How Do Candles Work?

Candles are quite amazing. We buy them, we use them, but we never give much thought to how they work. I have come across a lot of this information in my time using and researching candles and I think you will find it interesting. Let’s take a look at how candles work.

How do candles work? When you light a candle, the flame heats the wax and melts it. As it melts, the wick draws it up and as the wax approaches the flame it turns into vapor. This wax vapor breaks down into hydrogen and carbon, which reacts with oxygen to generate the flame we see.

All waxes are essentially hydrocarbons. Near the flame, this breaks down into hydrogen and carbon. The hydrogen and carbon interact with oxygen in the air and feeds the candle’s flame. A candle’s flame is essentially sustained by the combustion of gas made from wax.

The Study Of Candles

The operation of candles has always fascinated people. Universities and scientists have been researching them and studying them for hundreds of years. To this day students around the world learn about candles and the reactions that take place as a candle burns. As recent as the 1990’s NASA did experiments in space with candles to learn how microgravity impacts them.

nasa candle experiemnt - how do candles work
NASA Photo of gravity on a candle

On Earth, the heat from the flame makes the air around it expand. When the air near the flame expands it becomes lighter than the air around it. This means the hot air near the candle is constantly rising while the surrounding air remains the same. This is why a candle flame points up.

However, in space the difference in gravity between hot air and cold air is minimal. The heat does not rise and it can not give the candle flame its “normal” shape. This gives you the rounded flame that you see in the above picture. You can find out more about this NASA experiment on their website here.

What Are The Parts Of A Candle?

The parts of a container candle include the wick, wax, container, dye, and scent or perfume. The parts of a pillar candle include wick, wax, dye, and scent or perfume. These parts can vary depending on the candle type.

The parts can also be different depending on other factors such as gel candles, multi wick candles and more decorative containers.

Candle Wick

Candles can have several different types of wicks that each is designed for a different purpose. Some of the types of wicks are cored flat braided, square, lx, htp, and others.

I like to describe the wick as the “pilot light” of the candle. If you are familiar with a gas stove then you know the pilot light always burns and then when the gas kicks on it ignites it.

This is essentially the function a wick serves in a candle.


A variety of waxes are available. Paraffin wax, beeswax, soy wax, palm oil wax and coconut wax just to name a few. I suggest you avoid paraffin wax if possible. It is a petroleum byproduct that can release toxins.

Wax is the fuel of a candle. As mentioned above, when wax travels up the wick toward the flame it gets superheated and turns in to a gas (wax vapor) and that gas is what actually sustains the flame.


The container is what holds it all together. These usually come in a variety of jars and tins. Containers are not necessary for beeswax candles and some paraffin wax candles. They are solid enough to stand on their own even under elevated temperatures.

Candles such as soy wax and palm oil wax are made from hydrogenated oil and have a low melting point. This low melting point makes a container a must to hold all the molten wax.


This is what gives the candle it’s color. I feel like coloring is not necessary but some people like it. It does not add any benefit other than the aesthetic of seeing a different color wax.

Again, this is not a particularly important part of the candle one way or another unless your candle has something that releases toxins as it burns. Then it is an area of concern.


This is what gives the candle its smell and this is usually our favorite part. The fragrances used in candles can come from natural sources such as essential oils but they are often also man-made fragrances.

However, this is another example of something that can potentially release toxins. Depending on where the scent came from and if it is natural or not.

Common Candle Questions

Let’s take a look at some related candle questions.

Why Doesn’t A Candle Wick Burn Up?

Candle wicks do burn very slowly because of the wax. Not only is the wax the fuel of the candle, but it also regulates the burn. The liquid wax that travels up the wick also works to slow the burning of the candle. The liquid wax is not flammable, only the hot wax vapors.

Why Does The Wax Disappear When Burned?

The wax is being burned, that is why you see the amount of wax in a candle slowly disappearing. The wax heats and turns to gas and becomes hydrogen and carbon that reacts with oxygen and produces light, heat, water vapor, and carbon.

Can Candle Wax Catch On Fire?

Candle wax can catch on fire at a certain temperature. The flashpoint of candle wax is  395°F. This is why the double boiler method is suggested when you are melting wax to make candles. Follow a reputable candle making guide to avoid a wax disaster in your home.

How Do I Know When My Candle Is Done?

A candle is done when it only has 1/2 inch of wax left in the bottom of the container. You never want to burn a candle all the way to the bottom as the heat may crack or bust the container. When you get to the 1/2 inch point just scrape out the remaining wax and wash the container in hot water and dish liquid and you can repurpose it or recycle it.

Do you Breathe In Candle Wax?

It is unlikely that you are breathing in candle wax. In a properly burning candle, the combustion process is extremely efficient. In this state, the candle only releases heat, light, carbon dioxide, and water.

However, when you blow out a candle the smoke that goes into the air is not smoke, it is actually unburned candle wax vapor. This vapor is emitted from the hot wick after the flame is extinguished. So if you breathe this, you are breathing candle wax.

What Happens If you Inhale Candle Wax?

Inhaling candle particulates such as soot, smoke, and wax vapor can irritate your lungs. It can trigger an asthma attack and make breathing more difficult in those that have respiratory disorders. In addition, paraffin wax can contain toxins and carcinogens.

Which Candles Are Not Toxic?

Non-toxic candles include soy wax, beeswax, palm oil wax, coconut oil wax, and rapeseed wax. These types of wax are all carbon neutral and come from natural sources. They do not release any toxins or carcinogens. However, paraffin wax is a petroleum byproduct that can release both toxins and carcinogens.

Is Candle Wax Biodegradable?

Candle wax is biodegradable. This includes beeswax, soy wax, palm oil wax, rapeseed, and a variety of other vegetable-based waxes. Paraffin wax, however, is not as eco-friendly and biodegradable. In addition, paraffin wax is a petroleum byproduct that can have both toxins and carcinogens.

How Many Candles Are Sold Each Year?

Over 1 billion pounds of wax are used each year to produce candles in the United States. That is enough wax for 2,500,000,000 candles that are 8oz each. In addition, over 10,000 varieties of scented candles are sold.


In conclusion, candles are essentially the world’s first and one of its most efficient combustion machines.

A properly burning candle poses little threat to your health or breathing. It only releases carbon dioxide, water, light, and heat.

Keep your home and your family safe from possible toxins by burning only candles with natural origins and avoiding paraffin wax candles.

If you want to see more about how candles work then check out my article about how scented candles work here.

How Do Candles Work?

Carl Adamson

Hi, I'm Carl Adamson, one of the founders here at Candleers. A few years ago I got really into the art and craft of candle making, initially with soy wax container candles. My friends started asking me to make candles for them and pretty soon it turned into a nice side-business. I started this website as a way to document what I've learned over the past few years and hopefully help others in the process. I still love candle making but I'm learning that what I enjoy even more is the business side of things - and for this reason I've started consulting others on how to start and grow their own candle-making businesses and side-hustles.

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