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  • Writer's pictureZac Gnadinger

Why Vape Juice Turns Dark or Brown

Updated: Jun 11, 2020

You just bought a new bottle of vape juice that you’re super excited to try out.

The first few days the new juice tastes amazing, but shortly after you notice your golden liquid has since turned to a dark brown or black sitting in your tank.

Or even worse, you left that bottle of juice out for a couple weeks, just to come back to the whole bottle having turned brown.

There’s a simple explanation to why this happens, and today I’m going over just that.

Read on to find out why color change happens in both your vape tank and inside the bottle, and how to prevent it from happening again.

1.) Why Vape Juice Turns Brown in the Bottle

darkened vape juice difference in two e-liquid bottles

The reason why e-liquid starts to darken inside the bottle is due to a chemical reaction known as oxidation.

Nicotine is a highly reactive chemical and exposing it to oxygen, or even light, can cause it to react and turn vape juice into an all too familiar brown color.

The same thing even happens after slicing an apple;

If you leave those apple slices out for a while, their white flesh starts to brown a little.

Oxidation is a very normal process and should be expected from your e-juice, even if there are low amounts of nicotine.

Although, the more nicotine there is the more pronounced the reaction will be, meaning even darker vape juice.

How Do You Prevent Vape Juice from Darkening in the Bottle?

While you can’t prevent your e-juice from darkening entirely, there are things you can do to slow down the process:

  • Store Your E-liquid in a Cool, Dark Place.

Exposure to light and heat will gradually cause the nicotine in your e-liquid to change color.

Storing it in a cool, dark place won’t stop the darkening completely, but it helps slow down the oxidation process dramatically.

E-liquid manufacturers even store their nicotine mixtures inside of a refrigerator to prevent the reaction from happening for longer periods of time.

  • Avoid Agitating Your E-liquid as Much as You Can

Shaking your juice bottle may help mix the flavors together, but the agitation increases how much oxygen is being absorbed into the vape juice, making it darken faster.

By not agitating your e-juice, you can slow down the oxidation process even more.

  • Don’t Mix Different E-liquids

If you have an old and a new bottle of the same vape juice, keep them separate.

If you have to mix them, or are using different flavored or brands of e-juices, mix them in a separate, smaller bottle or container.

By doing this, you can avoid contaminating the entire fresh bottle with the already oxidized nicotine from the other juice.

2.) Why Vape Juice Turns Brown in Your Tank

oxidized juice difference in two vape tanks

Besides the fact that oxidation is sped up tenfold inside a vape tank, the biggest culprit of e-liquid turning dark in your tank are the ingredients.

Not all e-juices are created equal, and a lot of them on the market contain artificial sweeteners and sugars to add flavor.

As your coil heats up to vaporize the e-liquid, these sweeteners start to caramelize and stick to the coil and cotton.

Just like the process of making actual caramel, the results are very dark and gunky.

When enough builds up on the coil, this caramelized gunk begins to leach out into the juice and stain it a brown color.

And as the caramel burns more over time, your juice can even turn into a black color.

burnt coil from sweetener in vape tank

How Do You Prevent Vape Juice from Darkening in Your Tank?

While your juice may still darken slightly from the oxidation inside the tank, there are ways to minimize the darkening happening from added sweeteners:

  • Avoid Added Sweeteners as Best You Can

This is easier said than done since companies don’t list their flavoring ingredients, but as a general rule of thumb, any e-liquid brand that claims to be a candy flavored line are most likely loaded with sweeteners.

They’re not alone though!

Any fruit, dessert, menthol, or tobacco flavor can contain added sweeteners; basically everything.

This is where an experienced vape shop employee comes in handy.

After you’ve worked with flavors for long enough, you’re able to taste if a certain e-juice contains any added sweeteners, which is why the employee should be able to help steer you away from them.

Want a safe bet?

At La Dulce Vapor Lab, our house juice contains no added sweetener!

You can view our full line here.

  • Regularly Clean Your Vape Tank and Change Your Coil

Over time, gunk from past coils and e-liquid can leave behind a residue.

Without regular cleaning, this buildup will start to darken any new juice added to your tank, which can start to affect the flavor too.

By cleaning your vape tank with every coil change, you ensure that you’re getting the optimal performance and flavor out of your tank.

Click here to learn more about cleaning a vape tank.

disassembled vape tank and its parts

In Conclusion

There you have it; the main reasons why color change happens in both a vape tank and inside the bottle, and how to prevent it from happening.

If you have any further questions about what I’ve discussed here, feel free to leave a comment below!

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jacob mills
jacob mills
Nov 11, 2023

So does oxidation have any effect on flavor or nicotine potency? Or is it simply just a visual thing


Andrea Collier
Andrea Collier
May 11, 2023

Great info. My flatmate I believe has spilt some on a wood table as there is now a clear vape device shape dark stain. Any ideas how to remove that? It would have been spilt a few days ago and is now dried :(


Sandy Shean
Sandy Shean
Sep 15, 2022

If oxidation (a chemical reaction) occurs and your refill has changed color, has the nicotine been affected in any way?

Lane Kareem
Lane Kareem
Sep 15, 2022
Replying to

I haven't noticed any difference.


free weelers
free weelers
Apr 03, 2022

I have been purchasing VUSE Pods from 7 11 Stores around Austin TX and getting 2 clear pods along with 2 dark oxidized pods in my 4 pack. At first no problem but it's been every 4 pack I've purchased in town for past 3 months I'm about to quit buying VUSE products I'm so mad about this !!!!

Lane Kareem
Lane Kareem
Sep 15, 2022
Replying to

Do all four smoke/taste the same?


Lane Kareem
Lane Kareem
Aug 10, 2021

Thanks for the info!

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