How To Do Low Lying Fog (Ground Fog)

Updated on October 3, 2016

Ground fog can be easily achieved by understanding how fog works with its environment. This article will explain how to achieve this effect, along with providing suggestions to further increase the quality of the ground fog.

I will not be going into too much detail about the different types of fog machines or fluids because that is a lot of content.

This article is based on my experiences and the opinions expressed are my own! These techniques work for me and I hope they work for you!

Materials I'm Using

The fog machine I'm using is a 400 Watt ground fogger which I bought at Party City. Its called a ground fogger because, unlike normal fog machines, it has an ice compartment, which I will talk more about later. I am also using a high-density fog juice. This fog machine isn't the exact product that I'm using in the example videos and pictures I'm providing, but similarly to mine, it is a 400 Watt fog machine, has an identical structure, and should produce the same results.

It should also be noted that you do not need a "ground fogger." Any type of fog machine will work.

I usually use this High-Density Bog Fog juice, but I needed some fog juice for a party and didn't have time to wait for delivery. So, I bought the one displayed in my pictures at a local store here in Seattle called Party @ Display in Costume. It works pretty well, but it isn't as thick and doesn't last as long as the Bog Fog juice. You don't need to use high-density fog juice, but for ground fog, I recommend it.

Structure of a Fog Machine with an Ice Compartment

If you are curious, here is the structure of a fog machine with an ice compartment. You may not be able to see, but there is a partition separating the area before the ice compartment and the exiting chamber, so the fog must travel through the ice compartment before leaving the machine.

Controlling the Height of the Fog

The two main factors that affect how low or high your fog will be are the temperature of the fog and the temperature of the surrounding area. Basically, think of it like this:

  • The cooler your fog is, the lower it will stay.
  • The cooler you surroundings are, the higher your fog will rise.

Why? There are scientific reasons involving the density of air, but for simplicity, hot air rises and cool air sinks. So, if the fog is significantly cooler than its surroundings, it will stay lower for longer.

Creating Low Lying Fog

Low lying fog is something many people try to achieve. The best way to do this is to cool the fog down by having it travel through ice. Some fog machines, such as mine, have a small ice compartment. Also, having denser fog juice is important for low lying fog.

To the right, I have included two videos demonstrating my fog machine with and without ice. Notice how heavy the cold fog is compared to the light un-iced fog. The colder fog stays low and spreads across the floor. The fog without ice goes straight up and then begins to spread.

As time goes on, the colder fog will rise about 4-5 feet and dissipate, while the hotter fog will try to fill the room and linger a lot longer than the colder fog.

Making a Fog Chiller

If you are using a fog machine that doesn't have a cooling compartment, or you want to cool your fog even more, you can create a fog chiller. There are many simple ways to create a "fog chiller" for your fog machine. Here is a video by heylawnguy and he demonstrates how simple it is to make a fog chiller. In his chiller (and in most chillers) notice that there are three things to consider:

  1. How the fog machine will connect to the chiller.
  2. The structure of the chilling area.
  3. Where the fog will exit.

As heylawnguy has demonstrated, connecting your fog machine to the chiller can be as simple as cutting a hole in the container and placing your fog machine up to it. Or you can use other materials to create a better seal/connection between the fog machine and chiller.

When designing the chilling area, keep in mind that you want to chill your fog as much as you can. You can keep it simple, like heylawnguy did, but if you have some extra supplies, I advise adding some obstructions for the fog, so the fog will have to travel around, instead of being able to go straight through the fog chiller. Basically, you want to make it stay in the chiller longer, which will result in colder, lower fog.

Again, in heylawnguy's video, you can see that the exit hole in his chiller is wide. The size is good for a 400 Watt fog machine. If your fog machine has a higher wattage, you may want a bigger exit hole. This will help spread the fog and keep it low. If the exit isn't big enough, the fog will be forced out and will rise a few feet. I have seen people compensate by cutting a hole in a plastic bag or a box to fit the exit hole of the chiller and attaching it to the chiller, allowing the fog to spread out evenly when it exits the box or bag.

To the right is a video by MAKE. It demonstrates a pretty inexpensive fog chiller setup with the three pieces as described above:

  • A sealed connection from the fog machine to the entrance of the chiller.
  • A chiller the fog must travel around.
  • And a wide exit.

This is a good model to follow if you decide to make your own chiller for your machine. I like this design because both the chiller and the tube that the fog travels through are sealed. So, even when the ice melts, the water will stay in the chiller creating iced water.

Other Suggestions

Using Dry Ice to Cool your Fog

If you can afford it, I recommend using dry ice because it's extremely colder than regular ice made from water and, more importantly, there's no cleaning after it melts. Dry ice undergoes sublimation, which means it melts into a gas, not a liquid. Also, instead of using dry ice exclusively, you can add it to regular ice to slow down the melting rate of both ices.

The disadvantages to using dry ice, besides being more expensive than regular ice, is that you have to use it the day you buy it because it will melt, unless you happen to have a cooler that is capable of achieving a temperature of -100°F. If you didn't know, the normal household kitchen refrigerator can barely go below 0°F. With that being said, another disadvantage is handling it. You need thick gloves or you can suffer from a dry ice "burn" because of how cold it is.

Warm Up the Surroundings

Another way to help keep the fog low, if you are inside a building or room where you can control the temperature, turning on the heater before using your fog machine will help keep the fog low. The greater the contrast between the temperature of the surroundings and the fog, the lower your fog will be.

Questions & Answers


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        Andry Rakotomalala 7 months ago

        Dude, this was perfect! Thanks so much for your wealth of knowledge and for sharing it!