experience and isn’t something you can learn overnight. There is something you can take from this though.

Over time, as you simply swap out old coils and pop a new one in, gunk will build up inside your tank, coating the metal. When you add your juice to this it’ll begin oxidising.

The trick is – regular cleaning.

When you opt for a coil change, take out the old coil and get some kitchen roll in there, give it a good clean out, including in the drip tip where juice passes through regularly. By cleaning the tank with each coil change you’re going to get optimal performance and flavour out of each full tank!

Cleaning your tank involves taking the whole thing apart and wiping (or sometimes scrubbing!) it clean. Your coils will be better off, your juice will be better off, and as a result, your bank account will be better off.

While you’re on our blog, you might find these articles helpful!
Nicotine Numbers and Which Strength You Need
How to clean your vape tank
How coils work and when to change them
How to make juice last longer
How to make Coils last longer
Why vape juice turns dark
MTL and DTL – What’s the difference?
Nic Salts vs Freebase: The difference and benefits
What happens when you quit smoking
Vaping: Twice as effective as patches and gum?
Using E-cigs to stop smoking
How to choose your first vape/e-cig
The Problem with Home Crew Vape Shops

Or you may like our new kit breakdown series “OUTTHEBOX” where we give in depth explanations of vape kits and an unboxing experience.

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