Why Does The Candle Jar Turn Black? 5 Reasons

This is a guide covering why the candle jar turns black.

It was a long day at work. You’re finally home and you have cosied up on the sofa with the book you’ve been waiting for ages to read.

You’ve lit your favourite scented candle nearby. It’s not only adding to the ambiance of the lounge, but it’s also adding to the comfort and aesthetic of the area. You feel like you’re living out of a Pinterest board.

It’s safe to say that life’s good.

Or not? Because you notice your candle jar turning black and it ruins the perfect night in.

Many candle users are often victims of this. This leads us to the obvious questions- why and how does this happen? What are the ways it can be avoided?

Read on to find the answers to these questions!

Why Does the Candle Jar Turn Black?

One word: Oxidation.

What is Oxidation? It is a chemical reaction, involving oxygen as one of the reactants.


Oxidation is an expansive term and involves an array of reactions- ranging from extremely slow to rapid. Rusting and burning fire are both forms of oxidation. However, the former occurs over a long time period, whereas the latter occurs in a matter of seconds.

Burning your candle is an example of an oxidation reaction.

How Does Oxidation Turn the Candle Jar Black?

The oxidation reaction involves a form of fuel- candle wax in this case- and oxygen for the reaction to start. When a candle burns, the oxidation process results in the creation of carbon dioxide and water molecules.

Both these substances are colourless and hence, do not impact the candle jar at all.

However, sometimes, when candles burn, they create another product- unburned carbon atoms. These particles are not colourless.

In fact, they are black in colour and rise up from the flame. But, they don’t evaporate in the air like carbon dioxide and oxygen. Instead, they deposit on the candle jar! So, these carbon atoms are the culprits, which turn the candle jar black!

What is the Black Stuff on Candles?


Drawing from the information mentioned in the last part, soot simply consists of unburned carbon atoms.

They are a byproduct of oxidation that settles on the walls of the candle jar, giving them a black colour.

Why Do Candles Leave Soot?

You don’t see soot deposits on every candle jar. Why is that the case?

Because burning candles does not always release unburned carbon atoms. That is only the result of an imperfect chemical reaction.

All the carbon present in the candle wax does not react with the oxygen available. As a result, the unburned carbon atoms or soot deposit on the candle jar, turning it black.

So, what contributes to the production of soot?

1. Too Many Additives in the Candle Wax

While a good scent is often the main reason why people want to buy candles, the good scent sometimes comes at a price. Too many additives are added to create this remarkable fragrance.

This disrupts the chemical composition of the pure wax and reduces the efficiency of burning. As a result, when it burns, too many unburned carbon atoms are released, destroying your pristine candle jar.

One easy way to avoid this problem is to buy your candle from a well-known manufacturer or shop.

Because any good quality candle will not add too many additives or too much of one additive.

2. Wick Length and Size

A wick that is too short or long will result in excess soot being deposited on your candle jar.

Moreover, if the wick is not cut to the ‘right’ length it will also cause your candle to burn too fast or too slow, leading to inefficient burning. This, again, will cause soot to deposit on your candle jar.

One essential thing to keep in mind is that there is no correct universal length for a wick; a longer candle will need a longer wick and vice versa.

If you are planning on making new candles, there will be a lot of experimenting involved in finding a suitable wick size. If you’re a newbie, get ready for a lot of trial and error to find the correct wick size.

3. Wick Material

Your wick’s length is not the only thing you need to get correct in order to prevent your candle jars from turning black. Wick material is just as important.

Many candle users swear by the fact that cotton is the best material to make wicks. Mainly because it is the best suited to the job.

Zinc, for instance, is another common material used to make wicks. However, it does not do the job right.

While zinc wicks provide great stability, they don’t burn as clean as cotton wicks. In other words, zinc wicks are a hindrance to the efficient burning of candle wax.

This leads to incomplete combustion of the candle wax, resulting in the production of soot.

4. Drafts

Many find the flickering of a flame aesthetic and comforting at the same time. That is an important attraction in buying candles!

However, too much of this flickering can lead to your candle jars turning black. Yes, that’s unfortunately right.

Why is that the case? When a candle is placed in a draft and flickers too much, it uses more wax to burn.

As more candle wax is used, more unburned carbon atoms are released. This leads to the deposition of soot on candle jars.

5. Insufficient Airflow

We have already seen that excessive air movements or drafts can lead to the production of soot. This will also happen when there is insufficient airflow.

A lack of airflows leads to a mismatch between the fuel and oxygen ratio that is required in an oxidation reaction. Due to this imbalance, caused by a shortage of oxygen, soot is created.

Soot production due to insufficient airflow is a common problem. When your candle wax gets shorter, it is deeper in the jar.

Meaning, there will be relatively less oxygen. As a result, your jar will start turning black.

The only way to avoid this is to replace the jar when the candle gets shorter.

How to Clean the Soot off Candle Jars?

If you have made sure to avoid all the reasons that lead to soot production but your candle jars have still turned black, there is no reason to get worked up!

In most cases, you can remove the soot without much trouble.

The method listed below works for candles which can be removed from candle jars.

  • First things first, make sure the candle is not burning. The wax must also be cooled down and the wick should not be hot either. Note: Don’t even try to remove the candle wax from the candle jar while they are hot.
  • Once the candle wax and candle jar have cooled down completely, remove the candle from the jar.
  • Find a paper towel or soft cloth and dampen it with water. Wipe the inside of the candle jar with this cloth. Since, the candle is removed from the jar, you will be able to clean the candle jar fully.
  • Soak the candle jar in warm, soapy water. After 20 minutes, use the soft cloth to give it one last clean before washing it with water and drying it.
  • Get another soft cloth and dampen it with rubbing alcohol. Rub the cloth against the candles until all the soot is removed.
  • Wait for the candles and candle jar to dry completely before lighting the candle!

If you can’t remove the candles from the candle jar, do not soak the candle jar in soapy water.

Clean the jar with a warm wet cloth which was soaked in soapy water. To clean the candle wax, only rub the top of the candle, which is exposed, with rubbing alcohol.

Does the Type of Candle Wax Affect This?


Some candle waxes tend to produce more soot than others. Hence, if you burn a candle wax that has a tendency to produce less soot, your candle jars are less likely to turn black.

This distinction is evident between paraffin and soy candles. Soy candles produce significantly less soot than paraffin candles.

Due to this characteristic of soy candles, they are commonly referred to as ‘clean burning candles’.

The reason behind this is that paraffin wax is derived from petroleum, while soy wax is derived from soybeans. The carbon content of petroleum is extremely high, which causes paraffin wax to produce excessive soot.

So, next time you buy a candle, make sure it’s a soy candle. It will be worth the investment and the candle aesthetic won’t be compromised!

How Do You Keep a Candle Jar From Turning Black?

  • Buy candles which are made from soy wax. These don’t emit any petro-carbon soot, which significantly reduces the chances of your candle jar turning black.
  • When you’re buying a candle also make sure that the wick is made of cotton.
  • Over the passage of time, make sure to continue cutting the wick of your candle to the size it was when you bought the candle.
  • When you’re burning the candle, make sure there’s not too much or too less of an airflow.
  • Buy your candle from a reputable company!

Follow these guidelines and you will have nothing to worry about!

Final Remarks

We hope this article answers all your concerns about your candle jars turning black! Remember, it doesn’t take much to ensure that your candle does not emit soot.

Avoid all the don’ts, which cause the candle to emit soot, and you’ll never have to stress a day about your candle jar turning black- ever!!