Why does my e-liquid change colour?

These are questions that we are often asked: why do e-liquids change colour? My e-liquid turns brown, is this normal? What causes this phenomenon and is it dangerous? Through this article, we list the origins of these discolourations, whether your e-liquid becomes brown or yellow.

Why does my e-liquid turn brown?

E-liquids that tend to turn brown may confuse you: how come my liquid changes colour once in the tank? Or when it is still in its bottle? Rest assured, nothing is alarming. The colour change of a juice has no toxicity. Here are the 4 cases where your e-liquid changes colour: 

• nicotine discolouration;
• certain aromas that discolour your e-liquid;
• discolouration due to the PG/VG base;
• the sun and heat as disturbing elements.

Discolouration due to nicotine

The nicotine present in e-liquids will change the colour of your liquid. This is a natural chemical reaction: the higher the nicotine level, the more the colour of your liquid will approach brown. So a light-coloured e-liquid will change colour as the maturation (homogenization of the different ingredients) takes place.

Flavours can discolour your e-liquid

Some flavours, such as vanillin or classics, also tend to brown e-liquids. Logically, a vanillin aroma coupled with a high nicotine level accentuates this phenomenon. So if you’re a DIYist and you’ve just made your mix, don’t panic! This colour change is completely normal.

Discolouration due to PG VG

The heating of your e-liquid by your resistance can also tend to brown your liquid. Propylene Glycol and vegetable glycerin, which make up the majority of your e-liquid, are two elements subject to a chemical reaction when the liquid is heated. This phenomenon generates residues which are stored in the bottom of your tank and discolours your e-liquids during your future fillings. To avoid this phenomenon, we simply recommend regular maintenance of your atomizer, and more particularly of your tank.

The sun or heat is the origin of this phenomenon

UV rays and heat can affect your e-liquid. UV discolours the aromas and nicotine present in your liquid: we then speak of oxidation of your e-liquid.

Regarding heat, we recommend keeping your e-liquids away from light or a source of excessive heat. It’s the same principle as in baking: a high temperature will cause the sugars to caramelize, making your e-liquid brown or yellowish.

Ideally, we recommend that you keep your e-liquid bottles away from light and at a temperature not exceeding 18-20°.

In conclusion, a liquid that turns brown or yellow is not toxic. This phenomenon of colour change can be due to aromas, nicotine, heating of the PG-VG during puffs, exposure to the sun or even heat.